The string returned from StackTrace documents the sequence of calls that resulted in the throwing of this exception. Notice how the bottommost line number of this string identifies the first call in the
\nsequence, while the topmost line number identifies the exact location of the offending member. Clearly, this information can be quite helpful during the debugging or logging of a given application, as you are able to \u201cfollow the flow\u201d of the error\u2019s origin.
\n\u4ece StackTrace \u8fd4\u56de\u7684\u5b57\u7b26\u4e32\u8bb0\u5f55\u4e86\u5bfc\u81f4\u5f15\u53d1\u6b64\u5f02\u5e38\u7684\u8c03\u7528\u5e8f\u5217\u3002\u8bf7\u6ce8\u610f\u6b64\u5b57\u7b26\u4e32\u6700\u5e95\u90e8\u7684\u884c\u53f7\u5982\u4f55\u6807\u8bc6\u5e8f\u5217\uff0c\u800c\u6700\u4e0a\u9762\u7684\u884c\u53f7\u6807\u8bc6\u8fdd\u89c4\u6210\u5458\u7684\u786e\u5207\u4f4d\u7f6e\u3002\u663e\u7136\uff0c\u5728\u8c03\u8bd5\u6216\u8bb0\u5f55\u7ed9\u5b9a\u5e94\u7528\u7a0b\u5e8f\u671f\u95f4\uff0c\u6b64\u4fe1\u606f\u975e\u5e38\u6709\u7528\uff0c\u56e0\u4e3a\u60a8\u53ef\u4ee5\u201c\u8ddf\u8e2a\u9519\u8bef\u6765\u6e90\u7684\u6d41\u7a0b\u201d\u3002<\/p>\n
The HelpLink Property<\/h2>\n
\u5e2e\u52a9\u94fe\u63a5\u5c5e\u6027<\/p>\n
While the TargetSite and StackTrace properties allow programmers to gain an understanding of a given exception, this information is of little use to the end user. As you have already seen, the System.Exception. Message property can be used to obtain human-readable information that can be displayed to the current user. In addition, the HelpLink property can be set to point the user to a specific URL or standard help file that contains more detailed information.
\n\u867d\u7136 TargetSite \u548c StackTrace \u5c5e\u6027\u5141\u8bb8\u7a0b\u5e8f\u5458\u4e86\u89e3\u7ed9\u5b9a\u7684\u5f02\u5e38\uff0c\u4f46\u6b64\u4fe1\u606f\u5bf9\u6700\u7ec8\u7528\u6237\u51e0\u4e4e\u6ca1\u6709\u7528\u5904\u3002\u6b63\u5982\u60a8\u5df2\u7ecf\u770b\u5230\u7684\uff0cSystem.Exception\u3002\u6d88\u606f\u5c5e\u6027\u53ef\u7528\u4e8e\u83b7\u53d6\u53ef\u663e\u793a\u7ed9\u5f53\u524d\u7528\u6237\u7684\u4eba\u7c7b\u53ef\u8bfb\u4fe1\u606f\u3002\u6b64\u5916\uff0c\u8fd8\u53ef\u4ee5\u5c06 HelpLink \u5c5e\u6027\u8bbe\u7f6e\u4e3a\u5c06\u7528\u6237\u6307\u5411\u5305\u542b\u66f4\u591a\u8be6\u7ec6\u4fe1\u606f\u7684\u7279\u5b9a URL \u6216\u6807\u51c6\u5e2e\u52a9\u6587\u4ef6\u3002<\/p>\n
By default, the value managed by the HelpLink property is an empty string. Update the exception using object initialization to provide a more interesting value. Here are the relevant updates to the Car. Accelerate() method:
\n\u9ed8\u8ba4\u60c5\u51b5\u4e0b\uff0c\u7531\u5e2e\u52a9\u94fe\u63a5\u5c5e\u6027\u7ba1\u7406\u7684\u503c\u4e3a\u7a7a\u5b57\u7b26\u4e32\u3002\u4f7f\u7528\u5bf9\u8c61\u521d\u59cb\u5316\u66f4\u65b0\u5f02\u5e38\u4ee5\u63d0\u4f9b\u66f4\u6709\u8da3\u7684\u503c\u3002\u4ee5\u4e0b\u662f\u6c7d\u8f66\u7684\u76f8\u5173\u66f4\u65b0\u3002\u52a0\u901f\uff08\uff09 \u65b9\u6cd5\uff1a<\/p>\n
public void Accelerate(int delta)
\n{
\nif (_carIsDead)
\n{
\nConsole.WriteLine("{0} is out of order...", PetName);
\n}
\nelse
\n{
\nCurrentSpeed += delta;
\nif (CurrentSpeed >= MaxSpeed)
\n{
\nCurrentSpeed = 0;
\n_carIsDead = true;<\/p>\n
\/\/ Use the "throw" keyword to raise an exception and The catch logic could now be updated to print this help-link information as follows:<\/p>\n catch(Exception e) \u6570\u636e\u5c5e\u6027<\/p>\n The Data property of System.Exception allows you to fill an exception object with relevant auxiliary information (such as a timestamp). The Data property returns an object implementing an interface named IDictionary, defined in the System.Collections namespace. Chapter 8 examines the role of interface- based programming, as well as the System.Collections namespace. For the time being, just understand that dictionary collections allow you to create a set of values that are retrieved using a specific key. Observe the next update to the Car.Accelerate() method: public void Accelerate(int delta) }; To successfully enumerate over the key-value pairs, make sure you added a using directive for the System.Collections namespace since you will use a DictionaryEntry type in the file containing the class implementing your top-level statements. using System.Collections;<\/p>\n Next, you need to update the catch logic to test that the value returned from the Data property is not null (the default value). After that, you use the Key and Value properties of the DictionaryEntry type to print the custom data to the console. catch (Exception e) With this, here\u2019s the final output you\u2019d see: Simple Exception Example <\/em><\/strong><\/strong> -> Custom Data: Out of exception logic <\/em><\/strong><\/strong><\/p>\n The Data property is useful in that it allows you to pack in custom information regarding the error at hand, without requiring the building of a new class type to extend the Exception base class. As helpful as the Data property may be, however, it is still common for developers to build strongly typed exception classes, which handle custom data using strongly typed properties. This approach allows the caller to catch a specific exception-derived type, rather than having to dig into a data collection to obtain additional details. To understand how to do this, you need to examine the distinction between system-level and application-level exceptions. \u7cfb\u7edf\u7ea7\u5f02\u5e38\uff08System.SystemException\uff09<\/p>\n The .NET base class libraries define many classes that ultimately derive from System.Exception. For example, the System namespace defines core exception objects such as ArgumentOutOfRangeException, IndexOutOfRangeException, StackOverflowException, and so forth. Other namespaces define exceptions that reflect the behavior of that namespace. For example, System.Drawing.Printing defines printing exceptions, System.IO defines input\/output-based exceptions, System.Data defines database-centric exceptions, and so forth. Exceptions that are thrown by the .NET platform are (appropriately) called system exceptions. These exceptions are generally regarded as nonrecoverable, fatal errors. System exceptions derive directly from a base class named System.SystemException, which in turn derives from System.Exception (which derives from System.Object). public class SystemException : Exception Given that the System.SystemException type does not add any functionality beyond a set of custom constructors, you might wonder why SystemException exists in the first place. Simply put, when an exception type derives from System.SystemException, you are able to determine that the .NET runtime is the entity that has thrown the exception, rather than the code base of the executing application. You can verify this quite simply using the is keyword. \/\/ True! NullReferenceException is-a SystemException. NullReferenceException nullRefEx = new NullReferenceException(); Console.WriteLine( \u5e94\u7528\u7a0b\u5e8f\u7ea7\u5f02\u5e38\uff08System.ApplicationException\uff09<\/p>\n Given that all .NET exceptions are class types, you are free to create your own application-specific exceptions. However, because the System.SystemException base class represents exceptions thrown from the runtime, you might naturally assume that you should derive your custom exceptions from the System.Exception type. You could do this, but you could instead derive from the System. ApplicationException class. public class ApplicationException : Exception Like SystemException, ApplicationException does not define any additional members beyond a set of constructors. Functionally, the only purpose of System.ApplicationException is to identify the source of the error. When you handle an exception deriving from System.ApplicationException, you can assume the exception was raised by the code base of the executing application, rather than by the .NET Core base class libraries or .NET runtime engine. \u6784\u5efa\u81ea\u5b9a\u4e49\u5f02\u5e38\uff0c\u91c7\u7528 1<\/p>\n While you can always throw instances of System.Exception to signal a runtime error (as shown in the first example), it is sometimes advantageous to build a strongly typed exception that represents the unique details of your current problem. For example, assume you want to build a custom exception (named CarIsDeadException) to represent the error of speeding up a doomed automobile. The first step is to derive a new class from System.Exception\/System.ApplicationException (by convention, all exception class names end with the Exception suffix). \u25a0 Note as a rule, all custom exception classes should be defined as public classes (recall that the default access modifier of a non-nested type is internal). The reason is that exceptions are often passed outside of assembly boundaries and should therefore be accessible to the calling code base. Create a new Console Application project named CustomException, copy the previous Car.cs and Radio.cs files into your new project, and change the namespace that defines the Car and Radio types from SimpleException to CustomException. Next, add a new file named CarIsDeadException.cs and add the following class definition: namespace CustomException; As with any class, you are free to include any number of custom members that can be called within the catch block of the calling logic. You are also free to override any virtual members defined by your parent classes. For example, you could implement CarIsDeadException by overriding the virtual Message property. As well, rather than populating a data dictionary (via the Data property) when throwing the exception, the constructor allows the sender to pass in a timestamp and reason for the error. Finally, the timestamp data and cause of the error can be obtained using strongly typed properties. public class CarIsDeadException : ApplicationException public CarIsDeadException(){} \/\/ Override the Exception.Message property. public override string Message Here, the CarIsDeadException class maintains a private field (_messageDetails) that represents data regarding the current exception, which can be set using a custom constructor. Throwing this exception from the Accelerate() method is straightforward. Simply allocate, configure, and throw a CarIsDeadException type rather than a System.Exception. \/\/ Throw the custom CarIsDeadException. public void Accelerate(int delta) To catch this incoming exception, your catch scope can now be updated to catch a specific CarIsDeadException type (however, given that CarIsDeadException \u201cis-a\u201d System.Exception, it is still permissible to catch a System.Exception as well). using CustomException;<\/p>\n Console.WriteLine(" Fun with Custom Exceptions <\/em><\/strong><\/strong>\\n"); Car myCar = new Car("Rusty", 90);<\/p>\n try { So, now that you understand the basic process of building a custom exception, it\u2019s time to build on that knowledge. \u6784\u5efa\u81ea\u5b9a\u4e49\u5f02\u5e38\uff0c\u91c7\u7528 2<\/p>\n The current CarIsDeadException type has overridden the virtual System.Exception.Message property to configure a custom error message and has supplied two custom properties to account for additional bits of data. In reality, however, you are not required to override the virtual Message property, as you could simply pass the incoming message to the parent\u2019s constructor as follows: public class CarIsDeadException : ApplicationException public CarIsDeadException() { }<\/p>\n \/\/ Feed message to parent constructor. Notice that this time you have not defined a string variable to represent the message and have not overridden the Message property. Rather, you are simply passing the parameter to your base class constructor. With this design, a custom exception class is little more than a uniquely named class deriving from System. ApplicationException (with additional properties if appropriate), devoid of any base class overrides. Don\u2019t be surprised if most (if not all) of your custom exception classes follow this simple pattern. Many times, the role of a custom exception is not necessarily to provide additional functionality beyond what is inherited from the base classes but to supply a strongly named type that clearly identifies the nature of the error so the client can provide different handler logic for different types of exceptions. \u6784\u5efa\u81ea\u5b9a\u4e49\u5f02\u5e38\uff0c\u91c7\u7528 3<\/p>\n If you want to build a truly prim-and-proper custom exception class, you want to make sure your custom exception does the following: To complete your examination of building custom exceptions, here is the final iteration of CarIsDeadException, which accounts for each of these special constructors (the properties would be as shown in the previous example): public class CarIsDeadException : ApplicationException public CarIsDeadException(){} public CarIsDeadException(string cause, DateTime time, string message, System. Exception inner) With this update to your custom exception, update the Accelerate() method to the following: throw new CarIsDeadException("You have a lead foot", DateTime.Now,$"{PetName} has overheated!") Given that building custom exceptions that adhere to .NET Core best practices really differ by only their name, you will be happy to know that Visual Studio provides a code snippet template named Exception that will autogenerate a new exception class that adheres to .NET best practices. To activate it, type exc in the editor and hit the Tab key (in Visual Studio, hit the Tab key twice). \u5904\u7406\u591a\u4e2a\u5f02\u5e38<\/p>\n In its simplest form, a try block has a single catch block. In reality, though, you often run into situations where the statements within a try block could trigger numerous possible exceptions. Create a new Now, update Car\u2019s Accelerate() method to also throw a predefined base class library ArgumentOutOfRangeException if you pass an invalid parameter (which you can assume is any value less than zero). Note the constructor of this exception class takes the name of the offending argument as the first string, followed by a message describing the error. \/\/ Test for invalid argument before proceeding. public void Accelerate(int delta) \u25a0 Note The nameof() operator returns a string representing the name of the object, in this example the variable delta. This is a safer way to refer to C# objects, methods, and variables when the string version is required. The catch logic could now specifically respond to each type of exception. using ProcessMultipleExceptions;<\/p>\n Console.WriteLine(" Handling Multiple Exceptions <\/em><\/strong><\/strong>\\n"); Car myCar = new Car("Rusty", 90); When you are authoring multiple catch blocks, you must be aware that when an exception is thrown, it will be processed by the first appropriate catch. To illustrate exactly what the \u201cfirst appropriate\u201d catch means, assume you retrofitted the previous logic with an additional catch scope that attempts to handle all exceptions beyond CarIsDeadException and ArgumentOutOfRangeException by catching a general System. Exception as follows: \/\/ This code will not compile! try This exception handling logic generates compile-time errors. The problem is that the first catch block can handle anything derived from System.Exception (given the \u201cis-a\u201d relationship), including the CarIsDeadException and ArgumentOutOfRangeException types. Therefore, the final two catch blocks are unreachable! The rule of thumb to keep in mind is to make sure your catch blocks are structured such that the first catch is the most specific exception (i.e., the most derived type in an exception-type inheritance chain), leaving the final catch for the most general (i.e., the base class of a given exception inheritance chain, in this case System.Exception). Thus, if you want to define a catch block that will handle any errors beyond CarIsDeadException and \/\/ This code compiles just fine. \/\/ This will catch any other exception \u25a0 Note Where at all possible, always favor catching specific exception classes, rather than a general System.Exception. Though it might appear to make life simple in the short term (you may think \u201cah! This catches all the other things I don\u2019t care about.\u201d), in the long term you could end up with strange runtime crashes, as a more serious error was not directly dealt with in your code. remember, a final catch block that deals with System.Exception tends to be very general indeed. \u4e00\u822c\u6355\u83b7\u58f0\u660e<\/p>\n C# also supports a \u201cgeneral\u201d catch scope that does not explicitly receive the exception object thrown by a given member. \/\/ A generic catch. Obviously, this is not the most informative way to handle exceptions since you have no way to obtain meaningful data about the error that occurred (such as the method name, call stack, or custom message). Nevertheless, C# does allow for such a construct, which can be helpful when you want to handle all errors in a general fashion. \u91cd\u65b0\u5f15\u53d1\u5f02\u5e38<\/p>\n When you catch an exception, it is permissible for the logic in a try block to rethrow the exception up the call stack to the previous caller. To do so, simply use throw() within a catch block. This passes the exception up the chain of calling logic, which can be helpful if your catch block is only able to partially handle the error at hand. \/\/ Passing the buck. Be aware that, in this example code, the ultimate receiver of CarIsDeadException is the .NET runtime because it is the top-level statements rethrowing the exception. Because of this, your end user is presented with a system-supplied error dialog box. Typically, you would only rethrow a partial handled exception to a caller that has the ability to handle the incoming exception more gracefully. Notice as well that you are not explicitly rethrowing the CarIsDeadException object but rather making use of throw() with no argument. You\u2019re not creating a new exception object; you\u2019re just rethrowing \u5185\u90e8\u5f02\u5e38<\/p>\n As you might suspect, it is entirely possible to trigger an exception at the time you are handling another exception. For example, assume you are handling a CarIsDeadException within a particular catch scope and during the process you attempt to record the stack trace to a file on your C: drive named carErrors. txt (the implicit global using statements grant you access to the System.IO namespace and its I\/O- centric types). catch(CarIsDeadException e) Now, if the specified file is not located on your C: drive, the call to File.Open() results in a FileNotFoundException! Later in this book, you will learn all about the System.IO namespace where you\u2019ll discover how to programmatically determine whether a file exists on the hard drive before attempting to open the file in the first place (thereby avoiding the exception altogether). However, to stay focused on the topic of exceptions, assume the exception has been raised. When you encounter an exception while processing another exception, best practice states that you should record the new exception object as an \u201cinner exception\u201d within a new object of the same type as the initial exception. (That was a mouthful!) The reason you need to allocate a new object of the exception being handled is that the only way to document an inner exception is via a constructor parameter. Consider the following code: \/\/Update the exception handler catch (CarIsDeadException e) try Notice, in this case, I have passed in the FileNotFoundException object as the fourth parameter to the CarIsDeadException constructor. After you have configured this new object, you throw it up the call stack to the next caller, which in this case would be the top-level statements. Given that there is no \u201cnext caller\u201d after the top-level statements to catch the exception, you would be again presented with an error dialog box. Much like the act of rethrowing an exception, recording inner exceptions is usually useful only when the caller has the ability to gracefully catch the exception in the first place. If this is the case, the caller\u2019s catch logic can use the InnerException property to extract the details of the inner exception object. \u6700\u540e\u7684\u8857\u533a Console.WriteLine(" Handling Multiple Exceptions <\/em><\/strong><\/strong>\\n"); Car myCar = new Car("Rusty", 90); finally If you did not include a finally block, the radio would not be turned off if an exception were encountered (which might or might not be problematic). In a more real-world scenario, when you need to dispose of objects, close a file, or detach from a database (or whatever), a finally block ensures a location for proper cleanup. \u5f02\u5e38\u7b5b\u9009\u5668<\/p>\n C# 6 introduced a new clause that can be placed on a catch scope, via the when keyword. When you add this clause, you have the ability to ensure that the statements within a catch block are executed only if some condition in your code holds true. This expression must evaluate to a Boolean (true or false) and can be obtained by using a simple code statement in the when definition itself or by calling an additional method in your code. In a nutshell, this approach allows you to add \u201cfilters\u201d to your exception logic. Consider the following modified exception logic. I have added a when clause to the CarIsDeadException handler to ensure the catch block is never executed on a Friday (a contrived example, but who wants their automobile to break down right before the weekend?). Notice that the single Boolean statement in the when clause must be wrapped in parentheses. catch (CarIsDeadException e) when (e.ErrorTimeStamp.DayOfWeek != DayOfWeek.Friday) Console.WriteLine(e.Message); While this example is very contrived, a more realistic use for using an exception filter is to catch SystemExceptions. For example, suppose your code is saving data to the database, a general exception is thrown. By examining the message and exception data, you can create specific handlers based on what caused the exception. \/\/ Debugging Unhandled Exceptions Using Visual Studio Visual Studio supplies a number of tools that help you debug unhandled exceptions. Assume you have increased the speed of a Car object beyond the maximum but this time did not bother to wrap your call within a try block. If you start a debugging session within Visual Studio (using the Debug \u27a4 Start Debugging menu selection), Visual Studio automatically breaks at the time the uncaught exception is thrown. Better yet, you are presented with a window (see Figure 7-1) displaying the value of the Message property. Figure 7-1. Debugging unhandled custom exceptions with Visual Studio \u25a0 Note If you fail to handle an exception thrown by a method in the .neT base class libraries, the Visual studio debugger breaks at the statement that called the offending method. If you click the View Detail link, you will find the details regarding the state of the object (see Figure 7-2). Figure 7-2. Viewing exception details \u603b\u7ed3<\/p>\n In this chapter, you examined the role of structured exception handling. When a method needs to send an error object to the caller, it will allocate, configure, and throw a specific System.Exception-derived type via throw(). The caller is able to handle any possible incoming exceptions using the C# catch keyword and an optional finally scope. Since C# 6.0, the ability to create exception filters using the optional when keyword was added, and C# 7 has expanded the locations from where you can throw exceptions. When you are creating your own custom exceptions, you ultimately create a class type deriving from System.ApplicationException, which denotes an exception thrown from the currently executing CHAPTER 7 Understanding Structured Exception Handling \u7b2c7\u7ae0 \u4e86\u89e3\u7ed3\u6784\u5316\u5f02\u5e38\u5904\u7406 In this chapter, you will learn how to handle runtime anomalies in your C# code through the use of structured exception handling. Not only will you examine the C# keywords that allow you to handle such matters (try, catch, throw, finally, when), but you will also come […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[22],"class_list":["post-301","post","type-post","status-publish","format-standard","hentry","category-csharp","tag-pro-csharp10-with-net6"],"_links":{"self":[{"href":"https:\/\/diji.net\/index.php?rest_route=\/wp\/v2\/posts\/301","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/diji.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/diji.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/diji.net\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/diji.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=301"}],"version-history":[{"count":0,"href":"https:\/\/diji.net\/index.php?rest_route=\/wp\/v2\/posts\/301\/revisions"}],"wp:attachment":[{"href":"https:\/\/diji.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=301"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/diji.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=301"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/diji.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=301"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
\n\/\/ return to the caller.
\nthrow new Exception($"{PetName} has overheated!")
\n{
\nHelpLink = "http:\/\/www.CarsRUs.com<\/a><\/a><\/a>"
\n};
\n}
\nConsole.WriteLine("=> CurrentSpeed = {0}", CurrentSpeed);
\n}
\n}<\/p>\n
\n{
\n...
\nConsole.WriteLine("Help Link: {0}", e.HelpLink);
\n}<\/p>\nThe Data Property<\/h2>\n
\nSystem.Exception \u7684 Data \u5c5e\u6027\u5141\u8bb8\u60a8\u4f7f\u7528\u76f8\u5173\u7684\u8f85\u52a9\u4fe1\u606f\uff08\u5982\u65f6\u95f4\u6233\uff09\u586b\u5145\u5f02\u5e38\u5bf9\u8c61\u3002Data \u5c5e\u6027\u8fd4\u56de\u4e00\u4e2a\u5bf9\u8c61\uff0c\u8be5\u5bf9\u8c61\u5b9e\u73b0\u5728 System.Collections \u547d\u540d\u7a7a\u95f4\u4e2d\u5b9a\u4e49\u7684\u540d\u4e3a IDictionary \u7684\u63a5\u53e3\u3002\u7b2c8\u7ae0\u63a2\u8ba8\u4e86\u57fa\u4e8e\u63a5\u53e3\u7684\u7f16\u7a0b\u4ee5\u53caSystem.Collections\u547d\u540d\u7a7a\u95f4\u7684\u4f5c\u7528\u3002\u76ee\u524d\uff0c\u53ea\u9700\u4e86\u89e3\u5b57\u5178\u96c6\u5408\u5141\u8bb8\u60a8\u521b\u5efa\u4e00\u7ec4\u4f7f\u7528\u7279\u5b9a\u952e\u68c0\u7d22\u7684\u503c\u3002\u89c2\u5bdf Car.Accelerate\uff08\uff09 \u65b9\u6cd5\u7684\u4e0b\u4e00\u6b21\u66f4\u65b0\uff1a<\/p>\n
\n{
\nif (_carIsDead)
\n{
\nConsole.WriteLine("{0} is out of order...", PetName);
\n}
\nelse
\n{
\nCurrentSpeed += delta;
\nif (CurrentSpeed >= MaxSpeed)
\n{
\nConsole.WriteLine("{0} has overheated!", PetName); CurrentSpeed = 0;
\n_carIsDead = true;
\n\/\/ Use the "throw" keyword to raise an exception
\n\/\/ and return to the caller.
\nthrow new Exception($"{PetName} has overheated!")
\n{
\nHelpLink = "http:\/\/www.CarsRUs.com<\/a><\/a><\/a>", Data = {
\n{"TimeStamp",$"The car exploded at {DateTime.Now}"},
\n{"Cause","You have a lead foot."}
\n}<\/p>\n
\n}
\nConsole.WriteLine("=> CurrentSpeed = {0}", CurrentSpeed);
\n}
\n}<\/p>\n
\n\u82e5\u8981\u6210\u529f\u679a\u4e3e\u952e\u503c\u5bf9\uff0c\u8bf7\u786e\u4fdd\u4e3a System.Collections \u547d\u540d\u7a7a\u95f4\u6dfb\u52a0\u4e86 using \u6307\u4ee4\uff0c\u56e0\u4e3a\u60a8\u5c06\u5728\u5305\u542b\u5b9e\u73b0\u9876\u7ea7\u8bed\u53e5\u7684\u7c7b\u7684\u6587\u4ef6\u4e2d\u4f7f\u7528 DictionaryEntry \u7c7b\u578b\u3002<\/p>\n
\n\u63a5\u4e0b\u6765\uff0c\u9700\u8981\u66f4\u65b0 catch \u903b\u8f91\u4ee5\u6d4b\u8bd5\u4ece Data \u5c5e\u6027\u8fd4\u56de\u7684\u503c\u662f\u5426\u4e0d\u4e3a null\uff08\u9ed8\u8ba4\u503c\uff09\u3002\u4e4b\u540e\uff0c\u60a8\u53ef\u4ee5\u4f7f\u7528 DictionaryEntry \u7c7b\u578b\u7684\u952e\u548c\u503c\u5c5e\u6027\u5c06\u81ea\u5b9a\u4e49\u6570\u636e\u6253\u5370\u5230\u63a7\u5236\u53f0\u3002<\/p>\n
\n{
\n...
\nConsole.WriteLine("\\n-> Custom Data:"); foreach (DictionaryEntry de in e.Data)
\n{
\nConsole.WriteLine("-> {0}: {1}", de.Key, de.Value);
\n}
\n}<\/p>\n
\n\u6709\u4e86\u8fd9\u4e2a\uff0c\u8fd9\u662f\u60a8\u5c06\u770b\u5230\u7684\u6700\u7ec8\u8f93\u51fa\uff1a<\/p>\n
\n=> Creating a car and stepping on it! Jamming...
\n=> CurrentSpeed = 30
\n=> CurrentSpeed = 40
\n=> CurrentSpeed = 50
\n=> CurrentSpeed = 60
\n=> CurrentSpeed = 70
\n=> CurrentSpeed = 80
\n=> CurrentSpeed = 90
\n Error! <\/em><\/strong>
\nMember name: Void Accelerate(Int32)
\nClass defining member: SimpleException.Car Member type: Method
\nMessage: Zippy has overheated! Source: SimpleException
\nStack: at SimpleException.Car.Accelerate(Int32 delta) ... at SimpleException.Program.Main(String[] args) ...
\nHelp Link: http:\/\/www.CarsRUs.com<\/a><\/a><\/a><\/p>\n
\n-> TimeStamp: The car exploded at 3\/15\/2020 16:22:59
\n-> Cause: You have a lead foot.<\/p>\n
\nData \u5c5e\u6027\u975e\u5e38\u6709\u7528\uff0c\u56e0\u4e3a\u5b83\u5141\u8bb8\u60a8\u6253\u5305\u6709\u5173\u5f53\u524d\u9519\u8bef\u7684\u81ea\u5b9a\u4e49\u4fe1\u606f\uff0c\u800c\u65e0\u9700\u751f\u6210\u65b0\u7684\u7c7b\u7c7b\u578b\u6765\u6269\u5c55 Exception \u57fa\u7c7b\u3002\u4f46\u662f\uff0c\u5c3d\u7ba1 Data \u5c5e\u6027\u53ef\u80fd\u5f88\u6709\u5e2e\u52a9\uff0c\u4f46\u5f00\u53d1\u4eba\u5458\u4ecd\u7136\u5f88\u5e38\u89c1\u5730\u751f\u6210\u5f3a\u7c7b\u578b\u5f02\u5e38\u7c7b\uff0c\u8fd9\u4e9b\u5f02\u5e38\u7c7b\u4f7f\u7528\u5f3a\u7c7b\u578b\u5c5e\u6027\u5904\u7406\u81ea\u5b9a\u4e49\u6570\u636e\u3002<\/p>\n
\nData \u5c5e\u6027\u975e\u5e38\u6709\u7528\uff0c\u56e0\u4e3a\u5b83\u5141\u8bb8\u60a8\u6253\u5305\u6709\u5173\u5f53\u524d\u9519\u8bef\u7684\u81ea\u5b9a\u4e49\u4fe1\u606f\uff0c\u800c\u65e0\u9700\u751f\u6210\u65b0\u7684\u7c7b\u7c7b\u578b\u6765\u6269\u5c55 Exception \u57fa\u7c7b\u3002\u4f46\u662f\uff0c\u5c3d\u7ba1 Data \u5c5e\u6027\u53ef\u80fd\u5f88\u6709\u5e2e\u52a9\uff0c\u4f46\u5f00\u53d1\u4eba\u5458\u4ecd\u7136\u5f88\u5e38\u89c1\u5730\u751f\u6210\u5f3a\u7c7b\u578b\u5f02\u5e38\u7c7b\uff0c\u8fd9\u4e9b\u5f02\u5e38\u7c7b\u4f7f\u7528\u5f3a\u7c7b\u578b\u5c5e\u6027\u5904\u7406\u81ea\u5b9a\u4e49\u6570\u636e\u3002<\/p>\nSystem-Level Exceptions (System.SystemException)<\/h2>\n
\n.NET \u57fa\u7c7b\u5e93\u5b9a\u4e49\u4e86\u8bb8\u591a\u6700\u7ec8\u6d3e\u751f\u81ea System.Exception \u7684\u7c7b\u3002\u4f8b\u5982\uff0c\u547d\u540d\u7a7a\u95f4\u5b9a\u4e49\u6838\u5fc3\u5f02\u5e38\u5bf9\u8c61\uff0c\u5982 ArgumentOutOfRangeException\u3001IndexOutOfRangeException\u3001StackOverflowException \u7b49\u3002\u5176\u4ed6\u547d\u540d\u7a7a\u95f4\u5b9a\u4e49\u53cd\u6620\u8be5\u547d\u540d\u7a7a\u95f4\u884c\u4e3a\u7684\u5f02\u5e38\u3002\u4f8b\u5982\uff0cSystem.Drawing.Print \u5b9a\u4e49\u6253\u5370\u5f02\u5e38\uff0cSystem.IO \u5b9a\u4e49\u57fa\u4e8e\u8f93\u5165\/\u8f93\u51fa\u7684\u5f02\u5e38\uff0cSystem.Data \u5b9a\u4e49\u4ee5\u6570\u636e\u5e93\u4e3a\u4e2d\u5fc3\u7684\u5f02\u5e38\uff0c\u7b49\u7b49\u3002<\/p>\n
\n.NET \u5e73\u53f0\u5f15\u53d1\u7684\u5f02\u5e38\uff08\u9002\u5f53\u5730\uff09\u79f0\u4e3a\u7cfb\u7edf\u5f02\u5e38\u3002\u8fd9\u4e9b\u5f02\u5e38\u901a\u5e38\u88ab\u89c6\u4e3a\u4e0d\u53ef\u6062\u590d\u7684\u81f4\u547d\u9519\u8bef\u3002\u7cfb\u7edf\u5f02\u5e38\u76f4\u63a5\u6d3e\u751f\u81ea\u540d\u4e3a System.SystemException \u7684\u57fa\u7c7b\uff0c\u800c\u57fa\u7c7b\u53c8\u6d3e\u751f\u81ea System.Exception\uff08\u6d3e\u751f\u81ea System.Object\uff09\u3002<\/p>\n
\n{
\n\/\/ Various constructors.
\n}<\/p>\n
\n\u9274\u4e8e System.SystemException \u7c7b\u578b\u9664\u4e86\u4e00\u7ec4\u81ea\u5b9a\u4e49\u6784\u9020\u51fd\u6570\u4e4b\u5916\u4e0d\u4f1a\u6dfb\u52a0\u4efb\u4f55\u529f\u80fd\uff0c\u60a8\u53ef\u80fd\u60f3\u77e5\u9053\u4e3a\u4ec0\u4e48 SystemException \u9996\u5148\u5b58\u5728\u3002\u7b80\u800c\u8a00\u4e4b\uff0c\u5f53\u5f02\u5e38\u7c7b\u578b\u6d3e\u751f\u81ea System.SystemException \u65f6\uff0c\u60a8\u53ef\u4ee5\u786e\u5b9a .NET \u8fd0\u884c\u65f6\u662f\u5f15\u53d1\u5f02\u5e38\u7684\u5b9e\u4f53\uff0c\u800c\u4e0d\u662f\u6b63\u5728\u6267\u884c\u7684\u5e94\u7528\u7a0b\u5e8f\u7684\u4ee3\u7801\u5e93\u3002\u60a8\u53ef\u4ee5\u4f7f\u7528 is \u5173\u952e\u5b57\u975e\u5e38\u7b80\u5355\u5730\u9a8c\u8bc1\u8fd9\u4e00\u70b9\u3002<\/p>\n
\n"NullReferenceException is-a SystemException? : {0}", nullRefEx is SystemException);<\/p>\nApplication-Level Exceptions (System.ApplicationException)<\/h2>\n
\n\u9274\u4e8e\u6240\u6709 .NET \u5f02\u5e38\u90fd\u662f\u7c7b\u7c7b\u578b\uff0c\u60a8\u53ef\u4ee5\u81ea\u7531\u521b\u5efa\u81ea\u5df1\u7684\u7279\u5b9a\u4e8e\u5e94\u7528\u7a0b\u5e8f\u7684\u5f02\u5e38\u3002\u4f46\u662f\uff0c\u7531\u4e8e System.SystemException \u57fa\u7c7b\u8868\u793a\u4ece\u8fd0\u884c\u65f6\u5f15\u53d1\u7684\u5f02\u5e38\uff0c\u56e0\u6b64\u60a8\u53ef\u80fd\u81ea\u7136\u800c\u7136\u5730\u5047\u5b9a\u5e94\u6d3e\u751f\u81ea\u5b9a\u4e49\u5f02\u5e38\u4ece\u7cfb\u7edf\u5f02\u5e38\u7c7b\u578b\u3002\u60a8\u53ef\u4ee5\u8fd9\u6837\u505a\uff0c\u4f46\u60a8\u53ef\u4ee5\u4ece\u7cfb\u7edf\u6d3e\u751f\u3002\u5e94\u7528\u7a0b\u5e8f\u5f02\u5e38\u7c7b\u3002<\/p>\n
\n{
\n\/\/ Various constructors.
\n}<\/p>\n
\n\u4e0e SystemException \u4e00\u6837\uff0cApplicationException \u9664\u4e86\u4e00\u7ec4\u6784\u9020\u51fd\u6570\u4e4b\u5916\uff0c\u4e0d\u4f1a\u5b9a\u4e49\u4efb\u4f55\u5176\u4ed6\u6210\u5458\u3002\u4ece\u529f\u80fd\u4e0a\u8bb2\uff0cSystem.ApplicationException \u7684\u552f\u4e00\u76ee\u7684\u662f\u8bc6\u522b\u9519\u8bef\u7684\u6e90\u3002\u5904\u7406\u4ece System.ApplicationException \u6d3e\u751f\u7684\u5f02\u5e38\u65f6\uff0c\u53ef\u4ee5\u5047\u5b9a\u5f02\u5e38\u662f\u7531\u6267\u884c\u5e94\u7528\u7a0b\u5e8f\u7684\u4ee3\u7801\u5e93\u5f15\u53d1\u7684\uff0c\u800c\u4e0d\u662f\u7531 .NET Core \u57fa\u7c7b\u5e93\u6216 .NET \u8fd0\u884c\u65f6\u5f15\u64ce\u5f15\u53d1\u7684\u3002<\/p>\nBuilding Custom Exceptions, Take 1<\/h2>\n
\n\u867d\u7136\u60a8\u59cb\u7ec8\u53ef\u4ee5\u629b\u51fa System.Exception \u7684\u5b9e\u4f8b\u6765\u53d1\u51fa\u8fd0\u884c\u65f6\u9519\u8bef\u7684\u4fe1\u53f7\uff08\u5982\u7b2c\u4e00\u4e2a\u793a\u4f8b\u4e2d\u6240\u793a\uff09\uff0c\u4f46\u6709\u65f6\u6784\u5efa\u4e00\u4e2a\u8868\u793a\u5f53\u524d\u95ee\u9898\u7684\u552f\u4e00\u8be6\u7ec6\u4fe1\u606f\u7684\u5f3a\u7c7b\u578b\u5f02\u5e38\u662f\u6709\u5229\u7684\u3002\u4f8b\u5982\uff0c\u5047\u8bbe\u60a8\u8981\u6784\u5efa\u4e00\u4e2a\u81ea\u5b9a\u4e49\u5f02\u5e38\uff08\u540d\u4e3aCarIsDeadException\uff09\u6765\u8868\u793a\u52a0\u901f\u6ce8\u5b9a\u8981\u5931\u8d25\u7684\u6c7d\u8f66\u7684\u9519\u8bef\u3002\u7b2c\u4e00\u6b65\u662f\u4ece System.Exception\/System.ApplicationException \u6d3e\u751f\u4e00\u4e2a\u65b0\u7c7b\uff08\u6309\u7167\u60ef\u4f8b\uff0c\u6240\u6709\u5f02\u5e38\u7c7b\u540d\u90fd\u4ee5 Exception \u540e\u7f00\u7ed3\u5c3e\uff09\u3002<\/p>\n
\n\u8bf7\u6ce8\u610f\uff0c\u4f5c\u4e3a\u4e00\u9879\u89c4\u5219\uff0c\u6240\u6709\u81ea\u5b9a\u4e49\u5f02\u5e38\u7c7b\u90fd\u5e94\u5b9a\u4e49\u4e3a\u516c\u5171\u7c7b\uff08\u56de\u60f3\u4e00\u4e0b\uff0c\u975e\u5d4c\u5957\u7c7b\u578b\u7684\u9ed8\u8ba4\u8bbf\u95ee\u4fee\u9970\u7b26\u662f\u5185\u90e8\u7684\uff09\u3002\u539f\u56e0\u662f\u5f02\u5e38\u901a\u5e38\u5728\u7a0b\u5e8f\u96c6\u8fb9\u754c\u4e4b\u5916\u4f20\u9012\uff0c\u56e0\u6b64\u8c03\u7528\u4ee3\u7801\u5e93\u5e94\u8be5\u53ef\u4ee5\u8bbf\u95ee\u3002<\/p>\n
\n\u521b\u5efa\u4e00\u4e2a\u540d\u4e3a CustomException \u7684\u65b0\u63a7\u5236\u53f0\u5e94\u7528\u7a0b\u5e8f\u9879\u76ee\uff0c\u5c06\u4ee5\u524d\u7684 Car.cs \u548c Radio.cs \u6587\u4ef6\u590d\u5236\u5230\u65b0\u9879\u76ee\u4e2d\uff0c\u5e76\u5c06\u5b9a\u4e49 Car \u548c Radio \u7c7b\u578b\u7684\u547d\u540d\u7a7a\u95f4\u4ece SimpleException \u66f4\u6539\u4e3a CustomException\u3002\u63a5\u4e0b\u6765\uff0c\u6dfb\u52a0\u4e00\u4e2a\u540d\u4e3a CarIsDeadException \u7684\u65b0\u6587\u4ef6.cs\u5e76\u6dfb\u52a0\u4ee5\u4e0b\u7c7b\u5b9a\u4e49\uff1a<\/p>\n
\n\/\/ This custom exception describes the details of the car-is-dead condition.
\n\/\/ (Remember, you can also simply extend Exception.) public class CarIsDeadException : ApplicationException
\n{
\n}<\/p>\n
\n\u4e0e\u4efb\u4f55\u7c7b\u4e00\u6837\uff0c\u60a8\u53ef\u4ee5\u81ea\u7531\u5730\u5305\u542b\u4efb\u610f\u6570\u91cf\u7684\u81ea\u5b9a\u4e49\u6210\u5458\uff0c\u8fd9\u4e9b\u6210\u5458\u53ef\u4ee5\u5728\u8c03\u7528\u903b\u8f91\u7684 catch \u5757\u4e2d\u8c03\u7528\u3002\u60a8\u8fd8\u53ef\u4ee5\u81ea\u7531\u8986\u76d6\u7236\u7c7b\u5b9a\u4e49\u7684\u4efb\u4f55\u865a\u62df\u6210\u5458\u3002\u4f8b\u5982\uff0c\u60a8\u53ef\u4ee5\u901a\u8fc7\u91cd\u5199\u865a\u62df\u6d88\u606f\u5c5e\u6027\u6765\u5b9e\u73b0 CarIsDeadException\u3002<\/p>\n
\n\u540c\u6837\uff0c\u6784\u9020\u51fd\u6570\u5141\u8bb8\u53d1\u9001\u65b9\u4f20\u5165\u65f6\u95f4\u6233\u548c\u9519\u8bef\u539f\u56e0\uff0c\u800c\u4e0d\u662f\u5728\u5f15\u53d1\u5f02\u5e38\u65f6\u586b\u5145\u6570\u636e\u5b57\u5178\uff08\u901a\u8fc7 Data \u5c5e\u6027\uff09\u3002\u6700\u540e\uff0c\u53ef\u4ee5\u4f7f\u7528\u5f3a\u7c7b\u578b\u5c5e\u6027\u83b7\u53d6\u65f6\u95f4\u6233\u6570\u636e\u548c\u9519\u8bef\u539f\u56e0\u3002<\/p>\n
\n{
\nprivate string _messageDetails = String.Empty; public DateTime ErrorTimeStamp {get; set;} public string CauseOfError {get; set;}<\/p>\n
\npublic CarIsDeadException(string message, string cause, DateTime time)
\n{
\n_messageDetails = message; CauseOfError = cause; ErrorTimeStamp = time;
\n}<\/p>\n
\n=> $"Car Error Message: {_messageDetails}";
\n}<\/p>\n
\n\u5728\u8fd9\u91cc\uff0cCarIsDeadException \u7c7b\u7ef4\u62a4\u4e00\u4e2a\u79c1\u6709\u5b57\u6bb5 \uff08_messageDetails\uff09\uff0c\u8be5\u5b57\u6bb5\u8868\u793a\u6709\u5173\u5f53\u524d\u5f02\u5e38\u7684\u6570\u636e\uff0c\u53ef\u4ee5\u4f7f\u7528\u81ea\u5b9a\u4e49\u6784\u9020\u51fd\u6570\u8fdb\u884c\u8bbe\u7f6e\u3002\u4ece Accelerate\uff08\uff09 \u65b9\u6cd5\u5f15\u53d1\u6b64\u5f02\u5e38\u975e\u5e38\u7b80\u5355\u3002\u53ea\u9700\u5206\u914d\u3001\u914d\u7f6e\u548c\u629b\u51fa CarIsDeadException \u7c7b\u578b\uff0c\u800c\u4e0d\u662f System.Exception\u3002<\/p>\n
\n{
\n...
\nthrow new CarIsDeadException(
\n$"{PetName} has overheated!",
\n"You have a lead foot", DateTime.Now )
\n{
\nHelpLink = "http:\/\/www.CarsRUs.com<\/a><\/a><\/a>",
\n};
\n...
\n}<\/p>\n
\n\u8981\u6355\u83b7\u6b64\u4f20\u5165\u5f02\u5e38\uff0c\u73b0\u5728\u53ef\u4ee5\u66f4\u65b0\u6355\u83b7\u8303\u56f4\u4ee5\u6355\u83b7\u7279\u5b9a\u7684CarIsDeadException\u7c7b\u578b\uff08\u4f46\u662f\uff0c\u9274\u4e8eCarIsDeadException\u201c\u662f-a\u201dSystem.Exception\uff0c\u4ecd\u7136\u5141\u8bb8\u6355\u83b7System.Exception\uff09\u3002<\/p>\n
\n{
\n\/\/ Trip exception. myCar.Accelerate(50);
\n}
\ncatch (CarIsDeadException e)<\/p>\n
\nConsole.WriteLine(e.Message); Console.WriteLine(e.ErrorTimeStamp); Console.WriteLine(e.CauseOfError);
\n}
\nConsole.ReadLine();<\/p>\n
\n\u56e0\u6b64\uff0c\u73b0\u5728\u60a8\u5df2\u7ecf\u4e86\u89e3\u4e86\u6784\u5efa\u81ea\u5b9a\u4e49\u5f02\u5e38\u7684\u57fa\u672c\u8fc7\u7a0b\uff0c\u662f\u65f6\u5019\u57fa\u4e8e\u8fd9\u4e9b\u77e5\u8bc6\u8fdb\u884c\u6784\u5efa\u4e86\u3002<\/p>\nBuilding Custom Exceptions, Take 2<\/h3>\n
\n\u5f53\u524d\u7684 CarIsDeadException \u7c7b\u578b\u5df2\u8986\u76d6\u865a\u62df System.Exception.Message \u5c5e\u6027\u4ee5\u914d\u7f6e\u81ea\u5b9a\u4e49\u9519\u8bef\u6d88\u606f\uff0c\u5e76\u63d0\u4f9b\u4e86\u4e24\u4e2a\u81ea\u5b9a\u4e49\u5c5e\u6027\u6765\u8003\u8651\u5176\u4ed6\u6570\u636e\u4f4d\u3002\u4f46\u662f\uff0c\u5b9e\u9645\u4e0a\uff0c\u60a8\u4e0d\u9700\u8981\u91cd\u5199\u865a\u62df Message \u5c5e\u6027\uff0c\u56e0\u4e3a\u60a8\u53ea\u9700\u5c06\u4f20\u5165\u6d88\u606f\u4f20\u9012\u7ed9\u7236\u7ea7\u7684\u6784\u9020\u51fd\u6570\uff0c\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n
\n{
\npublic DateTime ErrorTimeStamp { get; set; } public string CauseOfError { get; set; }<\/p>\n
\npublic CarIsDeadException(string message, string cause, DateTime time)
\n:base(message)
\n{
\nCauseOfError = cause;
\nErrorTimeStamp = time;
\n}
\n}<\/p>\n
\n\u8bf7\u6ce8\u610f\uff0c\u8fd9\u6b21\u60a8\u6ca1\u6709\u5b9a\u4e49\u4e00\u4e2a\u5b57\u7b26\u4e32\u53d8\u91cf\u6765\u8868\u793a\u6d88\u606f\uff0c\u4e5f\u6ca1\u6709\u91cd\u5199 Message \u5c5e\u6027\u3002\u76f8\u53cd\uff0c\u60a8\u53ea\u9700\u5c06\u53c2\u6570\u4f20\u9012\u7ed9\u57fa\u7c7b\u6784\u9020\u51fd\u6570\u3002\u901a\u8fc7\u8fd9\u79cd\u8bbe\u8ba1\uff0c\u81ea\u5b9a\u4e49\u5f02\u5e38\u7c7b\u53ea\u4e0d\u8fc7\u662f\u4ece System \u6d3e\u751f\u7684\u552f\u4e00\u547d\u540d\u7c7b\u3002ApplicationException\uff08\u5982\u679c\u9002\u7528\uff0c\u5177\u6709\u5176\u4ed6\u5c5e\u6027\uff09\uff0c\u6ca1\u6709\u4efb\u4f55\u57fa\u7c7b\u91cd\u5199\u3002<\/p>\n
\n\u5982\u679c\u5927\u591a\u6570\uff08\u5982\u679c\u4e0d\u662f\u5168\u90e8\uff09\u81ea\u5b9a\u4e49\u5f02\u5e38\u7c7b\u90fd\u9075\u5faa\u8fd9\u79cd\u7b80\u5355\u7684\u6a21\u5f0f\uff0c\u8bf7\u4e0d\u8981\u611f\u5230\u60ca\u8bb6\u3002\u5f88\u591a\u65f6\u5019\uff0c\u81ea\u5b9a\u4e49\u5f02\u5e38\u7684\u4f5c\u7528\u4e0d\u4e00\u5b9a\u662f\u63d0\u4f9b\u4ece\u57fa\u7c7b\u7ee7\u627f\u7684\u529f\u80fd\u4e4b\u5916\u7684\u5176\u4ed6\u529f\u80fd\uff0c\u800c\u662f\u63d0\u4f9b\u660e\u786e\u6807\u8bc6\u9519\u8bef\u6027\u8d28\u7684\u5f3a\u540d\u79f0\u7c7b\u578b\uff0c\u4ee5\u4fbf\u5ba2\u6237\u7aef\u53ef\u4ee5\u4e3a\u4e0d\u540c\u7c7b\u578b\u7684\u5f02\u5e38\u63d0\u4f9b\u4e0d\u540c\u7684\u5904\u7406\u7a0b\u5e8f\u903b\u8f91\u3002<\/p>\nBuilding Custom Exceptions, Take 3<\/h3>\n
\n\u5982\u679c\u8981\u751f\u6210\u4e00\u4e2a\u771f\u6b63\u539f\u59cb\u4e14\u6b63\u786e\u7684\u81ea\u5b9a\u4e49\u5f02\u5e38\u7c7b\uff0c\u5219\u9700\u8981\u786e\u4fdd\u81ea\u5b9a\u4e49\u5f02\u5e38\u6267\u884c\u4ee5\u4e0b\u64cd\u4f5c\uff1a
\n\u2022 Derives from Exception\/ApplicationException
\n\u6d3e\u751f\u81ea\u5f02\u5e38\/\u5e94\u7528\u7a0b\u5e8f\u5f02\u5e38
\n\u2022 Defines a default constructor
\n\u5b9a\u4e49\u9ed8\u8ba4\u6784\u9020\u51fd\u6570
\n\u2022Defines a constructor that sets the inherited Message property
\n\u5b9a\u4e49\u8bbe\u7f6e\u7ee7\u627f\u7684 Message \u5c5e\u6027\u7684\u6784\u9020\u51fd\u6570
\n\u2022Defines a constructor to handle \u201cinner exceptions\u201d
\n\u5b9a\u4e49\u7528\u4e8e\u5904\u7406\u201c\u5185\u90e8\u5f02\u5e38\u201d\u7684\u6784\u9020\u51fd\u6570<\/p>\n
\n\u4e3a\u4e86\u5b8c\u6210\u5bf9\u751f\u6210\u81ea\u5b9a\u4e49\u5f02\u5e38\u7684\u68c0\u67e5\uff0c\u4e0b\u9762\u662f CarIsDeadException \u7684\u6700\u7ec8\u8fed\u4ee3\uff0c\u5b83\u8003\u8651\u4e86\u8fd9\u4e9b\u7279\u6b8a\u6784\u9020\u51fd\u6570\u4e2d\u7684\u6bcf\u4e00\u4e2a\uff08\u5c5e\u6027\u5982\u524d\u9762\u7684\u793a\u4f8b\u6240\u793a\uff09\uff1a<\/p>\n
\n{
\nprivate string _messageDetails = String.Empty; public DateTime ErrorTimeStamp {get; set;} public string CauseOfError {get; set;}<\/p>\n
\npublic CarIsDeadException(string cause, DateTime time) : this(cause,time,string.Empty)
\n{
\n}
\npublic CarIsDeadException(string cause, DateTime time, string message) : this(cause,time,message, null)
\n{
\n}<\/p>\n
\n: base(message, inner)
\n{
\nCauseOfError = cause;
\nErrorTimeStamp = time;
\n}
\n}<\/p>\n
\n\u901a\u8fc7\u5bf9\u81ea\u5b9a\u4e49\u5f02\u5e38\u7684\u6b64\u66f4\u65b0\uff0c\u5c06 Accelerate\uff08\uff09 \u65b9\u6cd5\u66f4\u65b0\u4e3a\u4ee5\u4e0b\u5185\u5bb9\uff1a<\/p>\n
\n{
\nHelpLink = "http:\/\/www.CarsRUs.com<\/a><\/a><\/a>",
\n};<\/p>\n
\n\u9274\u4e8e\u751f\u6210\u9075\u5faa .NET Core \u6700\u4f73\u505a\u6cd5\u7684\u81ea\u5b9a\u4e49\u5f02\u5e38\u5b9e\u9645\u4e0a\u4ec5\u5728\u540d\u79f0\u4e0a\u6709\u6240\u4e0d\u540c\uff0c\u60a8\u4f1a\u5f88\u9ad8\u5174\u77e5\u9053 Visual Studio \u63d0\u4f9b\u4e86\u4e00\u4e2a\u540d\u4e3a Exception \u7684\u4ee3\u7801\u6bb5\u6a21\u677f\uff0c\u8be5\u6a21\u677f\u5c06\u81ea\u52a8\u751f\u6210\u7b26\u5408 .NET \u6700\u4f73\u505a\u6cd5\u7684\u65b0\u5f02\u5e38\u7c7b\u3002\u8981\u6fc0\u6d3b\u5b83\uff0c\u8bf7\u5728\u7f16\u8f91\u5668\u4e2d\u952e\u5165 exc \u5e76\u6309 Tab \u952e\uff08\u5728 Visual Studio \u4e2d\uff0c\u6309 Tab \u952e\u4e24\u6b21\uff09\u3002<\/p>\nMultiple Exceptions<\/h2>\n
\nC# Console Application project named ProcessMultipleExceptions; copy the Car.cs, Radio.cs, and CarIsDeadException.cs files from the previous CustomException example into the new project, and update your namespace names accordingly.
\n\u5728\u6700\u7b80\u5355\u7684\u5f62\u5f0f\u4e2d\uff0ctry \u5757\u53ea\u6709\u4e00\u4e2a catch \u5757\u3002\u4f46\u662f\uff0c\u5728\u73b0\u5b9e\u4e2d\uff0c\u60a8\u7ecf\u5e38\u4f1a\u9047\u5230 try \u5757\u4e2d\u7684\u8bed\u53e5\u53ef\u80fd\u4f1a\u89e6\u53d1\u8bb8\u591a\u53ef\u80fd\u7684\u5f02\u5e38\u7684\u60c5\u51b5\u3002\u521b\u5efa\u4e00\u4e2a\u65b0\u7684\u540d\u4e3a ProcessMultipleExceptions \u7684 C# \u63a7\u5236\u53f0\u5e94\u7528\u7a0b\u5e8f\u9879\u76ee;\u5c06 Car.cs\u3001Radio.cs \u548c CarIsDeadException.cs \u6587\u4ef6\u4ece\u4ee5\u524d\u7684 CustomException \u793a\u4f8b\u590d\u5236\u5230\u65b0\u9879\u76ee\u4e2d\uff0c\u5e76\u76f8\u5e94\u5730\u66f4\u65b0\u547d\u540d\u7a7a\u95f4\u540d\u79f0\u3002<\/p>\n
\n\u73b0\u5728\uff0c\u66f4\u65b0 Car \u7684 Accelerate\uff08\uff09 \u65b9\u6cd5\uff0c\u4ee5\u4fbf\u5728\u4f20\u9012\u65e0\u6548\u53c2\u6570\uff08\u53ef\u4ee5\u5047\u5b9a\u8be5\u53c2\u6570\u5c0f\u4e8e\u96f6\u7684\u4efb\u4f55\u503c\uff09\u65f6\u4e5f\u629b\u51fa\u9884\u5b9a\u4e49\u7684\u57fa\u7c7b\u5e93 ArgumentOutOfRangeException\u3002\u8bf7\u6ce8\u610f\uff0c\u6b64\u5f02\u5e38\u7c7b\u7684\u6784\u9020\u51fd\u6570\u5c06\u6709\u95ee\u9898\u7684\u53c2\u6570\u7684\u540d\u79f0\u4f5c\u4e3a\u7b2c\u4e00\u4e2a\u5b57\u7b26\u4e32\uff0c\u540e\u8ddf\u63cf\u8ff0\u9519\u8bef\u7684\u6d88\u606f\u3002<\/p>\n
\n{
\nif (delta < 0)
\n{
\nthrow new ArgumentOutOfRangeException(nameof(delta), "Speed must be greater than zero");
\n}
\n...
\n}<\/p>\n
\n\u6ce8\u610f nameof\uff08\uff09 \u8fd0\u7b97\u7b26\u8fd4\u56de\u4e00\u4e2a\u8868\u793a\u5bf9\u8c61\u540d\u79f0\u7684\u5b57\u7b26\u4e32\uff0c\u5728\u672c\u4f8b\u4e2d\u4e3a\u53d8\u91cf delta\u3002\u5f53\u9700\u8981\u5b57\u7b26\u4e32\u7248\u672c\u65f6\uff0c\u8fd9\u662f\u5f15\u7528 C# \u5bf9\u8c61\u3001\u65b9\u6cd5\u548c\u53d8\u91cf\u7684\u66f4\u5b89\u5168\u65b9\u6cd5\u3002<\/p>\n
\ncatch \u903b\u8f91\u73b0\u5728\u53ef\u4ee5\u4e13\u95e8\u54cd\u5e94\u6bcf\u79cd\u7c7b\u578b\u7684\u5f02\u5e38\u3002<\/p>\n
\ntry
\n{
\n\/\/ Trip Arg out of range exception. myCar.Accelerate(-10);
\n}
\ncatch (CarIsDeadException e)
\n{
\nConsole.WriteLine(e.Message);
\n}
\ncatch (ArgumentOutOfRangeException e)
\n{
\nConsole.WriteLine(e.Message);
\n}
\nConsole.ReadLine();<\/p>\n
\n\u521b\u4f5c\u591a\u4e2a catch \u5757\u65f6\uff0c\u5fc5\u987b\u6ce8\u610f\uff0c\u5f53\u5f15\u53d1\u5f02\u5e38\u65f6\uff0c\u5b83\u5c06\u7531\u7b2c\u4e00\u4e2a\u9002\u5f53\u7684 catch \u5904\u7406\u3002\u4e3a\u4e86\u51c6\u786e\u8bf4\u660e\u201c\u7b2c\u4e00\u4e2a\u9002\u5f53\u7684\u201d\u6355\u83b7\u7684\u542b\u4e49\uff0c\u5047\u8bbe\u60a8\u4f7f\u7528\u5c1d\u8bd5\u5904\u7406\u6240\u6709\u6355\u83b7\u7684\u9644\u52a0\u6355\u83b7\u8303\u56f4\u6765\u6539\u9020\u524d\u9762\u7684\u903b\u8f91CarIsDeadException \u548c ArgumentOutOfRangeException \u4e4b\u5916\u7684\u5f02\u5e38\uff0c\u901a\u8fc7\u6355\u83b7\u4e00\u822c\u7cfb\u7edf\u3002\u4f8b\u5916\u60c5\u51b5\u5982\u4e0b\uff1a<\/p>\n
\nConsole.WriteLine(" Handling Multiple Exceptions <\/em><\/strong><\/strong>\\n"); Car myCar = new Car("Rusty", 90);<\/p>\n
\n{
\n\/\/ Trigger an argument out of range exception. myCar.Accelerate(-10);
\n}
\ncatch(Exception e)
\n{
\n\/\/ Process all other exceptions? Console.WriteLine(e.Message);
\n}
\ncatch (CarIsDeadException e)
\n{
\nConsole.WriteLine(e.Message);
\n}
\ncatch (ArgumentOutOfRangeException e)
\n{
\nConsole.WriteLine(e.Message);
\n}
\nConsole.ReadLine();<\/p>\n
\n\u6b64\u5f02\u5e38\u5904\u7406\u903b\u8f91\u751f\u6210\u7f16\u8bd1\u65f6\u9519\u8bef\u3002\u95ee\u9898\u5728\u4e8e\uff0c\u7b2c\u4e00\u4e2a catch \u5757\u53ef\u4ee5\u5904\u7406\u4ece System.Exception \u6d3e\u751f\u7684\u4efb\u4f55\u5185\u5bb9\uff08\u7ed9\u5b9a\u201cis-a\u201d\u5173\u7cfb\uff09\uff0c\u5305\u62ec CarIsDeadException \u548c ArgumentOutOfRangeException \u7c7b\u578b\u3002\u56e0\u6b64\uff0c\u6700\u540e\u4e24\u4e2a\u6355\u83b7\u5757\u662f\u65e0\u6cd5\u8bbf\u95ee\u7684\uff01<\/p>\n
\n\u8981\u8bb0\u4f4f\u7684\u7ecf\u9a8c\u6cd5\u5219\u662f\u786e\u4fdd\u4f60\u7684 catch \u5757\u7684\u7ed3\u6784\u4f7f\u5f97\u7b2c\u4e00\u4e2a catch \u662f\u6700\u5177\u4f53\u7684\u5f02\u5e38\uff08\u5373\u5f02\u5e38\u7c7b\u578b\u7ee7\u627f\u94fe\u4e2d\u6d3e\u751f\u6700\u591a\u7684\u7c7b\u578b\uff09\uff0c\u5c06\u6700\u7ec8\u7684 catch \u7559\u7ed9\u6700\u4e00\u822c\u7684\uff08\u5373\uff0c\u7ed9\u5b9a\u5f02\u5e38\u7ee7\u627f\u94fe\u7684\u57fa\u7c7b\uff0c\u5728\u672c\u4f8b\u4e2d\u4e3a System.Exception\uff09\u3002<\/p>\n
\nArgumentOutOfRangeException, you could write the following:
\n\u56e0\u6b64\uff0c\u5982\u679c\u4f60\u60f3\u5b9a\u4e49\u4e00\u4e2a\u6355\u83b7\u5757\u6765\u5904\u7406CarIsDeadException\u4e4b\u5916\u7684\u4efb\u4f55\u9519\u8bef\uff0c\u5e76\u4e14ArgumentOutOfRangeException\uff0c\u4f60\u53ef\u4ee5\u5199\u4ee5\u4e0b\u5185\u5bb9\uff1a<\/p>\n
\nConsole.WriteLine(" Handling Multiple Exceptions <\/em><\/strong><\/strong>\\n"); Car myCar = new Car("Rusty", 90);
\ntry
\n{
\n\/\/ Trigger an argument out of range exception. myCar.Accelerate(-10);
\n}
\ncatch (CarIsDeadException e)
\n{
\nConsole.WriteLine(e.Message);
\n}
\ncatch (ArgumentOutOfRangeException e)
\n{
\nConsole.WriteLine(e.Message);
\n}<\/p>\n
\n\/\/ beyond CarIsDeadException or
\n\/\/ ArgumentOutOfRangeException. catch (Exception e)
\n{
\nConsole.WriteLine(e.Message);
\n}
\nConsole.ReadLine();<\/p>\n
\n\u6ce8\u610f \u5728\u53ef\u80fd\u7684\u60c5\u51b5\u4e0b\uff0c\u59cb\u7ec8\u503e\u5411\u4e8e\u6355\u83b7\u7279\u5b9a\u7684\u5f02\u5e38\u7c7b\uff0c\u800c\u4e0d\u662f\u4e00\u822c\u7684 System.Exception\u3002\u867d\u7136\u5b83\u53ef\u80fd\u5728\u77ed\u671f\u5185\u770b\u8d77\u6765\u4f7f\u751f\u6d3b\u53d8\u5f97\u7b80\u5355\uff08\u4f60\u53ef\u80fd\u4f1a\u60f3\u201c\u554a\uff01\u8fd9\u6293\u4f4f\u4e86\u6211\u4e0d\u5173\u5fc3\u7684\u6240\u6709\u5176\u4ed6\u4e8b\u60c5\u201c\uff09\uff0c\u4ece\u957f\u8fdc\u6765\u770b\uff0c\u4f60\u6700\u7ec8\u53ef\u80fd\u4f1a\u9047\u5230\u5947\u602a\u7684\u8fd0\u884c\u65f6\u5d29\u6e83\uff0c\u56e0\u4e3a\u66f4\u4e25\u91cd\u7684\u9519\u8bef\u6ca1\u6709\u5728\u4f60\u7684\u4ee3\u7801\u4e2d\u76f4\u63a5\u5904\u7406\u3002\u8bf7\u8bb0\u4f4f\uff0c\u5904\u7406System.Exception\u7684\u6700\u540e\u4e00\u4e2a\u6355\u83b7\u5757\u786e\u5b9e\u975e\u5e38\u901a\u7528\u3002<\/p>\nGeneral catch Statements<\/h2>\n
\nC# \u8fd8\u652f\u6301\u201c\u5e38\u89c4\u201d\u6355\u83b7\u8303\u56f4\uff0c\u8be5\u8303\u56f4\u4e0d\u663e\u5f0f\u63a5\u6536\u7ed9\u5b9a\u6210\u5458\u5f15\u53d1\u7684\u5f02\u5e38\u5bf9\u8c61\u3002<\/p>\n
\nConsole.WriteLine(" Handling Multiple Exceptions <\/em><\/strong><\/strong>\\n"); Car myCar = new Car("Rusty", 90);
\ntry
\n{
\nmyCar.Accelerate(90);
\n}
\ncatch
\n{
\nConsole.WriteLine("Something bad happened...");
\n}
\nConsole.ReadLine();<\/p>\n
\n\u663e\u7136\uff0c\u8fd9\u4e0d\u662f\u5904\u7406\u5f02\u5e38\u7684\u6700\u6709\u7528\u7684\u65b9\u6cd5\uff0c\u56e0\u4e3a\u60a8\u65e0\u6cd5\u83b7\u53d6\u6709\u5173\u6240\u53d1\u751f\u9519\u8bef\u7684\u6709\u610f\u4e49\u7684\u6570\u636e\uff08\u4f8b\u5982\u65b9\u6cd5\u540d\u79f0\u3001\u8c03\u7528\u5806\u6808\u6216\u81ea\u5b9a\u4e49\u6d88\u606f\uff09\u3002\u5c3d\u7ba1\u5982\u6b64\uff0cC# \u786e\u5b9e\u5141\u8bb8\u8fd9\u6837\u7684\u6784\u9020\uff0c\u5f53\u60a8\u5e0c\u671b\u4ee5\u5e38\u89c4\u65b9\u5f0f\u5904\u7406\u6240\u6709\u9519\u8bef\u65f6\uff0c\u8fd9\u4f1a\u5f88\u6709\u5e2e\u52a9\u3002<\/p>\nRethrowing Exceptions<\/h2>\n
\n\u6355\u83b7\u5f02\u5e38\u65f6\uff0c\u5141\u8bb8 try \u5757\u4e2d\u7684\u903b\u8f91\u5c06\u5f02\u5e38\u91cd\u65b0\u629b\u51fa\u5230\u8c03\u7528\u5806\u6808\u4e2d\u5230\u524d\u4e00\u4e2a\u8c03\u7528\u65b9\u3002\u4e3a\u6b64\uff0c\u53ea\u9700\u5728 catch \u5757\u4e2d\u4f7f\u7528 throw\uff08\uff09\u3002 \u8fd9\u4f1a\u5c06\u5f02\u5e38\u4f20\u9012\u5230\u8c03\u7528\u903b\u8f91\u94fe\u4e0a\uff0c\u5982\u679c\u60a8\u7684 catch \u5757\u53ea\u80fd\u90e8\u5206\u5904\u7406\u624b\u5934\u7684\u9519\u8bef\uff0c\u8fd9\u4f1a\u5f88\u6709\u5e2e\u52a9\u3002<\/p>\n
\n...
\ntry
\n{
\n\/\/ Speed up car logic...
\n}
\ncatch(CarIsDeadException e)
\n{
\n\/\/ Do any partial processing of this error and pass the buck. throw;
\n}
\n...<\/p>\n
\n\u8bf7\u6ce8\u610f\uff0c\u5728\u6b64\u793a\u4f8b\u4ee3\u7801\u4e2d\uff0cCarIsDeadException \u7684\u6700\u7ec8\u63a5\u6536\u65b9\u662f .NET \u8fd0\u884c\u65f6\uff0c\u56e0\u4e3a\u5b83\u662f\u91cd\u65b0\u5f15\u53d1\u5f02\u5e38\u7684\u9876\u7ea7\u8bed\u53e5\u3002\u56e0\u6b64\uff0c\u6700\u7ec8\u7528\u6237\u4f1a\u770b\u5230\u7cfb\u7edf\u63d0\u4f9b\u7684\u9519\u8bef\u5bf9\u8bdd\u6846\u3002\u901a\u5e38\uff0c\u60a8\u53ea\u4f1a\u5c06\u90e8\u5206\u5904\u7406\u7684\u5f02\u5e38\u91cd\u65b0\u5f15\u53d1\u7ed9\u80fd\u591f\u66f4\u4f18\u96c5\u5730\u5904\u7406\u4f20\u5165\u5f02\u5e38\u7684\u8c03\u7528\u65b9\u3002<\/p>\n
\nthe original exception object (with all its original information). Doing so preserves the context of the original target.
\n\u8fd8\u8981\u6ce8\u610f\u7684\u662f\uff0c\u4f60\u6ca1\u6709\u663e\u5f0f\u5730\u91cd\u65b0\u629b\u51fa CarIsDeadException \u5bf9\u8c61\uff0c\u800c\u662f\u5728\u6ca1\u6709\u53c2\u6570\u7684\u60c5\u51b5\u4e0b\u4f7f\u7528 throw\uff08\uff09\u3002 \u60a8\u6ca1\u6709\u521b\u5efa\u65b0\u7684\u5f02\u5e38\u5bf9\u8c61;\u4f60\u53ea\u662f\u5728\u91cd\u65b0\u6295\u63b7\u539f\u59cb\u5f02\u5e38\u5bf9\u8c61\uff08\u53ca\u5176\u6240\u6709\u539f\u59cb\u4fe1\u606f\uff09\u3002\u8fd9\u6837\u505a\u53ef\u4ee5\u4fdd\u7559\u539f\u59cb\u76ee\u6807\u7684\u4e0a\u4e0b\u6587\u3002<\/p>\nInner Exceptions<\/h2>\n
\n\u6b63\u5982\u60a8\u53ef\u80fd\u6000\u7591\u7684\u90a3\u6837\uff0c\u5b8c\u5168\u6709\u53ef\u80fd\u5728\u5904\u7406\u53e6\u4e00\u4e2a\u5f02\u5e38\u65f6\u89e6\u53d1\u5f02\u5e38\u3002\u4f8b\u5982\uff0c\u5047\u8bbe\u60a8\u6b63\u5728\u7279\u5b9a\u7684 catch \u8303\u56f4\u5185\u5904\u7406 CarIsDeadException\uff0c\u5e76\u4e14\u5728\u6b64\u8fc7\u7a0b\u4e2d\u5c1d\u8bd5\u5c06\u5806\u6808\u8ddf\u8e2a\u8bb0\u5f55\u5230 C\uff1a \u9a71\u52a8\u5668\u4e0a\u540d\u4e3a carErrors \u7684\u6587\u4ef6.txt \uff08\u9690\u5f0f\u5168\u5c40 using \u8bed\u53e5\u6388\u4e88\u60a8\u8bbf\u95ee System.IO \u547d\u540d\u7a7a\u95f4\u53ca\u5176\u4ee5 I\/O \u4e3a\u4e2d\u5fc3\u7684\u7c7b\u578b\uff09\u3002<\/p>\n
\n{
\n\/\/ Attempt to open a file named carErrors.txt on the C drive. FileStream fs = File.Open(@"C:\\carErrors.txt", FileMode.Open);
\n...
\n}<\/p>\n
\n\u73b0\u5728\uff0c\u5982\u679c\u6307\u5b9a\u7684\u6587\u4ef6\u4e0d\u5728 C\uff1a \u9a71\u52a8\u5668\u4e0a\uff0c\u5219\u8c03\u7528 File.Open\uff08\uff09 \u4f1a\u5bfc\u81f4 FileNotFoundException\uff01\u5728\u672c\u4e66\u7684\u540e\u9762\u90e8\u5206\uff0c\u60a8\u5c06\u4e86\u89e3\u6709\u5173 System.IO \u547d\u540d\u7a7a\u95f4\u7684\u6240\u6709\u4fe1\u606f\uff0c\u60a8\u5c06\u5728\u5176\u4e2d\u4e86\u89e3\u5982\u4f55\u5728\u5c1d\u8bd5\u6253\u5f00\u6587\u4ef6\u4e4b\u524d\u4ee5\u7f16\u7a0b\u65b9\u5f0f\u786e\u5b9a\u786c\u76d8\u9a71\u52a8\u5668\u4e0a\u662f\u5426\u5b58\u5728\u6587\u4ef6\uff08\u4ece\u800c\u5b8c\u5168\u907f\u514d\u5f02\u5e38\uff09\u3002\u4f46\u662f\uff0c\u4e3a\u4e86\u7ee7\u7eed\u5173\u6ce8\u5f02\u5e38\u4e3b\u9898\uff0c\u8bf7\u5047\u8bbe\u5df2\u5f15\u53d1\u5f02\u5e38\u3002<\/p>\n
\n\u73b0\u5728\uff0c\u5982\u679c\u6307\u5b9a\u7684\u6587\u4ef6\u4e0d\u5728 C\uff1a \u9a71\u52a8\u5668\u4e0a\uff0c\u5219\u8c03\u7528 File.Open\uff08\uff09 \u4f1a\u5bfc\u81f4 FileNotFoundException\uff01\u5728\u672c\u4e66\u7684\u540e\u9762\u90e8\u5206\uff0c\u60a8\u5c06\u4e86\u89e3\u6709\u5173 System.IO \u547d\u540d\u7a7a\u95f4\u7684\u6240\u6709\u4fe1\u606f\uff0c\u60a8\u5c06\u5728\u5176\u4e2d\u4e86\u89e3\u5982\u4f55\u5728\u5c1d\u8bd5\u6253\u5f00\u6587\u4ef6\u4e4b\u524d\u4ee5\u7f16\u7a0b\u65b9\u5f0f\u786e\u5b9a\u786c\u76d8\u9a71\u52a8\u5668\u4e0a\u662f\u5426\u5b58\u5728\u6587\u4ef6\uff08\u4ece\u800c\u5b8c\u5168\u907f\u514d\u5f02\u5e38\uff09\u3002\u4f46\u662f\uff0c\u4e3a\u4e86\u7ee7\u7eed\u5173\u6ce8\u5f02\u5e38\u4e3b\u9898\uff0c\u8bf7\u5047\u8bbe\u5df2\u5f15\u53d1\u5f02\u5e38\u3002<\/p>\n
\n{<\/p>\n
\n{
\nFileStream fs = File.Open(@"C:\\carErrors.txt", FileMode.Open);
\n...
\n}
\ncatch (Exception e2)
\n{
\n\/\/This causes a compile error-InnerException is read only
\n\/\/e.InnerException = e2;
\n\/\/ Throw an exception that records the new exception,
\n\/\/ as well as the message of the first exception.
\nthrow new CarIsDeadException( e.CauseOfError, e.ErrorTimeStamp, e.Message, e2); }
\n}<\/p>\n
\n\u8bf7\u6ce8\u610f\uff0c\u5728\u672c\u4f8b\u4e2d\uff0c\u6211\u5df2\u7ecf\u5c06FileNotFoundException\u5bf9\u8c61\u4f5c\u4e3a\u7b2c\u56db\u4e2a\u53c2\u6570\u4f20\u9012\u7ed9CarIsDeadException\u6784\u9020\u51fd\u6570\u3002\u914d\u7f6e\u6b64\u65b0\u5bf9\u8c61\u540e\uff0c\u5c06\u5176\u5c06\u8c03\u7528\u5806\u6808\u629b\u51fa\u7ed9\u4e0b\u4e00\u4e2a\u8c03\u7528\u65b9\uff0c\u5728\u672c\u4f8b\u4e2d\u4e3a\u9876\u7ea7\u8bed\u53e5\u3002<\/p>\n
\n\u9274\u4e8e\u9876\u7ea7\u8bed\u53e5\u540e\u6ca1\u6709\u201c\u4e0b\u4e00\u4e2a\u8c03\u7528\u65b9\u201d\u6765\u6355\u83b7\u5f02\u5e38\uff0c\u60a8\u5c06\u518d\u6b21\u770b\u5230\u4e00\u4e2a\u9519\u8bef\u5bf9\u8bdd\u6846\u3002\u4e0e\u91cd\u65b0\u5f15\u53d1\u5f02\u5e38\u7684\u884c\u4e3a\u975e\u5e38\u76f8\u4f3c\uff0c\u8bb0\u5f55\u5185\u90e8\u5f02\u5e38\u901a\u5e38\u4ec5\u5728\u8c03\u7528\u65b9\u80fd\u591f\u9996\u5148\u4f18\u96c5\u5730\u6355\u83b7\u5f02\u5e38\u65f6\u624d\u6709\u7528\u3002\u5982\u679c\u662f\u8fd9\u79cd\u60c5\u51b5\uff0c\u8c03\u7528\u65b9\u7684 catch \u903b\u8f91\u53ef\u4ee5\u4f7f\u7528 InnerException \u5c5e\u6027\u63d0\u53d6\u5185\u90e8\u5f02\u5e38\u5bf9\u8c61\u7684\u8be6\u7ec6\u4fe1\u606f\u3002<\/p>\nThe finally Block<\/h2>\n
\nA try\/catch scope may also define an optional finally block. The purpose of a finally block is to ensure that a set of code statements will always execute, exception (of any type) or not. To illustrate, assume you want to always power down the car\u2019s radio before exiting the program, regardless of any handled exception.
\ntry\/catch \u8303\u56f4\u4e5f\u53ef\u4ee5\u5b9a\u4e49\u4e00\u4e2a\u53ef\u9009\u7684 finally \u5757\u3002finally \u5757\u7684\u76ee\u7684\u662f\u786e\u4fdd\u4e00\u7ec4\u4ee3\u7801\u8bed\u53e5\u59cb\u7ec8\u6267\u884c\uff0c\u65e0\u8bba\u662f\u5426\u5f02\u5e38\uff08\u4efb\u4f55\u7c7b\u578b\u7684\uff09\u3002\u4e3a\u4e86\u8bf4\u660e\u8fd9\u4e00\u70b9\uff0c\u5047\u8bbe\u60a8\u5e0c\u671b\u59cb\u7ec8\u5728\u9000\u51fa\u7a0b\u5e8f\u4e4b\u524d\u5173\u95ed\u6c7d\u8f66\u7684\u6536\u97f3\u673a\uff0c\u800c\u4e0d\u7ba1\u4efb\u4f55\u5904\u7406\u7684\u5f02\u5e38\u3002<\/p>\n
\nmyCar.CrankTunes(true); try
\n{
\n\/\/ Speed up car logic.
\n}
\ncatch(CarIsDeadException e)
\n{
\n\/\/ Process CarIsDeadException.
\n}
\ncatch(ArgumentOutOfRangeException e)
\n{
\n\/\/ Process ArgumentOutOfRangeException.
\n}
\ncatch(Exception e)
\n{
\n\/\/ Process any other Exception.
\n}<\/p>\n
\n{
\n\/\/ This will always occur. Exception or not. myCar.CrankTunes(false);
\n}
\nConsole.ReadLine();<\/p>\n
\n\u5982\u679c\u672a\u5305\u542b finally \u5757\uff0c\u5219\u5728\u9047\u5230\u5f02\u5e38\u65f6\u4e0d\u4f1a\u5173\u95ed\u65e0\u7ebf\u7535\uff08\u53ef\u80fd\u4f1a\u4e5f\u53ef\u80fd\u6ca1\u6709\u95ee\u9898\uff09\u3002\u5728\u66f4\u771f\u5b9e\u7684\u573a\u666f\u4e2d\uff0c\u5f53\u60a8\u9700\u8981\u91ca\u653e\u5bf9\u8c61\u3001\u5173\u95ed\u6587\u4ef6\u6216\u4ece\u6570\u636e\u5e93\u5206\u79bb\uff08\u6216\u5176\u4ed6\u4efb\u4f55\u5185\u5bb9\uff09\u65f6\uff0cfinally \u5757\u53ef\u786e\u4fdd\u6b63\u786e\u6e05\u7406\u7684\u4f4d\u7f6e\u3002<\/p>\nException Filters<\/h2>\n
\nC# 6 \u5f15\u5165\u4e86\u4e00\u4e2a\u65b0\u5b50\u53e5\uff0c\u53ef\u4ee5\u901a\u8fc7 when \u5173\u952e\u5b57\u5c06\u5176\u653e\u7f6e\u5728 catch \u4f5c\u7528\u57df\u4e2d\u3002\u6dfb\u52a0\u6b64\u5b50\u53e5\u65f6\uff0c\u80fd\u591f\u786e\u4fdd\u4ec5\u5f53\u4ee3\u7801\u4e2d\u7684\u67d0\u4e9b\u6761\u4ef6\u6210\u7acb\u65f6\uff0c\u624d\u6267\u884c catch \u5757\u4e2d\u7684\u8bed\u53e5\u3002\u6b64\u8868\u8fbe\u5f0f\u7684\u8ba1\u7b97\u7ed3\u679c\u5fc5\u987b\u4e3a\u5e03\u5c14\u503c\uff08\u771f\u6216\u5047\uff09\uff0c\u53ef\u4ee5\u901a\u8fc7\u5728 when \u5b9a\u4e49\u672c\u8eab\u4e2d\u4f7f\u7528\u7b80\u5355\u7684\u4ee3\u7801\u8bed\u53e5\u6216\u5728\u4ee3\u7801\u4e2d\u8c03\u7528\u5176\u4ed6\u65b9\u6cd5\u6765\u83b7\u53d6\u3002\u7b80\u800c\u8a00\u4e4b\uff0c\u6b64\u65b9\u6cd5\u5141\u8bb8\u60a8\u5411\u5f02\u5e38\u903b\u8f91\u6dfb\u52a0\u201c\u7b5b\u9009\u5668\u201d\u3002<\/p>\n
\n\u8bf7\u8003\u8651\u4ee5\u4e0b\u4fee\u6539\u540e\u7684\u5f02\u5e38\u903b\u8f91\u3002\u6211\u5728 CarIsDeadException \u5904\u7406\u7a0b\u5e8f\u4e2d\u6dfb\u52a0\u4e86\u4e00\u4e2a when \u5b50\u53e5\uff0c\u4ee5\u786e\u4fdd catch \u5757\u6c38\u8fdc\u4e0d\u4f1a\u5728\u661f\u671f\u4e94\u6267\u884c\uff08\u4e00\u4e2a\u4eba\u4e3a\u7684\u4f8b\u5b50\uff0c\u4f46\u8c01\u5e0c\u671b\u4ed6\u4eec\u7684\u6c7d\u8f66\u5728\u5468\u672b\u4e4b\u524d\u53d1\u751f\u6545\u969c\uff1f\u8bf7\u6ce8\u610f\uff0cwhen \u5b50\u53e5\u4e2d\u7684\u5355\u4e2a\u5e03\u5c14\u8bed\u53e5\u5fc5\u987b\u62ec\u5728\u62ec\u53f7\u4e2d\u3002<\/p>\n
\n{
\n\/\/ This new line will only print if the when clause evaluates to true.
\n\/\/ \u4ec5\u5f53 when \u5b50\u53e5\u7684\u8ba1\u7b97\u7ed3\u679c\u4e3a true \u65f6\uff0c\u624d\u4f1a\u6253\u5370\u6b64\u65b0\u884c\u3002
\nConsole.WriteLine("Catching car is dead!");<\/p>\n
\n}<\/p>\n
\n\u867d\u7136\u6b64\u793a\u4f8b\u975e\u5e38\u4eba\u4e3a\uff0c\u4f46\u4f7f\u7528\u5f02\u5e38\u7b5b\u9009\u5668\u7684\u66f4\u5b9e\u9645\u7528\u9014\u662f\u6355\u83b7 SystemException\u3002\u4f8b\u5982\uff0c\u5047\u8bbe\u60a8\u7684\u4ee3\u7801\u6b63\u5728\u5c06\u6570\u636e\u4fdd\u5b58\u5230\u6570\u636e\u5e93\uff0c\u5219\u4f1a\u5f15\u53d1\u5e38\u89c4\u5f02\u5e38\u3002\u901a\u8fc7\u68c0\u67e5\u6d88\u606f\u548c\u5f02\u5e38\u6570\u636e\uff0c\u53ef\u4ee5\u6839\u636e\u5bfc\u81f4\u5f02\u5e38\u7684\u539f\u56e0\u521b\u5efa\u7279\u5b9a\u7684\u5904\u7406\u7a0b\u5e8f\u3002<\/p>\n
\n\u4f7f\u7528 Visual Studio \u8c03\u8bd5\u672a\u7ecf\u5904\u7406\u7684\u5f02\u5e38<\/p>\n
\nVisual Studio \u63d0\u4f9b\u4e86\u8bb8\u591a\u5de5\u5177\u6765\u5e2e\u52a9\u4f60\u8c03\u8bd5\u672a\u7ecf\u5904\u7406\u7684\u5f02\u5e38\u3002\u5047\u8bbe\u60a8\u5df2\u5c06 Car \u5bf9\u8c61\u7684\u901f\u5ea6\u63d0\u9ad8\u5230\u8d85\u8fc7\u6700\u5927\u503c\uff0c\u4f46\u8fd9\u6b21\u6ca1\u6709\u8d39\u5fc3\u5c06\u60a8\u7684\u8c03\u7528\u5305\u88c5\u5728 try \u5757\u4e2d\u3002
\nCar myCar = new Car("Rusty", 90); myCar.Accelerate(100);<\/p>\n
\n\u5982\u679c\u5728 Visual Studio \u4e2d\u542f\u52a8\u8c03\u8bd5\u4f1a\u8bdd\uff08\u4f7f\u7528\u201c\u8c03\u8bd5\u201d\u27a4\u201c\u542f\u52a8\u8c03\u8bd5\u201d\u83dc\u5355\u9009\u9879\uff09\uff0c\u5219\u5728\u5f15\u53d1\u672a\u6355\u83b7\u7684\u5f02\u5e38\u65f6\uff0cVisual Studio \u4f1a\u81ea\u52a8\u4e2d\u65ad\u3002\u66f4\u597d\u7684\u662f\uff0c\u60a8\u5c06\u770b\u5230\u4e00\u4e2a\u7a97\u53e3\uff08\u8bf7\u53c2\u9605\u56fe 7-1\uff09\uff0c\u5176\u4e2d\u663e\u793a\u4e86 Message \u5c5e\u6027\u7684\u503c\u3002<\/p>\n![\"Alt](\"\/images\/0701.jpg\")
<\/p>\n
\n\u56fe 7-1\u3002 \u4f7f\u7528 Visual Studio \u8c03\u8bd5\u672a\u7ecf\u5904\u7406\u7684\u81ea\u5b9a\u4e49\u5f02\u5e38<\/p>\n
\n\u6ce8\u610f \u5982\u679c\u65e0\u6cd5\u5904\u7406 .neT \u57fa\u7c7b\u5e93\u4e2d\u7684\u65b9\u6cd5\u5f15\u53d1\u7684\u5f02\u5e38\uff0cVisual Studio \u8c03\u8bd5\u5668\u5c06\u5728\u8c03\u7528\u8fdd\u89c4\u65b9\u6cd5\u7684\u8bed\u53e5\u5904\u4e2d\u65ad\u3002<\/p>\n
\n\u5982\u679c\u5355\u51fb\u201c\u67e5\u770b\u8be6\u7ec6\u4fe1\u606f\u201d\u94fe\u63a5\uff0c\u5c06\u627e\u5230\u6709\u5173\u5bf9\u8c61\u72b6\u6001\u7684\u8be6\u7ec6\u4fe1\u606f\uff08\u8bf7\u53c2\u9605\u56fe 7-2\uff09\u3002<\/p>\n![\"Alt](\"\/images\/0702.jpg\")
<\/p>\n
\n\u56fe 7-2\u3002 \u67e5\u770b\u5f02\u5e38\u8be6\u7ec6\u4fe1\u606f<\/p>\nSummary<\/h2>\n
\n\u5728\u672c\u7ae0\u4e2d\uff0c\u60a8\u7814\u7a76\u4e86\u7ed3\u6784\u5316\u5f02\u5e38\u5904\u7406\u7684\u4f5c\u7528\u3002\u5f53\u65b9\u6cd5\u9700\u8981\u5411\u8c03\u7528\u65b9\u53d1\u9001\u9519\u8bef\u5bf9\u8c61\u65f6\uff0c\u5b83\u5c06\u901a\u8fc7 throw\uff08\uff09 \u5206\u914d\u3001\u914d\u7f6e\u548c\u629b\u51fa\u7279\u5b9a\u7684 System.Exception \u6d3e\u751f\u7c7b\u578b\u3002\u8c03\u7528\u65b9\u80fd\u591f\u4f7f\u7528 C# catch \u5173\u952e\u5b57\u548c\u53ef\u9009\u7684 finally \u4f5c\u7528\u57df\u5904\u7406\u4efb\u4f55\u53ef\u80fd\u7684\u4f20\u5165\u5f02\u5e38\u3002\u81ea C# 6.0 \u8d77\uff0c\u6dfb\u52a0\u4e86\u4f7f\u7528\u53ef\u9009 when \u5173\u952e\u5b57\u521b\u5efa\u5f02\u5e38\u7b5b\u9009\u5668\u7684\u529f\u80fd\uff0c\u5e76\u4e14 C# 7 \u6269\u5c55\u4e86\u53ef\u4ee5\u5f15\u53d1\u5f02\u5e38\u7684\u4f4d\u7f6e\u3002<\/p>\n
\napplication. In contrast, error objects deriving from System.SystemException represent critical (and fatal)
\nerrors thrown by the .NET runtime. Last but not least, this chapter illustrated various tools within Visual Studio that can be used to create custom exceptions (according to .NET best practices) as well as debug exceptions.
\n\u5728\u521b\u5efa\u81ea\u5df1\u7684\u81ea\u5b9a\u4e49\u5f02\u5e38\u65f6\uff0c\u6700\u7ec8\u4f1a\u521b\u5efa\u4e00\u4e2a\u6d3e\u751f\u81ea System.ApplicationException \u7684\u7c7b\u7c7b\u578b\uff0c\u8be5\u7c7b\u7c7b\u578b\u8868\u793a\u4ece\u5f53\u524d\u6267\u884c\u7684\u5e94\u7528\u3002\u76f8\u53cd\uff0c\u6d3e\u751f\u81ea System.SystemException \u7684\u9519\u8bef\u5bf9\u8c61\u8868\u793a\u4e25\u91cd\uff08\u548c\u4e25\u91cd\uff09.NET \u8fd0\u884c\u65f6\u5f15\u53d1\u7684\u9519\u8bef\u3002\u6700\u540e\u4f46\u5e76\u975e\u6700\u4e0d\u91cd\u8981\u7684\u4e00\u70b9\u662f\uff0c\u672c\u7ae0\u6f14\u793a\u4e86Visual Studio\u4e2d\u7684\u5404\u79cd\u5de5\u5177\uff0c\u8fd9\u4e9b\u5de5\u5177\u53ef\u7528\u4e8e\u521b\u5efa\u81ea\u5b9a\u4e49\u5f02\u5e38\uff08\u6839\u636e.NET\u6700\u4f73\u5b9e\u8df5\uff09\u4ee5\u53ca\u8c03\u8bd5\u5f02\u5e38\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"