(C#) Tasks 中的异常处理（Exception Handling.）
2024-08-25 10:29:39
多线程编程中要注意对线程异常的处理。首先写个例子。
一个线程用于显示信息(Show Messages)。主线程用于做其他工作(Do Works)。
using (Task taskShowMessages = new Task(ShowMessages))
{
try
{
taskShowMessages.Start();
DoWorks();
}
catch (DoWorkException ex)
{
Console.WriteLine("Error:{0}", ex.Message);
}
catch(Exception ex)
{
Console.WriteLine("Error:{0}", ex.Message);
}
}
public static void ShowMessages()
{
int i = ;
while (true)
{
Console.WriteLine("{0} - Message_{1}", DateTime.Now.ToString(), i++);
Thread.Sleep(); if ( i == 3)
{
throw new ShowMessageException(string.Format("User defined error occured during showing message_{0}!", i));
//throw new Exception(string.Format("Unhandled exception occured during showing message_{0}!", i));
}
}
} public static void DoWorks()
{
int i = ;
while (true)
{
Console.WriteLine("{0} - DoWork_{1}", DateTime.Now.ToString(), i++);
Thread.Sleep(); if (i == )
{
throw new DoWorkException(string.Format("User defined error occured during doing work_{0}!", i));
//throw new Exception(string.Format("Unhandled exception occured during doing work{0}!", i));
}
}
} public class ShowMessageException : Exception
{
public ShowMessageException(String message)
: base(message)
{
}
} public class DoWorkException : Exception
{
public DoWorkException(String message)
: base(message)
{
}
}
输出：
// :: PM - DoWork_0
// :: PM - Message_0
// :: PM - Message_1
// :: PM - DoWork_1
// :: PM - Message_2
// :: PM - DoWork_2
// :: PM - DoWork_3
Error:User defined error occured during doing work_4!
可以看出来，Show Message 3 时发生一个异常，但是本程序无视它并继续DoWorks。知道DoWorks发生异常抛出。
在VS的debug环境下可以看到这个异常的发生：
A first chance exception of type 'ConsoleApplication2.Program.ShowMessageException' occurred in ConsoleApplication2.exe
A first chance exception of type 'ConsoleApplication2.Program.DoWorkException' occurred in ConsoleApplication2.exe
如果想正确的处理ShowMessage线程的异常，必须对其 Wait（）方法进行处理。
using (Task taskShowMessages = new Task(ShowMessages))
{
try
{
taskShowMessages.Start();
DoWorks();
}
catch (DoWorkException ex)
{
Console.WriteLine("Error is handled:{0}", ex.Message);
}
finally
{
try
{
taskShowMessages.Wait();
}
catch(AggregateException ae)
{
ae.Handle((x) =>
{
if (x is ShowMessageException)
{
Console.WriteLine("Error is handled:{0}", x.Message);
return true;
}
else
{
return false;
}
});
}
}
}
输出：
// :: PM - DoWork_0
// :: PM - Message_0
// :: PM - Message_1
// :: PM - DoWork_1
// :: PM - Message_2
// :: PM - DoWork_2
// :: PM - DoWork_3
Error is handled:User defined error occured during doing work_4!
Error is handled:User defined error occured during showing message_3!
那么现在如果其中一个线程出现异常的话，我们就希望抛出异常，结束程序，怎么做?
答案就是使用：
CancellationTokenSource
static CancellationTokenSource cancellationtoken = new CancellationTokenSource();
static void Main(string[] args)
{ using (Task taskShowMessages = new Task(ShowMessages, cancellationtoken.Token))
{
try
{
taskShowMessages.Start();
DoWorks();
}
catch (DoWorkException ex)
{
Console.WriteLine("Error is handled:{0}", ex.Message);
}
finally
{
cancellationtoken.Cancel(); try
{
taskShowMessages.Wait();
}
catch (AggregateException ae)
{
ae.Handle((x) =>
{
if (x is ShowMessageException)
{
Console.WriteLine("Error is handled:{0}", x.Message);
return true;
}
else
{
return false;
}
});
}
}
}
} public static void ShowMessages()
{
int i = ;
while (!cancellationtoken.IsCancellationRequested)
{
Console.WriteLine("{0} - Message_{1}", DateTime.Now.ToString(), i++);
Thread.Sleep(); if ( i == )
{
//throw new ShowMessageException(string.Format("User defined error occured during showing message_{0}!", i));
//throw new Exception(string.Format("Unhandled exception occured during showing message_{0}!", i));
//break;
}
}
}
输出：
// :: PM - DoWork_0
// :: PM - Message_0
// :: PM - Message_1
// :: PM - DoWork_1
// :: PM - Message_2
// :: PM - Message_3
// :: PM - DoWork_2
// :: PM - Message_4
// :: PM - Message_5
// :: PM - DoWork_3
// :: PM - Message_6
// :: PM - Message_7
Error is handled:User defined error occured during doing work_4!
参考：
https://msdn.microsoft.com/en-us/library/dd997415(v=vs.110).aspx
https://msdn.microsoft.com/en-us/library/dd537614(v=vs.110).aspx
最新文章
- Backbone.js学习之二
- hyperv 创建第二代虚拟机
- Spring IoC容器的设计—1—主线
- 类库探源——System.ValueType
- [学习笔记]设计模式之Decorator
- el和jstl
- phpcms在自定义模块中的自定义标签分页
- EOCS框架概述和剖析
- Java概念、语法和变量基础整理
- python 对象转字典
- Unity 发送游戏画面到 Winform
- 解决Hive与Elasticsearch共有库 guava 冲突 NoSuchMethodError
- Animation和Animator 的区别
- Java对象池
- 使用 http 请求方式获取 eureka server的服务信息
- 聊一聊PV和并发、以及计算web服务器的数量的方法
- Linux—rm命令
- centos 正则，grep，egrep，流式编辑器 sed，awk -F 多个分隔符 通配符 特殊符号. * + ? 总结 问加星 cat -n nl 输出文件内容并加上行号 alias放~/.bash_profile 2015-4-10 第十三节课
- Python安装安装.whl包（安装pylint）
- AndroidStudio项目提交（更新）到github最具体步骤