C#中多线程应用

参考地址：http://www.dingos.cn/index.php?topic=805.0

介绍

线程是轻量级的进程。使用线程能提供应用系统的效率。为了使用多线程需要引入System命名空间中的Threading命名空间。System.Threading命名空间包含需要使用多线程的地方。现在让我们来看第一个程序。

示例分析

示例1（Program01.cs）

using System;

using System.Threading;

 

public class MyThread {

    public staticvoid Thread1() {

        for (inti = 0; i < 10; i++) {

           Console.WriteLine("Thread1 {0}", i);

        }

    }

    public staticvoid Thread2() {

        for (inti = 0; i < 10; i++) {

           Console.WriteLine("Thread2 {0}", i);

        }

    }

}

public class MyClass {

    public staticvoid Main() {

       Console.WriteLine("Before start thread");

        Threadtid1 = new Thread(new ThreadStart(MyThread.Thread1));

        Threadtid2 = new Thread(new ThreadStart(MyThread.Thread2));

       tid1.Start();

       tid2.Start();

    }

}

开始探索整个程序。

这个程序有一个MyThread类包括两个静态方法Thread1和Thread2。为了创建线程需要创建Thread类对象。Thread类的构造方法是ThreadStart的引用。这个构造方法可能会发出两种类型的异常；当参数是一个空引用时引发ArgumentNullException异常或当程序不允许创建线程的SecurityException异常。

Thread类的参数是ThreadStart的引用。当线程开始时执行ThreadStart指向的方法。ThreadStart的参数名是函数名，作为线程的函数。Thread1是一个静态方法可以使用类名来访问不需要要创建类的对象。线程开始执行Thread类的Start()方法。下面是程序的输出：

Before start thread
Thread1 0
Thread1 1
Thread1 2
Thread1 3
Thread1 4
Thread1 5
Thread1 6
Thread1 7
Thread1 8
Thread1 9
Thread2 0
Thread2 1
Thread2 2
Thread2 3
Thread2 4
Thread2 5
Thread2 6
Thread2 7
Thread2 8
Thread2 9

线程的方法可以不是静态方法。在下面的例子中使用非静态方法需要创建类的对象。

示例2（Program02.cs）

using System;

using System.Threading;

 

public class MyThread {

    public voidThread1() {

        for (inti = 0; i < 10; i++) {

           Console.WriteLine("Thread1 {0}", i);

        }

    }

 

    public voidThread2() {

        for (inti = 0; i < 10; i++) {

           Console.WriteLine("Thread2 {0}", i);

        }

    }

}

 

public class MyClass {

    public staticvoid Main() {

       Console.WriteLine("Before start thread");

 

        MyThreadthr = new MyThread();

 

        Threadtid1 = new Thread(new ThreadStart(thr.Thread1));

        Threadtid2 = new Thread(new ThreadStart(thr.Thread2));

 

       tid1.Start();

       tid2.Start();

    }

}

这个程序的输出和上一个的输出相同。

不需要为两个线程创建两个方法。可以使用一个方法为两个线程类创建两个线程。看下面的程序。

示例3（Program03.cs）

using System;

using System.Threading;

 

public class MyThread {

    public voidThread1() {

        for (inti = 0; i < 10; i++) {

            Console.WriteLine("Helloworld {0}", i);

        }

    }

}

 

public class MyClass {

    public staticvoid Main() {

       Console.WriteLine("Before start thread");

 

        MyThreadthr1 = new MyThread();

        MyThreadthr2 = new MyThread();

 

        Threadtid1 = new Thread(new ThreadStart(thr1.Thread1));

        Threadtid2 = new Thread(new ThreadStart(thr2.Thread1));

 

       tid1.Start();

       tid2.Start();

    }

}

这里创建了两个MyThread对象执行两个线程。

在构造方法传递参数时也不需要创建ThreadStart对象。可以创建ThreadStart对象并将它传递给Thread参数。看下面的程序。

示例4（Program04.cs）

using System;

using System.Threading;

 

public class MyThread {

    public voidThread1() {

        for (inti = 0; i < 10; i++) {

           Console.WriteLine("Hello world {0}", i);

        }

    }

}

 

public class MyClass {

    public staticvoid Main() {

       Console.WriteLine("Before start thread");

 

        MyThreadthr1 = new MyThread();

        MyThreadthr2 = new MyThread();

 

       ThreadStart tStart1 = new ThreadStart(thr1.Thread1);

       ThreadStart tStart2 = new ThreadStart(thr2.Thread1);

 

        Threadtid1 = new Thread(tStart1);

        Threadtid2 = new Thread(tStart2);

 

       tid1.Start();

       tid2.Start();

    }

}

这个程序也有相同的输出。

Sleep方法在指定的时间范围内挂起线程。Sleep是静态方法使用时不需要创建Thread线程。有两个重载的Sleep()方法，一个是指定时间的毫秒数，另一个是TimeSpan结构的实例。

示例5（Program05.cs）

using System;

using System.Threading;

 

public class MyThread {

    public voidThread1() {

        for (inti = 0; i < 10; i++) {

           Console.WriteLine("Hello world " + i);

           Thread.Sleep(1);

        }

    }

}

 

public class MyClass {

    public staticvoid Main() {

       Console.WriteLine("Before start thread");

 

        MyThreadthr1 = new MyThread();

        MyThreadthr2 = new MyThread();

 

        Threadtid1 = new Thread(new ThreadStart(thr1.Thread1) );

        Threadtid2 = new Thread(new ThreadStart(thr2.Thread1) );

 

       tid1.Start();

       tid2.Start();

    }

}

这个线程休眠1秒并给第二个线程一个机会执行。下面是输出结果：

Before start thread
Hello world 0
Hello world 0
Hello world 1
Hello world 1
Hello world 2
Hello world 2
Hello world 3
Hello world 3
Hello world 4
Hello world 4
Hello world 5
Hello world 5
Hello world 6
Hello world 6
Hello world 7
Hello world 7
Hello world 8
Hello world 8
Hello world 9
Hello world 9

看似这两个线程是并行执行的。下面程序将显示重载的Sleeep方法。

示例6（Program06.cs）

using System;

using System.Threading;

 

public class MyThread {

    public voidThread1() {

        for (inti = 0; i < 10; i++) {

            intiHour = 0;

            intiMin = 0;

            intiSec = 1;

 

           Console.WriteLine("Hello world " + i);

           Thread.Sleep(new TimeSpan(iHour, iMin, iSec) );

        }

    }

}

 

public class MyClass {

    public staticvoid Main() {

       Console.WriteLine("Before start thread");

 

        MyThreadthr1 = new MyThread();

        MyThreadthr2 = new MyThread();

 

        Threadtid1 = new Thread(new ThreadStart(thr1.Thread1) );

        Threadtid2 = new Thread(new ThreadStart(thr2.Thread1) );

 

       tid1.Start();

       tid2.Start();

    }

}

TimeSpan结构有四个重载的构造方法。第一个是参数为长整型的指定特殊值，第二个有3个整型参数分别表示时、分、秒，第3个有4个整型参数分别表示日、时、分、秒，第4个构造方法有5 个参数表示日、时、分、秒和毫秒。这个程序和上面的程序打印一秒钟打印一次新值外其他的相同。

Sleep方法抛出3中类型的异常：当时间值小于0时将引发ArgumentException异常，当休眠线程中断时引发ThreadInterruptedException异常，当不适当的时候调用方法将引发SecurityException异常。

下面程序显示执行情况下Sleep()方法是负面的。

示例7（Program07.cs）

using System;

using System.Threading;

 

public class MyThread {

    public voidThread1() {

        for (inti = 0; i < 10; i++) {

            intiHour = 0;

            intiMin = 0;

            intiSec = -1;

 

            try {

               Console.WriteLine("Hello world " + i);

               Thread.Sleep(new TimeSpan(iHour, iMin, iSec) );

            }catch (ArgumentException ae) {

               Console.WriteLine(ae.Message );

            }

        }

    }

}

 

public class MyClass {

    public staticvoid Main() {

       Console.WriteLine("Before start thread");

 

        MyThreadthr1 = new MyThread();

        MyThreadthr2 = new MyThread();

 

        Threadtid1 = new Thread(new ThreadStart(thr1.Thread1) );

        Threadtid2 = new Thread(new ThreadStart(thr2.Thread1) );

 

       tid1.Start();

       tid2.Start();

    }

}

Message是ArgumentException类的一个属性用来描述异常信息。在这个程序中会给出如下错误信息。

Parameter Name: Argument must be greater than 0 and less than2^31 - 1milliseconds.

也可以通过Thead类的Name属性通过线程的名称来访问线程。

示例8（Program08.cs）

using System;

using System.Threading;

 

public class MyThread {

    public voidThread1() {

        for (inti = 0; i < 10; i++) {

           Thread thr = Thread.CurrentThread;

           Console.WriteLine(thr.Name + "=" + i);

           Thread.Sleep(1);

        }

    }

}

 

public class MyClass {

    public staticvoid Main() {

        Console.WriteLine("Beforestart thread");

 

        MyThreadthr1 = new MyThread();

        MyThreadthr2 = new MyThread();

 

        Threadtid1 = new Thread(new ThreadStart(thr1.Thread1) );

        Threadtid2 = new Thread(new ThreadStart(thr2.Thread1) );

 

        tid1.Name= "Thread 1";

        tid2.Name= "Thread 2";

 

       tid1.Start();

       tid2.Start();

    }

}

为了防止应用程序崩溃可以在可能发生异常的地方捕获异常。可能在Sleep方法中抛出异常，可以用try来捕获所有的异常。

示例9（Program09.cs）

using System;

using System.Threading;

using System.Security;

 

public class MyThread {

    public voidThread1() {

        for (inti = 0; i < 10; i++) {

           Thread thr = Thread.CurrentThread;

           Console.WriteLine(thr.Name + "=" + i);

 

            try {

               Thread.Sleep(1);

            }catch (ArgumentException ae) {

               Console.WriteLine(ae.ToString() );

            }catch (ThreadInterruptedException tie) {

               Console.WriteLine(tie.ToString() );

            }catch (SecurityException se) {

                Console.WriteLine(se.ToString() );

            }

        }

    }

}

 

public class MyClass {

    public staticvoid Main() {

       Console.WriteLine("Before start thread");

 

        MyThreadthr1 = new MyThread();

        MyThreadthr2 = new MyThread();

 

        Threadtid1 = new Thread(new ThreadStart(thr1.Thread1) );

        Threadtid2 = new Thread(new ThreadStart(thr2.Thread1) );

 

        tid1.Name= "Thread 1";

        tid2.Name= "Thread 2";

 

       tid1.Start();

       tid2.Start();

    }

}

这个程序捕获了三个异常。看这段代码的第一行。多用了一个命名空间：System.Security。SecurityException异常类定义在这个命名空间。

在创建线程实例的方法中为线程命名。可以通过CurrentThread获得线程的名称。CurrentThread是线程类的静态方法。当调用者不适合安全访问这个属性抛出的一个异常：SecurityException。

程序的运行结果：

Before start thread
Thread 1=0
Thread 2=0
Thread 1=1
Thread 2=1
Thread 1=2
Thread 2=2
Thread 1=3
Thread 2=3
Thread 1=4
Thread 2=4
Thread 1=5
Thread 2=5
Thread 1=6
Thread 2=6
Thread 1=7
Thread 2=7
Thread 1=8
Thread 2=8
Thread 1=9
Thread 2=9

可以使用Abort()终止线程。Abort有两个重载方法。第一个是执行没有参数的方法，第二个是带有Object参数的方法。这个方法抛出ThreadAbortException异常没有被捕获。看下面的程序：

示例10（Program10.cs）

using System;

using System.Threading;

using System.Security;

 

public class MyThread {

    public voidThread1() {

        for (inti = 0; i < 10; i++) {

           Thread thr = Thread.CurrentThread;

           Console.WriteLine(thr.Name + "=" + i);

 

            try {

               Thread.Sleep(1);

            }catch (ArgumentException ae) {

               Console.WriteLine(ae.ToString() );

            }catch (ThreadInterruptedException tie) {

                Console.WriteLine(tie.ToString());

            }catch (SecurityException se) {

               Console.WriteLine(se.ToString() );

            }

        }

    }

}

 

public class MyClass {

    public staticvoid Main() {

       Console.WriteLine("Before start thread");

 

        MyThreadthr1 = new MyThread();

        MyThreadthr2 = new MyThread();

 

        Threadtid1 = new Thread(new ThreadStart(thr1.Thread1) );

        Threadtid2 = new Thread(new ThreadStart(thr2.Thread1) );

 

        tid1.Name= "Thread 1";

        tid2.Name= "Thread 2";

 

       tid1.Start();

       tid2.Start();

 

        try {

           tid1.Abort();

           tid2.Abort();

        } catch(ThreadAbortException tae) {

           Console.WriteLine(tae.ToString() );

        }

       Console.WriteLine("End of Main");

    }

}

程序输出：

Before start Thread
End of Main

这个输出结果很明显的表面线程没有执行。一个线程终止后就不能在开始。看下面的程序。

示例11（Program11.cs）

using System;

using System.Threading;

 

public class MyThread {

    public voidThread1() {

        for (inti = 0; i < 10; i++) {

           Thread thr = Thread.CurrentThread;

           Console.WriteLine(thr.Name + "=" + i);

           Thread.Sleep(1);

        }

    }

}

 

public class MyClass {

    public staticvoid Main() {

       Console.WriteLine("Before start thread");

 

        MyThreadthr1 = new MyThread();

        MyThreadthr2 = new MyThread();

 

        Threadtid1 = new Thread(new ThreadStart(thr1.Thread1) );

        Threadtid2 = new Thread(new ThreadStart(thr2.Thread1) );

 

        tid1.Name= "Thread 1";

        tid2.Name= "Thread 2";

 

       tid1.Start();

       tid2.Start();

 

       tid1.Abort();

       tid2.Abort();

 

       Console.WriteLine("After Abort");

 

       tid1.Start();

       tid2.Start();

 

       Console.WriteLine("End of Main");

    }

}

这个程序抛出一个System.Threading.ThreadStateException异常。现在使用异常捕获后关闭程序而不是用异常终止。

示例12（Program12.cs）

using System;

using System.Threading;

 

public class MyThread {

    public voidThread1() {

        for (int i = 0; i < 10; i++) {

           Thread thr = Thread.CurrentThread;

           Console.WriteLine(thr.Name + "=" + i);

           Thread.Sleep(1);

        }

    }

}

 

public class MyClass {

    public staticvoid Main() {

       Console.WriteLine("Before start thread");

 

        MyThreadthr1 = new MyThread();

        MyThreadthr2 = new MyThread();

 

        Threadtid1 = new Thread(new ThreadStart(thr1.Thread1) );

        Threadtid2 = new Thread(new ThreadStart(thr2.Thread1) );

 

        tid1.Name= "Thread 1";

        tid2.Name= "Thread 2";

 

        try {

           tid1.Start();

           tid2.Start();

        } catch(ThreadStateException te) {

           Console.WriteLine(te.ToString() );

        }

 

       tid1.Abort();

       tid2.Abort();

 

        try {

           tid1.Start();

           tid2.Start();

        } catch(ThreadStateException te) {

           Console.WriteLine(te.ToString() );

        }

       Console.WriteLine("End of Main");

    }

}

这里捕获ThreadStatException异常并用这个类的ToString方法。ToString方法返回一个异常的全缀名，和可能的错误信息，异常内部名和堆跟踪信息。

可以用Join方法来等待终端的线程。这个方法有三个重载方法。第一个没有参数等待仍然逝去的线程，第二个是带有一个int参数在期待的时间内等待逝去的线程，第三个是带TimeSpan结果的引用，看下面的程序。

示例13（Program13.cs）

using System;

using System.Threading;

 

public class MyThread {

    public voidThread1() {

        for (inti = 0; i < 10; i++) {

           Thread thr = Thread.CurrentThread;

           Console.WriteLine(thr.Name + "=" + i);

           Thread.Sleep(1);

        }

    }

}

 

public class MyClass {

    public staticvoid Main() {

       Console.WriteLine("Before start thread");

 

        MyThreadthr1 = new MyThread();

        MyThreadthr2 = new MyThread();

 

        Threadtid1 = new Thread(new ThreadStart(thr1.Thread1) );

        Threadtid2 = new Thread(new ThreadStart(thr2.Thread1) );

 

        tid1.Name= "Thread 1";

        tid2.Name= "Thread 2";

 

        try {

           tid1.Start();

           tid2.Start();

        } catch(ThreadStateException te) {

           Console.WriteLine(te.ToString() );

        }

 

       tid1.Join();

       tid2.Join(new TimeSpan(0, 0, 1) );

 

       Console.WriteLine("End of Main");

    }

}

程序等等第一个线程知道他完成为止第二个线程等待1秒。

线程执行有两种方法：后台和前台。当应用程序终止时后台线程完成，另一个前台线程不等的应用程序终止。设置线程执行使用IsBackground属性。下面程序显示了这个用法。

示例14（Program14.cs）

using System;

using System.Threading;

 

public class MyThread {

    public voidThread1() {

        for (inti = 0; i < 10; i++) {

           Thread thr = Thread.CurrentThread;

           Console.WriteLine(thr.Name + "=" + i);

           Thread.Sleep(1);

        }

    }

}

 

public class MyClass {

    public staticvoid Main() {

       Console.WriteLine("Before start thread");

 

        MyThreadthr1 = new MyThread();

        MyThreadthr2 = new MyThread();

 

        Threadtid1 = new Thread(new ThreadStart(thr1.Thread1) );

        Threadtid2 = new Thread(new ThreadStart(thr2.Thread1) );

 

        tid1.Name= "Thread 1";

        tid2.Name= "Thread 2";

 

       tid1.IsBackground = true;

       tid2.IsBackground = true;

 

        try {

           tid1.Start();

           tid2.Start();

        } catch(ThreadStateException te) {

           Console.WriteLine(te.ToString() );

        }

 

       Thread.Sleep(10);

 

       Console.WriteLine("End of Main");

    }

}

程序输出：

Before start thread
Thread 1=0
Thread 2=0
Thread 1=1
Thread 2=1
End of Main

输出显示当应用程序终止时两个背景线程也都终止。

也可以为线程设置优先权。可以使用Thread类的ThreadPriority属性来设置线程的优先级。下面程序显示使用线程的属性设置有效级。

示例15（Program15.cs）

using System;

using System.Threading;

 

public class MyThread {

    public voidThread1() {

        for (inti = 0; i < 10; i++) {

           Thread thr = Thread.CurrentThread;

           Console.WriteLine(thr.Name + "=" + i);

           Thread.Sleep(1);

        }

    }

}

 

public class MyClass {

    public staticvoid Main() {

       Console.WriteLine("Before start thread");

 

        MyThreadthr1 = new MyThread();

        MyThreadthr2 = new MyThread();

 

        Threadtid1 = new Thread(new ThreadStart(thr1.Thread1) );

        Threadtid2 = new Thread(new ThreadStart(thr2.Thread1) );

 

        tid1.Name= "Thread 1";

        tid2.Name= "Thread 2";

 

       tid1.Priority = ThreadPriority.Highest;

        tid2.Priority= ThreadPriority.Lowest;

 

        try {

           tid1.Start();

           tid2.Start();

        } catch(ThreadStateException te) {

           Console.WriteLine(te.ToString() );

        }

 

       tid1.Join();

       tid2.Join();

 

       Console.WriteLine("End of Main");

    }

}

线程1的优先级是Highest线程2是Lowest。另外线程的优先级是AboveNormal, BelowNormal 和 Normal.

GetDomain()方法返回线程执行的执行文件的名。这个静态方法使用类名来访问。

示例16（Program16.cs）

using System;

using System.Threading;

 

public class MyThread {

    public voidThread1() {

       Console.WriteLine(Thread.GetDomain() );

        for (inti = 0; i < 10; i++) {

           Thread thr = Thread.CurrentThread;

           Console.WriteLine(i);

        }

    }

}

 

public class MyClass {

    public staticvoid Main() {

       Console.WriteLine("Before start thread");

 

        MyThreadthr1 = new MyThread();

 

        Threadtid1 = new Thread(new ThreadStart(thr1.Thread1) );

 

       tid1.Start();

 

    }

}

程序输出结果：

Before start thread
Name: prog16.exe
No context policies.

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