使用C#轻松开发多线程应用，高效且简便

????????（欢迎访问www.kunwsoft.com）
??????? 以前在使用VB来实现多线程的时候，发现有一定的难度。虽然也有这样那样的方法，但都不尽人意，但在C#中，要编写多线程应用程序却相当的简单。这篇文章将作简要的介绍，以起到抛砖引玉的作用！
??????? .NET将关于多线程的功能定义在System.Threading名字空间中。因此，要使用多线程，必须先声明引用此名字空间（using System.Threading;）。
??????? 即使你没有编写多线程应用程序的经验，也可能听说过“启动线程”“杀死线程”这些词，其实除了这两个外，涉及多线程方面的还有诸如“暂停线程”“优先级”“挂起线程”“恢复线程”等等。下面将一个一个的解释。
??????? a.启动线程
??? 顾名思义，“启动线程”就是新建并启动一个线程的意思，如下代码可实现：
??? Thread thread1 = new Thread(new ThreadStart( Count));
??? 其中的 Count 是将要被新线程执行的函数。
??? b.杀死线程
??? “杀死线程”就是将一线程斩草除根，为了不白费力气，在杀死一个线程前最好先判断它是否还活着（通过 IsAlive 属性），然后就可以调用 Abort 方法来杀死此线程。
??? c.暂停线程
??? 它的意思就是让一个正在运行的线程休眠一段时间。如 thread.Sleep(1000); 就是让线程休眠1秒钟。
?? ?d.优先级
??? 这个用不着解释了。Thread类中有一个ThreadPriority属性，它用来设置优先级，但不能保证操作系统会接受该优先级。一个线程的优先级可分为5种：Normal, AboveNormal, BelowNormal, Highest, Lowest。具体实现例子如下:
??? thread.Priority = ThreadPriority.Highest;
?? ?e.挂起线程
??? Thread类的Suspend方法用来挂起线程，知道调用Resume，此线程才可以继续执行。如果线程已经挂起，那就不会起作用。
??? if (thread.ThreadState = ThreadState.Running)?
??? {
???????? thread.Suspend();
??? }
??? f.恢复线程
??? 用来恢复已经挂起的线程，以让它继续执行，如果线程没挂起，也不会起作用。
??? if (thread.ThreadState = ThreadState.Suspended)?
??? {
???????? thread.Resume();
??? }
??? 下面将列出一个例子，以说明简单的线程处理功能。此例子来自于帮助文档。
??? using System;
??? using System.Threading;

??? // Simple threading scenario:? Start a static method running
??? // on a second thread.
??? public class ThreadExample {
??????? // The ThreadProc method is called when the thread starts.
??????? // It loops ten times, writing to the console and yielding?
??????? // the rest of its time slice each time, and then ends.
??????? public static void ThreadProc() {
??????????? for (int i = 0; i <10; i++) {
??????????????? Console.WriteLine("ThreadProc: {0}", i);
??????????????? // Yield the rest of the time slice.
??????????????? Thread.Sleep(0);
??????????? }
??????? }

??????? public static void Main() {
??????????? Console.WriteLine("Main thread: Start a second thread.");
??????????? // The constructor for the Thread class requires a ThreadStart?
??????????? // delegate that represents the method to be executed on the?
??????????? // thread.? C# simplifies the creation of this delegate.
??????????? Thread t = new Thread(new ThreadStart(ThreadProc));
??????????? // Start ThreadProc.? On a uniprocessor, the thread does not get?
??????????? // any processor time until the main thread yields.? Uncomment?
??????????? // the Thread.Sleep that follows t.Start() to see the difference.
??????????? t.Start();
??????????? //Thread.Sleep(0);

??????????? for (int i = 0; i <4; i++) {
??????????????? Console.WriteLine("Main thread: Do some work.");
??????????????? Thread.Sleep(0);
??????????? }

??????????? Console.WriteLine("Main thread: Call Join(), to wait until ThreadProc ends.");
??????????? t.Join();
??????????? Console.WriteLine("Main thread: ThreadProc.Join has returned.? Press Enter to end program.");
??????????? Console.ReadLine();
??????? }
??? }

?????? 此代码产生的输出类似如下内容：

 Main thread: Start a second thread. Main thread: Do some work. ThreadProc: 0 Main thread: Do some work. ThreadProc: 1 Main thread: Do some work. ThreadProc: 2 Main thread: Do some work. ThreadProc: 3 Main thread: Call Join(), to wait until ThreadProc ends. ThreadProc: 4 ThreadProc: 5 ThreadProc: 6 ThreadProc: 7 ThreadProc: 8 ThreadProc: 9 Main thread: ThreadProc.Join has returned. Press Enter to end program.
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