在C#中編寫(xiě)多線程應(yīng)用程序，容易！

來(lái)自:www.kunwsoft.com

    以前在使用VB來(lái)實(shí)現(xiàn)多線程的時(shí)候，發(fā)現(xiàn)有一定的難度。雖然也有這樣那樣的方法，但都不盡人意，但在C#中，要編寫(xiě)多線程應(yīng)用程序卻相當(dāng)?shù)暮?jiǎn)單。這篇文章將作簡(jiǎn)要的介紹，以起到拋磚引玉的作用！
    .NET將關(guān)于多線程的功能定義在System.Threading名字空間中。因此，要使用多線程，必須先聲明引用此名字空間（using System.Threading;）。
       即使你沒(méi)有編寫(xiě)多線程應(yīng)用程序的經(jīng)驗(yàn)，也可能聽(tīng)說(shuō)過(guò)“啟動(dòng)線程”“殺死線程”這些詞，其實(shí)除了這兩個(gè)外，涉及多線程方面的還有諸如“暫停線程”“優(yōu)先級(jí)”“掛起線程”“恢復(fù)線程”等等。下面將一個(gè)一個(gè)的解釋。
    a.啟動(dòng)線程
    顧名思義，“啟動(dòng)線程”就是新建并啟動(dòng)一個(gè)線程的意思，如下代碼可實(shí)現(xiàn)：
    Thread thread1 = new Thread(new ThreadStart( Count));
    其中的 Count 是將要被新線程執(zhí)行的函數(shù)。
    b.殺死線程
    “殺死線程”就是將一線程斬草除根，為了不白費(fèi)力氣，在殺死一個(gè)線程前最好先判斷它是否還活著（通過(guò) IsAlive 屬性），然后就可以調(diào)用 Abort 方法來(lái)殺死此線程。
    c.暫停線程
    它的意思就是讓一個(gè)正在運(yùn)行的線程休眠一段時(shí)間。如 thread.Sleep(1000); 就是讓線程休眠1秒鐘。
    d.優(yōu)先級(jí)
    這個(gè)用不著解釋了。Thread類(lèi)中有一個(gè)ThreadPriority屬性，它用來(lái)設(shè)置優(yōu)先級(jí)，但不能保證操作系統(tǒng)會(huì)接受該優(yōu)先級(jí)。一個(gè)線程的優(yōu)先級(jí)可分為5種：Normal, AboveNormal, BelowNormal, Highest, Lowest。具體實(shí)現(xiàn)例子如下:
    thread.Priority = ThreadPriority.Highest;
    e.掛起線程
    Thread類(lèi)的Suspend方法用來(lái)掛起線程，知道調(diào)用Resume，此線程才可以繼續(xù)執(zhí)行。如果線程已經(jīng)掛起，那就不會(huì)起作用。
    if (thread.ThreadState = ThreadState.Running)
    {
         thread.Suspend();
    }
    f.恢復(fù)線程
    用來(lái)恢復(fù)已經(jīng)掛起的線程，以讓它繼續(xù)執(zhí)行，如果線程沒(méi)掛起，也不會(huì)起作用。
    if (thread.ThreadState = ThreadState.Suspended)
    {
         thread.Resume();
    }
    下面將列出一個(gè)例子，以說(shuō)明簡(jiǎn)單的線程處理功能。此例子來(lái)自于幫助文檔。
    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();
        }
    }
   
       此代碼產(chǎn)生的輸出類(lèi)似如下內(nèi)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.