Thread类的简单使用（Start,Sleep,Join,传参）

Thread 类创建并控制线程，设置其优先级并获取其状态。下面以4个例子介绍一下Thread类的常用方法：

1. Start——启动线程。

using System;
using System.Threading;

class Example
{
    public static void Loop()
    {
        for (int j = 1; j <= 20; j++)
        {
            Console.WriteLine(Thread.CurrentThread.Name + "   j =  " + j);
        }
    }

    public static void Main()
    {
        Thread.CurrentThread.Name = "MainThread";
        Thread newThread = new Thread(new ThreadStart(Loop));
        newThread.Name = "NewThread";
        newThread.Start();        
        for (int i = 1; i <= 20; i++)
        {
            Console.WriteLine(Thread.CurrentThread.Name + "   i =  " + i);
        }      

        Console.ReadLine();
    }
}

可以看到，NewThread启动后，与MainThread相互竞争使用CPU。这就是Windows系统的抢占式CPU竞争策略。

2. Sleep——将当前线程挂起指定的时间

using System;
using System.Threading;

class Example
{
    public static void Loop()
    {
        for (int j = 1; j <= 20; j++)
        {
            Console.WriteLine(Thread.CurrentThread.Name + "   j =  " + j);
        }
    }

    public static void Main()
    {
        Thread.CurrentThread.Name = "MainThread";
        Thread newThread = new Thread(new ThreadStart(Loop));
        newThread.Name = "NewThread";
        newThread.Start();
        for (int i = 1; i <= 20; i++)
        {
            if (i % 3 == 0)
                Thread.Sleep(1);
            else
                Console.WriteLine(Thread.CurrentThread.Name + "   i =  " + i);
        }

        Console.ReadLine();
    }
}

可以看到，i=3时，MainThread挂起1ms，这1ms内NewThread占用CPU，j从1跑到了11。1ms后MainThread“醒了”，重新与NewThread竞争CPU的使用，结果夺回了CPU的使用权，i从4跑到了5。i=6时，又经历了上述过程。。。
想要更好的理解Sleep方法，请阅读http://www.cnblogs.com/ilove/archive/2008/04/07/1140419.html。 

3. Join——暂停当前线程，直到调用Join方法的线程终止为止。

using System;
using System.Threading;

class Example
{
    public static void Loop()
    {
        for (int j = 1; j <= 10; j++)
        {
            Console.WriteLine(Thread.CurrentThread.Name + "   j =  " + j);
        }
    }

    public static void Main()
    {
        Thread.CurrentThread.Name = "MainThread";
        Thread newThread = new Thread(new ThreadStart(Loop));
        newThread.Name = "NewThread";
        for (int i = 1; i <= 10; i++)
        {
            if (i == 5)
            {
                newThread.Start();
                newThread.Join();
            }
            else
            {
                Console.WriteLine(Thread.CurrentThread.Name + "   i =  " + i);
            }
        }

        Console.ReadLine();
    }
}

 

可以看到，i=5时，NewThread开始并调用Join方法暂停了MainThread，直到NewThread终止，MainThread才恢复执行。

4. 为线程传递参数

using System;
using System.Threading;

class Example
{
    public static void Say(string message)
    {
        Console.WriteLine("I'm " + Thread.CurrentThread.Name + ".");
        Console.WriteLine("I got a message: " + message);
    }

    public static void Main()
    {
        Thread.CurrentThread.Name = "MainThread";
        Thread newThread = new Thread(new ThreadStart(() => Say("Hello!")));//为线程传递参数的最简单的方法莫过于执行一个lambda表达式
        newThread.Name = "NewThread";
        newThread.Start();
        newThread.Join();

        Console.ReadLine();
    }
}

这里使用lambda表达式为NewThread传递参数，还有另外的方法@http://www.cnblogs.com/LoveJenny/archive/2011/05/21/2052556.html。

说明：以上部分实验不具有重复性，请读者不要纠结于：自己实验的结果与本文不同。