[C#] 多线程总结(结合进度条)

线程生命周期(来源 w3cschool)

1. 未启动状态：当线程实例被创建但 Start 方法未被调用时的状况。
2. 就绪状态：当线程准备好运行并等待 CPU 周期时的状况。
3. 不可运行状态：
   • 已经调用 Sleep 方法
   • 已经调用 Wait 方法
   • 通过 I/O 操作阻塞
4. 死亡状态：当线程已完成执行或已中止时的状况。

Thread 常用方法:

• public void Interrupt()    中断处于 WaitSleepJoin 线程状态的线程。
• public void Join()         在继续执行标准的 COM 和 SendMessage 消息泵处理期间，阻塞调用线程，直到某个线程终止为止。
• public void Start()        开始一个线程
• public static void Sleep(int millisecondsTimeout)    让线程暂停一段时间

一 普通线程

分为两种，一种是不需要给子线程传参数，Thread t = new Thread(new ThreadStart(void () target)); 另一种是要给子线程传一个参数，Thread t = new Thread(new ParameterizedThreadStart(void (object) target));

// 普通线程
private void btn1_Click(object sender, EventArgs e)
{
	progressBar.Value = 0;
	Thread tt = new Thread(new ThreadStart(DoWork1));
	tt.Name = "不带参数普通线程";
	tt.Start();
	Thread t = new Thread(new ParameterizedThreadStart(DoWork2));
	t.Name = "带参数普通线程";
	t.IsBackground = true;
	t.Start(100);
	_msg += "当前线程的执行状态：" + t.IsAlive + "
";
	_msg += "当前托管线程的唯一标识：" + t.ManagedThreadId + "
";
	_msg += "线程名称：" + t.Name + "
";
	_msg += "当前线程的状态：" + t.ThreadState;
	MessageBox.Show("消息：
" + _msg, "提示", MessageBoxButtons.OK);
}
// 线程方法
private void DoWork1()
{
	for (int i = 0; i < 100; i++)
	{
		// 跨线程访问 UI，BeginInvoke 采用异步委托
		progressBar.BeginInvoke(new EventHandler((sender, e) =>
		{
			progressBar.Value = i;
		}), null);
	}
}
// 线程方法
private void DoWork2(object obj)
{
	for (int i = 0; i < (int)obj; i++)
	{
		progressBar.BeginInvoke(new EventHandler((sender, e) =>
		{
			progressBar.Value = i;
		}), null);
	}
}

二  线程池

public static bool QueueUserWorkItem(WaitCallback);

public static bool QueueUserWorkItem(WaitCallback, object);

线程池默认为后台线程（IsBackground）

private void btn3_Click(object sender, EventArgs e)
{
	ThreadPool.QueueUserWorkItem(DoWork2, 100);
	// 或者
	ThreadPool.QueueUserWorkItem((s) =>
	{
		int minWorkerThreads, minCompletionPortThreads, maxWorkerThreads, maxCompletionPortThreads;
		ThreadPool.GetMinThreads(out minWorkerThreads, out minCompletionPortThreads);
		ThreadPool.GetMaxThreads(out maxWorkerThreads, out maxCompletionPortThreads);
		MessageBox.Show(String.Format("WorkerThreads = {0} ~ {1}, CompletionPortThreads = {2} ~ {3}",
			minWorkerThreads, maxWorkerThreads, minCompletionPortThreads, maxCompletionPortThreads));
		DoWork2(100);
	});
}
// 线程方法
private void DoWork2(object obj)
{
	for (int i = 0; i < (int)obj; i++)
	{
		// Thread.Sleep(50);
		progressBar.BeginInvoke(new EventHandler((sender, e) =>
		{
			progressBar.Value = i;
		}), null);
	}
}

三  BackgroundWorker

private void btn4_Click(object sender, EventArgs e)
{
	progressBar.Value = 0;
	BackgroundWorker bw = new BackgroundWorker();
	bw.WorkerReportsProgress = true;// 是否报告进度更新
	// 线程执行
	bw.DoWork += new DoWorkEventHandler((obj, args) =>
	{
		for (int i = 0; i < 100; i++)
		{
			bw.ReportProgress(i);
		}
	});
	// UI主线程显示进度
	bw.ProgressChanged += (obj, progressChangedEventArgs) =>
	{
		progressBar.Value = progressChangedEventArgs.ProgressPercentage;
	};
	// 线程执行完成后的回调函数
	bw.RunWorkerCompleted += (obj, runWorkerCompletedEventArgs) =>
	{
		MessageBox.Show("子线程执行完成！");
	};
	if (!bw.IsBusy)
	{
		bw.RunWorkerAsync();
	}
}

三  Task（.NET 4.0以上版本）

参考博客 http://www.cnblogs.com/luxiaoxun/p/3280146.html

private void btn5_Click(object sender, EventArgs e)
{
	progressBar.Value = 0;
	Task<bool> t = new Task<bool>(maxValue => DoWork((int)maxValue), progressBar.Maximum);
	t.Start();
	t.Wait();
	// 任务完成后继续延续任务
	Task cwt = t.ContinueWith(task => MessageBox.Show("The result is " + t.Result));
}
// 线程方法
private bool DoWork(int maxValue)
{
	for (int n = 0; n < maxValue; n++)
	{
		progressBar.BeginInvoke(new EventHandler((sender, e) =>
		{
			progressBar.Value = n;
		}), null);
	}

	return true;
}

四  异步委托

参考博客 http://www.cnblogs.com/luxiaoxun/p/3280146.html

public delegate string MyDelegate(object arg);

private void btn6_Click(object sender, EventArgs e)
{
	MyDelegate myDelegate = new MyDelegate(DoWork3);
	IAsyncResult result = myDelegate.BeginInvoke(100, DoWork2Callback, "回调函数参数");

	// 异步执行完成
	string resultStr = myDelegate.EndInvoke(result);
}

// 线程函数
private string DoWork3(object arg)
{
	for (int n = 0; n < (int)arg; n++)
	{
		progressBar.BeginInvoke(new EventHandler((sender, e) =>
		{
			progressBar.Value = n;
		}), null);
	}

	return "Finished";
}

// 异步回调函数
private void DoWork2Callback(IAsyncResult arg)
{
	MessageBox.Show(arg.AsyncState.ToString());
}

五  附 跨线程访问UI之 SynchronizationContext (同步上下文)

private void btn2_Click(object sender, EventArgs e)
{
	SynchronizationContext context = SynchronizationContext.Current;
	new Thread(() =>
	{
		for (int i = 0; i < 100; i++)
		{
			// Send方法是发送一个异步请求消息
			//context.Send((s) =>
			//{
			//	progressBar.Value = i;
			//}, null);
			// Post方法是发送一个同步请求消息
			context.Post((s) =>
			{
				progressBar.Value = i;
			}, null);
		}
	}).Start();
}

六  参考资料：

☆多线程讲解 http://www.w3cschool.cc/csharp/csharp-multithreading.html

☆http://www.cnblogs.com/luxiaoxun/p/3280146.html