[C#] 多线程总结(结合进度条)

线程生命周期

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 + "\r\n";
    _msg += "当前托管线程的唯一标识：" + t.ManagedThreadId + "\r\n";
    _msg += "线程名称：" + t.Name + "\r\n";
    _msg += "当前线程的状态：" + t.ThreadState;
    MessageBox.Show("消息：\r\n" + _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);
    }
}

普通线程

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);
    }
}

线程池

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();
    }
}

BackgroundWorker

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;
}

Task

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());
}

异步委托

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();
}

SynchronizationContext

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

原文地址：https://www.cnblogs.com/zhaoshujie/p/9664915.html