异步学习小例子

 1、异步

void Test1()
        {
            ChangeText("==========================================================");
            ChangeText("i am washing left now ...");
        }

        // 执行Test 方法为 Test线程
        async void Test()
        {
            await playGameAsync(); // Main 线程遇到 await, 会拆分出 Test线程. 此时, Main线程回调到Main方法，Test线程继续执行 playGameAsync()方法
            ChangeText("==========================================================");
            ChangeText("i am washing right now ...");
        }

        // 执行 playGameAsync 为 play线程
        async Task playGameAsync()
        {
            await Task.Run(() =>
            { // Test 线程来这也会拆分两个线程(但是play线程回调时因为自己被await修饰了, 所以不能像Main线程一样立即向下执行),需要等待 play线程执行完成
                Task.Delay(3000).Wait();
                ChangeText("I am play game ..");
            });
            Task.Delay(3000).Wait();
            ChangeText("i am finish play game");
        }

        void ChangeText(string txt) {
            // 安全地更新Label的文本
            if (textBox1.InvokeRequired)
            {
                textBox1.Invoke(new Action(() =>
                {
                    textBox1.Text += txt + "\r\n";
                }));
            }
            else
            {
                textBox1.Text += txt + "\r\n";
            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Test(); // Main线程进入其中
            Test1();
            ChangeText("This is Main Finish  .....");
        }    

　　

2、异步停止全部没有结束的

 private async Task PerformAsyncOperation(CancellationToken cancellationToken,string str)
        {
            // 模拟长时间运行的操作
            for (int i = 0; i < 10000; i++)
            {
                cancellationToken.ThrowIfCancellationRequested();
                textBox1.Text += str + i + "\r\n";
                if (str == "A")
                {
                    await Task.Delay(1000); // 实际应用中这里会有长时间运行的代码
                }
                else {
                    await Task.Delay(100); // 实际应用中这里会有长时间运行的代码
                }
            }
        }

        private CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
        private void button1_Click(object sender, EventArgs e)
        {
            cancellationTokenSource = new CancellationTokenSource();
            // 启动异步操作
            Task asyncTask = PerformAsyncOperation(cancellationTokenSource.Token, "A");
            Task asyncTask1 = PerformAsyncOperation(cancellationTokenSource.Token, "B");
        }

        private void button2_Click(object sender, EventArgs e)
        {
            // 取消异步操作
            cancellationTokenSource.Cancel();
        }

　　

3、ThreadPool异步

private void button1_Click(object sender, EventArgs e)
        {
            // 启动异步操作
            ThreadPool.QueueUserWorkItem(AsyncOperation, "A");
            ThreadPool.QueueUserWorkItem(AsyncOperation, "B");
            ThreadPool.QueueUserWorkItem(AsyncOperation, "C");
        }

        private void AsyncOperation(object state)
        {
            for (var i = 0; i < 1000;i++){
                // 使用InvokeRequired检查是否需要跨线程操作
                if (textBox1.InvokeRequired)
                {
                    // 跨线程调用更新UI
                    textBox1.Invoke(new Action(() =>
                    {
                        textBox1.Text += "异步操作完成 " + state + i + " \r\n";
                    }));
                }
                else
                {
                    textBox1.Text += "异步操作完成 " + state + i + "\r\n";
                }
                if (state == "A")
                {
                    // 异步操作的代码，例如长时间运行的任务
                    Thread.Sleep(500); // 模拟耗时操作
                }
                else { 
                    // 异步操作的代码，例如长时间运行的任务
                    Thread.Sleep(100); // 模拟耗时操作
                }
            }
        }