using System;

using System.Diagnostics;using System.Threading;using System.Threading.Tasks;

namespace AsyncAwait

{ class Program { //http://www.cnblogs.com/sheng-jie/p/6471986.html // 3.3. 什么是前台线程 // 默认情况下，使用Thread.Start()方法创建的线程都是前台线程。前台线程能阻止应用程序的终结，只有所有的前台线程执行完毕，CLR才能关闭应用程序（即卸载承载的应用程序域）。前台线程也属于工作者线程。

//3.4. 什么是后台线程

// 后台线程不会影响应用程序的终结，当所有前台线程执行完毕后，后台线程无论是否执行完毕，都会被终结。一般后台线程用来做些无关紧要的任务（比如邮箱每隔一段时间就去检查下邮件，天气应用每隔一段时间去更新天气）。后台线程也属于工作者线程。

static void Main(string[] args)

{

//C# async关键字用来指定某个方法、Lambda表达式或匿名方法自动以异步的方式来调用。 Console.WriteLine("主线程启动，当前线程为：" + Thread.CurrentThread.ManagedThreadId); var task = GetLengthAsync();

Console.WriteLine("回到主线程，当前线程为：" + Thread.CurrentThread.ManagedThreadId);

Console.WriteLine("线程【" + Thread.CurrentThread.ManagedThreadId + "】睡眠5s:");

Thread.Sleep(5000); //将主线程睡眠5s

var timer = new Stopwatch();

timer.Start(); //开始计算时间

Console.WriteLine("task的返回值是" + task.Result);

timer.Stop(); //结束点，另外StopWatch还有Reset方法，可以重置。

Console.WriteLine("等待了：" + timer.Elapsed.TotalSeconds + "秒");//显示时间

Console.WriteLine("主线程结束，当前线程为：" + Thread.CurrentThread.ManagedThreadId);

//Console.WriteLine("主线程开始！");

//ForeBackGround();

//ThreadPoolTest(); Console.ReadKey(); }

private static async Task<int> GetLengthAsync()

{ Console.WriteLine("GetLengthAsync()开始执行，当前线程为：" + Thread.CurrentThread.ManagedThreadId);

var str = await GetStringAsync();

Console.WriteLine("GetLengthAsync()执行完毕，当前线程为：" + Thread.CurrentThread.ManagedThreadId);

return str.Length;

}

private static Task<string> GetStringAsync()

{ Console.WriteLine("GetStringAsync()开始执行，当前线程为：" + Thread.CurrentThread.ManagedThreadId); return Task.Run(() =>{ Console.WriteLine("异步任务开始执行，当前线程为：" + Thread.CurrentThread.ManagedThreadId);

Console.WriteLine("线程【" + Thread.CurrentThread.ManagedThreadId + "】睡眠10s");

Thread.Sleep(10000); //将异步任务线程睡眠10s

return "GetStringAsync()执行完毕";

});

}

public static void TaskDemo2()

{ Console.WriteLine("主线程ID：" + Thread.CurrentThread.ManagedThreadId); Task.Run(() => Console.WriteLine("Task对应线程ID：" + Thread.CurrentThread.ManagedThreadId)); Console.ReadLine(); }

public static void TaskDemo()

{ Console.WriteLine("主线程ID：" + Thread.CurrentThread.ManagedThreadId);

Task.Factory.StartNew(() => Console.WriteLine("Task对应线程ID：" + Thread.CurrentThread.ManagedThreadId));

Console.ReadKey(); }

/// <summary>

/// ThreadPool（线程池） /// </summary> public static void ThreadPoolTest() { WaitCallback workItem = state => Console.WriteLine("当前线程Id为：" + Thread.CurrentThread.ManagedThreadId);

for (int i = 0; i < 10; i++)

{ ThreadPool.QueueUserWorkItem(workItem); }

}

/// <summary>

/// 前台线程、后台线程 /// </summary> private static void ForeBackGround() { //创建前台工作线程 Thread t1 = new Thread(Task1); t1.Start();

//创建后台工作线程

Thread t2 = new Thread(new ParameterizedThreadStart(Task2)); t2.IsBackground = true; //设置为后台线程 t2.Start("传参"); }

private static void Task1()

{ Thread.Sleep(1000); //模拟耗时操作，睡眠1S Console.WriteLine("前台线程被调用！"); }

private static void Task2(object data)

{ Thread.Sleep(2000); //模拟耗时操作，睡眠2S Console.WriteLine("后台线程被调用！" + data); }

}

}