Task用法记录总结
1.创建Task的3种方法
1.1new方式实例化一个Task，需要通过Start方法启动
Task task = new Task(() =>
{
Thread.Sleep(100);
Console.WriteLine($"hello, task1的线程ID为{Thread.CurrentThread.ManagedThreadId}");
});
task.Start();
task.Start方式，每个task都在不同的线程中
代码：
private static void Main(string【】 args)
{
Console.WriteLine("Hello, World!");
Task task1 = new Task(() =>
{
Console.WriteLine("task1 is running on a thread id {0}. Is thread pool thread: {1}",
Thread.CurrentThread.ManagedThreadId,
Thread.CurrentThread.IsThreadPoolThread);
});
Task task2 = new Task(() =>
{
Console.WriteLine("task2 is running on a thread id {0}. Is thread pool thread: {1}",
Thread.CurrentThread.ManagedThreadId,
Thread.CurrentThread.IsThreadPoolThread);
});
Task task3 = new Task(() =>
{
Console.WriteLine("task3 is running on a thread id {0}. Is thread pool thread: {1}",
Thread.CurrentThread.ManagedThreadId,
Thread.CurrentThread.IsThreadPoolThread);
});
//不在同一个线程
task1.Start();
task2.Start();
task3.Start();
//在同一个线程
//task1.RunSynchronously();
//task2.RunSynchronously();
//task3.RunSynchronously();
Task.WaitAll(task1,task2,task3);
}
View Code
task.RunSynchronously方式，每个任务都在同一个线程。task会阻塞主线程
task.Start方式，不会阻塞主线程
1.2Task.Factory.StartNew(Action action)创建和启动一个Task
Task task2 = Task.Factory.StartNew(() =>
{
Thread.Sleep(100);
Console.WriteLine($"hello, task2的线程ID为{Thread.CurrentThread.ManagedThreadId}");
});
创建后自动运行Task
1.3Task.Run(Action action)将任务放在线程池队列，返回并启动一个Task
Task task3 = Task.Run(() =>
{
Thread.Sleep(100);
Console.WriteLine($"hello, task3的线程ID为{Thread.CurrentThread.ManagedThreadId}");
});
创建后自动运行Task
2.Task的Wait/WaitAny/WaitAll方法
task.Wait() 表示等待task执行完毕
Task.WaitAll(Task【】 tasks) 表示只有所有的task都执行完成了再解除阻塞
private static void Main(string【】 args)
{
Console.WriteLine("start");
Task task1 = new Task(() =>
{
Thread.Sleep(1000);
Console.WriteLine("task1 is running on a thread id {0}//代码效果参考：http://www.ezhiqi.com/zx/art_3426.html . Is thread pool thread: {1}",
Thread.CurrentThread.ManagedThreadId,
Thread.CurrentThread.IsThreadPoolThread);
});
Task task2 = new Task(() =>
{
Thread.Sleep(2000);
Console.WriteLine("task2 is running on a thread id {0}. Is thread pool thread: {1}",
Thread.CurrentThread.ManagedThreadId,
Thread.CurrentThread.IsThreadPoolThread);
});
Task task3 = new Task(() =>
{
Thread.Sleep(3000);
Console.WriteLine("task3 is running on a thread id {0}. Is thread pool thread: {1}",
Thread.CurrentThread.ManagedThreadId,
Thread.CurrentThread.IsThreadPoolThread);
});
// 不在同一个线程
task1.Start();
task2.Start();
task3.Start();
Task.WaitAll(task1,task2,task3);
Console.WriteLine("task 1 2 3 end");
}
task1 等待1秒，task2等待2秒 task3等待3秒，使用WaitAll，则会等所有任务执行完毕之后才结束。
Task.WaitAny(Task【】 tasks) 表示只要有一个task执行完毕就解除阻塞
task1 等待1秒，task2等待2秒 ，task3等待3秒，使用WaitAny，只要有一个task结束，就结束阻塞。这里task最先结束
3.Task的延续操作(WhenAny/WhenAll/ContinueWith)
Task.WhenAll(task1, task2, task3).ContinueWith((t) => {
//dosomething
Console.WriteLine("task 1 2 3 all End");
});
当task完成后执行某些操作。
4.带返回值的Task
private static int Main(string【】 args)
{
//1.new方式实例化一个Task
Task[span style="color: rgba(0, 0, 255, 1)">intint
{
Thread.Sleep(100);
Console.WriteLine($"hello, task1的线程ID为{Thread.CurrentThread.ManagedThreadId}");
return 12;
});
task.Start();
int ret = task.Result;
task.Wait();
Console.WriteLine(ret);
//2.Task.Run
Task[span style="color: rgba(0, 0, 255, 1)">intint
{
Thread.Sleep(1000);
Console.WriteLine($"hello, task2的线程ID为{Thread.CurrentThread.ManagedThreadId}");
return 13;
});
int ret2 = task2.Result;
Console.WriteLine(ret2);
//3.Task.Factory.StartNew
Task[span style="color: rgba(0, 0, 255, 1)">int
{
Thread.Sleep(100);
Console.WriteLine($"hello, task3的线程ID为{Thread.CurrentThread.ManagedThreadId}");
return 14;
});
int ret3 = task3.Result;
Console.WriteLine(ret3);
return 0;
}
5.异步async awit
private static void Main(string【】 args)
{
Console.WriteLine("begin download");
Task task = download();
Console.WriteLine("end download");
}
static async Task[span style="color: rgba(0, 0, 255, 1)">int
{
Console.WriteLine("开始");
await Task.Run(() => { Thread.Sleep(2222); });
Console.WriteLine("结束");
return 666;
}
可以看到主线程退出了，但download异步方法还没结束。
深入理解异步：
一文说通C#中的异步编程 - 老王Plus - 博客园 (cnblogs.com)
