async,await.task
示例代码:
private void button16_Click(object sender, EventArgs e) { Console.WriteLine("按钮开始" + Thread.CurrentThread.ManagedThreadId.ToString()); task1(); Console.WriteLine("按钮结束" + Thread.CurrentThread.ManagedThreadId.ToString()); } static async Task task1() { Console.WriteLine("task1开始" + Thread.CurrentThread.ManagedThreadId.ToString()); Thread.Sleep(5); task2(); Console.WriteLine("task1结束" + Thread.CurrentThread.ManagedThreadId.ToString()); } static async Task<string> task2() { Console.WriteLine("task2开始" + Thread.CurrentThread.ManagedThreadId.ToString()); Thread.Sleep(5); await Task.Run(() => { Thread.Sleep(10); Console.WriteLine("xxxxxxxxxxxxxxxx" + Thread.CurrentThread.ManagedThreadId.ToString()); }); Console.WriteLine("task2结束" + Thread.CurrentThread.ManagedThreadId.ToString()); return "ddd"; }
async修饰的函数,在被调用时都会开个线程执行,如果加了await当前线程就会等待task2执行完后在往下执行,不加的话,就会并发一起执行。
有些ORM或者API已经被分装成async的形式了,你为了等他们结束获取结果,需要await他们,而await关键字只能在async函数中使用,以此类推。。
如果调用有返回的task,在执行获取t.Result时就会等待task2执行完返回才继续往下。