C#中异步回调函数用法

普通回调：

https://blog.csdn.net/sajiazaici/article/details/78702144

 

异步回调：

static void Main(string[] args) {  Func showMessage = ShowMessage;  //设置了回调函数Completed,不能有返回值  IAsyncResult result = showMessage.BeginInvoke("测试异步委托",new AsyncCallback(Completed),null);  //半段异步是否结束  while(!result.IsCompleted)  {   Console.WriteLine("主线程可以进行其它的操作！");  }  Console.ReadLine(); } static string ShowMessage(string x) {  string current = string.Format("当前线程id为{0}",Thread.CurrentThread.ManagedThreadId);  Thread.Sleep(3000);  return string.Format("{0},输入为{1}", current, x); } static void Completed(IAsyncResult result) {  Console.WriteLine("异步完成！");  //获取委托对象，并用EndInvoke方法获取返回结果  AsyncResult _result = (AsyncResult) result;  Func showMessage = (Func) _result.AsyncDelegate;  //结束异步操作并输出  Console.WriteLine(showMessage.EndInvoke(_result)); }