异步委托的简单用例

//定义一个委托
static Func<int, int, string> delFunc = (a, b) =>
{
    Console.WriteLine("委托线程：" + Thread.CurrentThread.ManagedThreadId);
    return (a + b).ToString();
};

static void Main(string[] args)
{
    Console.WriteLine("主线程：" + Thread.CurrentThread.ManagedThreadId);

    //同步调用委托
    //string str = delFunc(3,4);//str = delFunc.Invoke(3, 4);

    //异步调用委托(原理：用线程池中线程，执行委托指向的方法)
    IAsyncResult ar = delFunc.BeginInvoke(3, 4, CallBackFn, "我是回调函数参数");//回调函数和回调函数参数
    //string result = delFunc.EndInvoke(ar);//EndInvoke方法会阻塞，等待异步委托的结束

    Console.ReadLine();
}

//异步委托执行完成后，回调的函数
static void CallBackFn(IAsyncResult iar)
{
    object obj = iar.AsyncState;//我是回调函数参数

    AsyncResult ar = iar as AsyncResult;
    Func<int, int, string> del = ar.AsyncDelegate as Func<int, int, string>;
    string result = del.EndInvoke(ar);//异步委托的结果，在这里委托已经执行完毕，不会再阻塞。

    Console.WriteLine("回调线程：" + Thread.CurrentThread.ManagedThreadId);
}