/// <summary>
/// 開始執(zhí)行異步操作.
/// </summary>
/// <param name="param">委托方法的參數(shù)</param>
/// <param name="callback"></param>
/// <param name="object"></param>
/// <returns></returns>
IAsyncResult BeginInvoke(int param, AsyncCallback callback, Object @object);

/// <summary>
/// 結(jié)束執(zhí)行異步操作，并且返回異步操作結(jié)果.
/// </summary>
/// <param name="result"></param>
/// <returns>委托方法的返回類型</returns>
string EndInvoke(IAsyncResult result);

/// <summary>
/// 定義一個(gè)委托類型
/// </summary>
public delegate string Del();

/// <summary>
/// 任務(wù)類
/// </summary>
public class TaskClass
{
  public static string SleepTask()
  {
    Console.WriteLine("異步線程(ThreadId = {0})開始執(zhí)行睡眠任務(wù)，睡眠3s.\n", Thread.CurrentThread.ManagedThreadId);

    Thread.Sleep(3000);

    Console.WriteLine("異步線程(ThreadId = {0})蘇醒，睡眠任務(wù)執(zhí)行結(jié)束.\n", Thread.CurrentThread.ManagedThreadId);

    return "異步線程執(zhí)行成功.\n";
  }
}
  
/// <summary>
/// 異步編程實(shí)現(xiàn)類（主線程不會(huì)阻塞）
/// </summary>
public class AsynCallbackClass
{
  public static string result;

  public static void Main(string[] args)
  {
    Console.WriteLine("主線程(ThreadId = {0})開始執(zhí)行.\n", Thread.CurrentThread.ManagedThreadId);

    Del del = new Del(TaskClass.SleepTask);

    Console.WriteLine("主線程(ThreadId = {0})調(diào)用BeginInvoke()方法執(zhí)行異步任務(wù).\n", Thread.CurrentThread.ManagedThreadId);

    //開始執(zhí)行異步操作，TaskClass.SleepTask無(wú)參數(shù)，Callback為定義的回調(diào)方法.
    del.BeginInvoke(Callback, null);

    Console.WriteLine("主線程(ThreadId = {0})繼續(xù)執(zhí)行.\n", Thread.CurrentThread.ManagedThreadId);

    Thread.Sleep(5000);

    //輸出異步任務(wù)返回的結(jié)果
    Console.WriteLine(result);

    Console.WriteLine("主線程(ThreadId = {0})執(zhí)行結(jié)束.\n", Thread.CurrentThread.ManagedThreadId);
  }

  /// <summary>
  /// 回調(diào)方法
  /// </summary>
  /// <param name="ar"></param>
  public static void Callback(IAsyncResult ar)
  {
    AsyncResult asyncResult = ar as AsyncResult;

    if (asyncResult == null) { return; }

    Del del = asyncResult.AsyncDelegate as Del;

    if (del == null) { return; }

    Console.WriteLine("回調(diào)方法中調(diào)用EndInvoke()方法，獲取異步任務(wù)結(jié)果.\n", Thread.CurrentThread.ManagedThreadId);
    
    //結(jié)束執(zhí)行異步操作，并返回異步任務(wù)結(jié)果.
    result = del.EndInvoke(ar);
  }
}