委托(4)

并行委托

并行委托有Parallel.For()、Parallel.Foreach<>()、Parallel.Invoke()三种写法，应用并行可以缩短程序运行时间。
Parallel.For()写法：

static void Main(string[] args){    Stopwatch watch = new Stopwatch();    watch.Start();    //【写法一】    //Parallel.For(1, 11, new DelegateHelper().Test);    //【写法二】    Parallel.For(1, 11, delegate(int i) {         Console.WriteLine(i); Thread.Sleep(1000);     });    watch.Stop();    //非并行情况下循环10次需要10s，因为每次执行Test方法会休息1s    Console.WriteLine("花费时间：" + watch.Elapsed.Seconds);    Console.ReadKey();}public void Test(int num){    Console.WriteLine(num);    Thread.Sleep(1000);}

运行截图如下：

Parallel.Foreach<>()写法：

static void Main(string[] args){    Stopwatch watch = new Stopwatch();    watch.Start();    //【写法一】    int[] nums = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };    string[] strArray = { "a","b","c","d","e","f","g"};    //Parallel.ForEach<int>(nums, new DelegateHelper().Test);    //【写法二】    Parallel.ForEach<int>(nums, delegate(int num)    {        Console.WriteLine(num);        Thread.Sleep(1000);    });     //遍历string数组    Parallel.ForEach<string>(strArray, delegate(string str)    {        Console.WriteLine(str);        Thread.Sleep(1000);    });     watch.Stop();    //非并行情况下循环10次需要10s，因为每次执行Test方法会休息1s    Console.WriteLine("花费时间：" + watch.Elapsed.Seconds);    Console.ReadKey();}public void Test(int num){    Console.WriteLine(num);    Thread.Sleep(1000);}

运行结果如下：

Parallel.Invoke()写法：

static void Main(string[] args){    Stopwatch watch = new Stopwatch();    watch.Start();    //【写法一】    Action[] actions=new Action[]{        new Action(delegate(){Console.WriteLine("方法一");Thread.Sleep(1000);}),        new Action(delegate(){Console.WriteLine("方法二");Thread.Sleep(1000);}),        new Action(delegate(){Console.WriteLine("方法三");Thread.Sleep(1000);})    };    Parallel.Invoke(actions);    //【写法二】    Parallel.Invoke(Func1, Func2, Func3);      watch.Stop();    //非并行情况下循环10次需要10s，因为每次执行Test方法会休息1s    Console.WriteLine("花费时间：" + watch.Elapsed.Seconds);    Console.ReadKey();}public static void Func1(){    Console.WriteLine("方法一"); Thread.Sleep(1000);}public static void Func2(){    Console.WriteLine("方法二"); Thread.Sleep(1000);}public static void Func3(){    Console.WriteLine("方法三"); Thread.Sleep(1000);}

运行截图如下：

异步委托

异步委托可以异步执行委托的方法，不过是用EndInvoke()方法等待委托执行完毕然后获取返回值。
EndInvoke()会阻塞主线程，等到委托的方法执行完毕后，程序才会继续执行，不过EndInvoke()之前的代码会正常执行，一般用于执行相互独立的模块，BeginInvoke异步执行独立模块A，BeginInvoke之后EndInvoke之前执行独立模块B，等到两模块都执行完毕后来进行下一步的操作，这样可以提高一点效率。
没有回调函数：

public void AsyncDelegateNoCallback(){    SayHiEventHandler sayHi = SayHiByChinese;    IAsyncResult iasyncResult = sayHi.BeginInvoke("蝈蝈", null, null);    Console.WriteLine("do some things......");    //有EndInvoke结果如图一，没EndInvoke结果如图二    //string result = sayHi.EndInvoke(iasyncResult);    Console.WriteLine("继续执行");}public string SayHiByChinese(string name){    Console.WriteLine("你好：" + name);    Thread.Sleep(2000);    return "成功";}

有回调函数：
异步委托所需的回调函数其实就是无返回值、包含一个IAsyncResult类型参数的委托。
回调函数是在委托执行完毕之后才执行，此时EndInvoke()将不会再花费大量时间，因为委托已经执行完毕可直接获取结果。

public void AsyncDelegate(){    SayHiEventHandler sayHi = SayHiByChinese;    IAsyncResult iasyncResult = sayHi.BeginInvoke("蝈蝈",CallBackFunc,"回调函数所需参数");        //回调函数中有EndInvoke，此处不应该再写一次    //sayHi.EndInvoke(iasyncResult);    Console.WriteLine("继续执行主线程");}public void AsyncDelegateAnonymous(){    SayHiEventHandler sayHi = SayHiByChinese;    IAsyncResult iasyncResult = sayHi.BeginInvoke("蝈蝈", new AsyncCallback(delegate(IAsyncResult ias) {        AsyncResult asyncResult = ias as AsyncResult;        //param="回调函数所需参数"        string param = asyncResult.AsyncState.ToString();        SayHiEventHandler current = asyncResult.AsyncDelegate as SayHiEventHandler;        Console.WriteLine("do other things......");        //result="成功"        string result = current.EndInvoke(asyncResult);        Console.WriteLine("继续执行回调函数");    }), "回调函数所需参数");         //回调函数中有EndInvoke，此处不应该再写一次    //sayHi.EndInvoke(iasyncResult);    Console.WriteLine("继续执行主线程");}public void CallBackFunc(IAsyncResult ias){    AsyncResult asyncResult = ias as AsyncResult;    //param="回调函数所需参数"    string param = asyncResult.AsyncState.ToString();    SayHiEventHandler current = asyncResult.AsyncDelegate as SayHiEventHandler;    Console.WriteLine("do other things......");    //result="成功"    string result = current.EndInvoke(asyncResult);    Console.WriteLine("继续执行回调函数");}

运行结果如图：