木子屋
 

标题: ManualResetEvent类用法小结

作者: dnawo

日期: 2014-08-18 00:17 AM

分类: Win编程

内容: 假设有一个程序中调用了三个异步方法，代码如下：
复制内容到剪贴板 程序代码public class Test
{
    public void Todo(string message)
    {
        Console.WriteLine("{0} {1}", DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss"), message);
    }
    private Action<string> _todo = null;
    public Test()
    {
        _todo = Todo;
    }
    public IAsyncResult BeginTodo(string message, AsyncCallback callback, object state)
    {
        return _todo.BeginInvoke(message, callback, state);
    }
    public void EndTodo(IAsyncResult ar)
    {
        _todo.EndInvoke(ar);
    }
}
public class Program
{
    static void callback1(IAsyncResult ar)
    {
        Test test = (Test)ar.AsyncState;
        test.EndTodo(ar);
    }
    static void callback2(IAsyncResult ar)
    {
        Test test = (Test)ar.AsyncState;
        test.EndTodo(ar);
    }
    static void callback3(IAsyncResult ar)
    {
        Test test = (Test)ar.AsyncState;
        test.EndTodo(ar);
    }
    static public void Main(string[] args)
    {
        Test test1 = new Test();
        test1.BeginTodo("test1", callback1, test1);
        Test test2 = new Test();
        test2.BeginTodo("test2", callback2, test2);
        Test test3 = new Test();
        test3.BeginTodo("test3", callback3, test3);
        Console.ReadKey();
    }
}
执行结果如下图所示：
也就是说，异步方法的执行顺序是不固定的，但有时我们希望它们能按顺序执行，修改代码如下：
复制内容到剪贴板 程序代码public class Program
{
    static void callback1(IAsyncResult ar)
    {
        Test test = (Test)ar.AsyncState;
        test.EndTodo(ar);
        Test test2 = new Test();
        test2.BeginTodo("test2", callback2, test2);
    }
    static void callback2(IAsyncResult ar)
    {
        Test test = (Test)ar.AsyncState;
        test.EndTodo(ar);
        Test test3 = new Test();
        test3.BeginTodo("test3", callback3, test3);
    }
    static void callback3(IAsyncResult ar)
    {
        Test test = (Test)ar.AsyncState;
        test.EndTodo(ar);
    }
    static public void Main(string[] args)
    {
        Test test1 = new Test();
        test1.BeginTodo("test1", callback1, test1);        
        Console.ReadKey();
    }
}
看着有没有感觉很乱？能不能让代码既像开始那样有条理，又能按顺序执行呢？ManualResetEvent类出场了：
复制内容到剪贴板 程序代码public class Program
{
    static ManualResetEvent done1 = new ManualResetEvent(false);
    static ManualResetEvent done2 = new ManualResetEvent(false);
    static ManualResetEvent done3 = new ManualResetEvent(false);
    static void callback1(IAsyncResult ar)
    {
        Test test = (Test)ar.AsyncState;
        test.EndTodo(ar);
        done1.Set();
    }
    static void callback2(IAsyncResult ar)
    {
        Test test = (Test)ar.AsyncState;
        test.EndTodo(ar);
        done2.Set();
    }
    static void callback3(IAsyncResult ar)
    {
        Test test = (Test)ar.AsyncState;
        test.EndTodo(ar);
        done3.Set();
    }
    static public void Main(string[] args)
    {
        Test test1 = new Test();
        test1.BeginTodo("test1", callback1, test1);
        done1.WaitOne(); //阻塞当前线程，待Set后继续执行
        Test test2 = new Test();
        test2.BeginTodo("test2", callback2, test2);
        done2.WaitOne(); //阻塞当前线程，待Set后继续执行
        Test test3 = new Test();
        test3.BeginTodo("test3", callback3, test3);
        done3.WaitOne(); //阻塞当前线程，待Set后继续执行
        Console.ReadKey();
    }
}

+ 查看当前日志评论 (0)

 

登录

────────────

木子屋

PJBlog3 v3.2.9.518 Inside.

Processed In 0.613 ms

标题: ManualResetEvent类用法小结

你没有权限发表评论

────────────

木子屋

PJBlog3 v3.2.9.518 Inside.

Processed In 0.613 ms

暂无评论

返回

────────────

木子屋

PJBlog3 v3.2.9.518 Inside.

Processed In 0.613 ms