C#中異步使用及回調

1. 一句話理解異步

   我叫你去吃飯，叫完你不去，那我就會一直等你，直到你和我一起去吃飯。這叫同步！

   我叫你去吃飯，叫完不管你去不去，我都不會等你，我自己去吃飯。這叫異步！

2. 異步使用

        static void Main(string[] args)
        {
            Console.WriteLine("----------主程序開始，線程ID是{0}-----------------", Thread.CurrentThread.ManagedThreadId);


            Action<string> action = t =>
            {
                for (int k = 0; k < 1000000000; k++)
                { }
                Console.WriteLine("當前參數是{1},當前線程是{0}", Thread.CurrentThread.ManagedThreadId,t);
            };

            action.BeginInvoke("異步參數",null,null);

            Console.WriteLine("----------主程序結束，線程ID是{0}-----------------", Thread.CurrentThread.ManagedThreadId);

            Console.Read();
        }

3. 異步回調

        static void Main(string[] args)
        {
            Console.WriteLine("----------主程序開始，線程ID是{0}-----------------", Thread.CurrentThread.ManagedThreadId);


            Action<string> action = t =>
            {
                for (int k = 0; k < 1000000000; k++)
                { }
                Console.WriteLine("當前參數是{1},當前線程是{0}", Thread.CurrentThread.ManagedThreadId,t);
            };
            AsyncCallback callback = t =>
            {
                Console.WriteLine("這里是回調函數 當前線程是{0}", Thread.CurrentThread.ManagedThreadId);
            };
            action.BeginInvoke("異步參數", callback, null);

            Console.WriteLine("----------主程序結束，線程ID是{0}-----------------", Thread.CurrentThread.ManagedThreadId);

            Console.Read();
        }

4. 異步回調帶參數

        static void Main(string[] args)
        {
            Console.WriteLine("----------主程序開始，線程ID是{0}-----------------", Thread.CurrentThread.ManagedThreadId);

            Action<string> action = t =>
            {
                for (int k = 0; k < 1000000000; k++)
                { }
                Console.WriteLine("當前參數是{1},當前線程是{0}", Thread.CurrentThread.ManagedThreadId,t);
            };
            AsyncCallback callback = t =>
            {
                Console.WriteLine(t.AsyncState);
                Console.WriteLine("這里是回調函數 當前線程是{0}", Thread.CurrentThread.ManagedThreadId);
            };
            action.BeginInvoke("異步參數", callback, "無名小蝦");

            Console.WriteLine("----------主程序結束，線程ID是{0}-----------------", Thread.CurrentThread.ManagedThreadId);

            Console.Read();
        }

5. 異步等待

第一種方式：IsCompleted

        static void Main(string[] args)
        {
            Console.WriteLine("----------主程序開始，線程ID是{0}-----------------", Thread.CurrentThread.ManagedThreadId);

            Action<string> action = t =>
            {
                for (int k = 0; k < 1000000000; k++)
                { }
                Console.WriteLine("當前參數是{1},當前線程是{0}", Thread.CurrentThread.ManagedThreadId,t);
            };
            AsyncCallback callback = t =>
            {
                Console.WriteLine(t.AsyncState);
                Console.WriteLine("這里是回調函數 當前線程是{0}", Thread.CurrentThread.ManagedThreadId);
            };
            IAsyncResult asyncResult = action.BeginInvoke("異步參數", callback, "無名小蝦");

            while (!asyncResult.IsCompleted)
            {
                Console.WriteLine("等待中......");
                Thread.Sleep(200);
            }

            Console.WriteLine("----------主程序結束，線程ID是{0}-----------------", Thread.CurrentThread.ManagedThreadId);

            Console.Read();
        }

第二種方式:WaitOne()

        static void Main(string[] args)
        {
            Console.WriteLine("----------主程序開始，線程ID是{0}-----------------", Thread.CurrentThread.ManagedThreadId);

            Action<string> action = t =>
            {
                for (int k = 0; k < 1000000000; k++)
                { }
                Console.WriteLine("當前參數是{1},當前線程是{0}", Thread.CurrentThread.ManagedThreadId,t);
            };
            AsyncCallback callback = t =>
            {
                Console.WriteLine(t.AsyncState);
                Console.WriteLine("這里是回調函數 當前線程是{0}", Thread.CurrentThread.ManagedThreadId);
            };
            IAsyncResult asyncResult = action.BeginInvoke("異步參數", callback, "無名小蝦");

            asyncResult.AsyncWaitHandle.WaitOne();

            Console.WriteLine("----------主程序結束，線程ID是{0}-----------------", Thread.CurrentThread.ManagedThreadId);

            Console.Read();
        }

第三種方式：EndInvoke()

        static void Main(string[] args)
        {
            Console.WriteLine("----------主程序開始，線程ID是{0}-----------------", Thread.CurrentThread.ManagedThreadId);

            Action<string> action = t =>
            {
                for (int k = 0; k < 1000000000; k++)
                { }
                Console.WriteLine("當前參數是{1},當前線程是{0}", Thread.CurrentThread.ManagedThreadId,t);
            };
            AsyncCallback callback = t =>
            {
                Console.WriteLine(t.AsyncState);
                Console.WriteLine("這里是回調函數 當前線程是{0}", Thread.CurrentThread.ManagedThreadId);
            };
            IAsyncResult asyncResult = action.BeginInvoke("異步參數", callback, "無名小蝦");

            action.EndInvoke(asyncResult);

            Console.WriteLine("----------主程序結束，線程ID是{0}-----------------", Thread.CurrentThread.ManagedThreadId);

            Console.Read();
        }

6. 異步返回值

主線程獲取到返回值

        static void Main(string[] args)
        {
            Console.WriteLine("----------主程序開始，線程ID是{0}-----------------", Thread.CurrentThread.ManagedThreadId);

            Func<string,string> func = t =>
            {
                string result = "這是我的返回值";

                for (int k = 0; k < 1000000000; k++)
                { }
                Console.WriteLine("當前參數是{1},當前線程是{0},返回的參數是 {2}", Thread.CurrentThread.ManagedThreadId,t, result);
                return result;
            };

            IAsyncResult asyncResult = func.BeginInvoke("異步參數", null, null);

            string res = func.EndInvoke(asyncResult);

            Console.WriteLine("獲取到返回值：{0}", res);

            Console.WriteLine("----------主程序結束，線程ID是{0}-----------------", Thread.CurrentThread.ManagedThreadId);

            Console.Read();
        }

回調獲取到返回值

        static void Main(string[] args)
        {
            Console.WriteLine("----------主程序開始，線程ID是{0}-----------------", Thread.CurrentThread.ManagedThreadId);

            Func<string,string> func = t =>
            {
                string result = "這是我的返回值";

                for (int k = 0; k < 1000000000; k++)
                { }
                Console.WriteLine("當前參數是{1},當前線程是{0},返回的參數是 {2}", Thread.CurrentThread.ManagedThreadId,t, result);
                return result;
            };

            AsyncCallback asyncCallback = t =>
            {
                string res = func.EndInvoke(t);
                Console.WriteLine("獲取到返回值：{0}", res);
            };

            func.BeginInvoke("異步參數", asyncCallback, null);


            Console.WriteLine("----------主程序結束，線程ID是{0}-----------------", Thread.CurrentThread.ManagedThreadId);

            Console.Read();
        }