c#Async与Await异步编程

柔情只为你懂 2022-12-11 09:28 221阅读 0赞

**这个是.NET 4.5的特性，所以最低要求.NET版本为4.5及以上。**

**Thread多线程异步编程例子**

public class Program
        { 
            static void Main(string[] args)
            { 
                Console.WriteLine("主线程测试开始..");
                Thread thread = new Thread(ThMethod);
                thread.Start();
                Thread.Sleep(1000);
                Console.WriteLine("主线程测试结束..");
                Console.ReadLine();
            }
    
    
            static void ThMethod()
            { 
                Console.WriteLine("异步执行开始");
                for (int i = 0; i < 5; i++)
                { 
                    Console.WriteLine("异步执行" + i.ToString() + "..");
                    Thread.Sleep(1000);
                }
                Console.WriteLine("异步执行完成");
            }
        }

**运行效果**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3MTkyNTcx_size_16_color_FFFFFF_t_70_pic_center]  
**使用Async与Await进行异步编程**

public class Program
        { 
            static void Main(string[] args)
            { 
                Console.WriteLine("主线程测试开始..");
                AsyncMethod();
                Thread.Sleep(1000);
                Console.WriteLine("主线程测试结束..");
                Console.ReadLine();
            }
    
            static async void AsyncMethod()
            { 
                Console.WriteLine("开始异步代码");
                var result = await MyMethod();
                Console.WriteLine("异步代码执行完毕");
            }
    
            static async Task<int> MyMethod()
            { 
                for (int i = 0; i < 5; i++)
                { 
                    Console.WriteLine("异步执行" + i.ToString() + "..");
                    await Task.Delay(1000); //模拟耗时操作
                }
                return 0;
            }
        }

只有拥有async才能在其内部使用await关键字。异步方法可以具有Task、Task<>或void的返回类型；

await关键字则是用于返回值是“可等待”类型(awaitable)的方法

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3MTkyNTcx_size_16_color_FFFFFF_t_70_pic_center]: /images/20221123/b7301c8ffd5e49c2b902b84ec79781a0.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3MTkyNTcx_size_16_color_FFFFFF_t_70_pic_center 1]: /images/20221123/2003b2f0a8794b32b117819bb58c68d3.png