C# 异步编程的三种方式

一、通过委托实现异步

namespace Test1
{
    class AsyncDemo
    {
        public void async()
        {
            string i = "参数";
            Console.WriteLine("调用异步方法前");
            PostAsync(i);
            Console.WriteLine("调用异步方法后");
        }
        delegate void AsyncFoo(string i);
        private static void PostAsync(object o)
        {
            AsyncFoo caller = Myfunc;
            caller.BeginInvoke(o.ToString(), FooCallBack, caller);
        }
        private static void FooCallBack(IAsyncResult ar)
        {
            var caller = (AsyncFoo)ar.AsyncState;
            caller.EndInvoke(ar);
        }
        private static void Myfunc(string i)
        {
            Console.WriteLine("通过委托来实现异步编程的");
        }
    }
}

二、通过Task实现

namespace Test1
{
    class TaskDemo
    {
        public void taskDemo()
        {
            Console.WriteLine("主线程，线程ID："+Thread.CurrentThread.ManagedThreadId);
            //Task方式1
            Task task1= new Task(()=>TaskFunc1());
            task1.Start();
            //Task方式2
            var result = Task.Run<string>(()=>{ return TaskFunc2(); });
            Console.WriteLine(result.Result);
        }
        private static void TaskFunc1()
        {
            Console.WriteLine("Task方式1开启的线程ID:"+Thread.CurrentThread.ManagedThreadId);
            for(int i = 0; i < 100; i++)
            {
                Console.WriteLine(i);
            }
        }
        private static string  TaskFunc2()
        {
            for (int i = 100; i < 200; i++)
            {
                Console.WriteLine(i);
            }
            return "Task方式2开启的线程ID:"+ Thread.CurrentThread.ManagedThreadId;
        }
    }
}

三、通过await async实现

namespace Test1
{
    class awaitAsyncDemo
    {
        public void Demo()
        {
            Console.WriteLine("主线程，线程ID：" + Thread.CurrentThread.ManagedThreadId);
           
            var result =  AsyncFunc();
            Console.WriteLine(result.Result);
        }
        private static async Task<string> AsyncFunc()
        {
            return await Task.Run(() =>
            {
                Console.WriteLine("await/async的线程ID："+Thread.CurrentThread.ManagedThreadId);
                return "这是返回值";
            });
        }
        
    }
}