async和await实现

一、描述

async ：返回值需要是Task 、Task<T> 、 void 或者VirtualTask<T>(.Net 7.0)。

Final、示例

using System.Net;
using System.Threading.Tasks;
class Program
{
    private static async Task RequestWeb(string url)
    {
        try
        {
            WebRequest webRequest = WebRequest.Create(url);
            WebResponse webResponse = await webRequest.GetResponseAsync();
            using (StreamReader reader = new StreamReader(webResponse.GetResponseStream()))
            {
                string text = await reader.ReadToEndAsync();
                Console.WriteLine(text);
            }


        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }

    }
    static void Main()
    {
        Task requestTask = RequestWeb("https://www.baidu.com");
        while (!requestTask.Wait(10))
        {
            Console.Write("*");
        }
    }
}

使用委托实现

using System.Net;
using System.Threading.Tasks;
class Program
{
    static void Main()
    {
        Func<string, Task> RequestWeb = async (url) =>
        {
            try
            {
                WebRequest webRequest = WebRequest.Create(url);
                WebResponse webResponse = await webRequest.GetResponseAsync();
                using (StreamReader reader = new StreamReader(webResponse.GetResponseStream()))
                {
                    string text = await reader.ReadToEndAsync();
                    Console.WriteLine(text);
                }


            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
        };


        Task requestTask = RequestWeb("https://www.baidu.com");
        while (!requestTask.Wait(10))
        {
            Console.Write("*");
        }
    }
}