异步能在一定场景中带性能的飞跃，同步调用性能，也以带来时间的节省。

先看一下被调用的api:

using Microsoft.AspNetCore.Mvc;using Microsoft.Extensions.Logging;using System;using System.Collections.Generic;using System.Linq;using System.Threading.Tasks;namespace WebAPI.Controllers{    [ApiController]    [Route("[controller]")]    public class HomeController : ControllerBase    {        private readonly ILogger
    
      _logger;        public HomeController(ILogger
     
       logger)        {            _logger = logger;        }        [HttpGet("/api001")]        public async Task
      
        GetAPI001()        {            _logger.LogInformation("GetAPI001");            await Task.Delay(1000);            return new JsonResult(new { result = true, data = "api001 返回成功" });        }        [HttpGet("/api002")]        public async Task
       
         GetAPI002()        {            _logger.LogInformation("GetAPI002");            await Task.Delay(1000);            if (DateTime.Now.Second % 2 == 0)            {                throw new Exception("api002异常");            }            return new JsonResult(new { result = true, data = "api002 返回成功" });        }        [HttpGet("/api003")]        public async Task
        
          GetAPI003()        {            _logger.LogInformation("GetAPI003");            await Task.Delay(1000);            return new JsonResult(new { result = true, data = "api003 返回成功" });        }    }}
        
       
      
     
    

调用时反序列化的实体类

class ResponseResult
    
         {        public bool Result { get; set; }        public string Message { get; set; }        public T Data { get; set; }    }
    

三个api的调用方法

private static async Task
    
      GetAPI001(HttpClient httpClient){    var content = await httpClient.GetStringAsync("http://localhost:5000/api001");    var result = JsonSerializer.Deserialize
     
      
       >(content, new JsonSerializerOptions { PropertyNameCaseInsensitive = true });    if (result.Result)    {        return result.Data;    }    else    {        return result.Message;    }}private static async Task
       
         GetAPI002(HttpClient httpClient){    var content = await httpClient.GetStringAsync("http://localhost:5000/api002");    var result = JsonSerializer.Deserialize
        
         
          >(content, new JsonSerializerOptions { PropertyNameCaseInsensitive = true }); if (result.Result) { return result.Data; } else { return result.Message; }}private static async Task
          
            GetAPI003(HttpClient httpClient){ var content = await httpClient.GetStringAsync("http://localhost:5000/api003"); var result = JsonSerializer.Deserialize
           
            
             >(content, new JsonSerializerOptions { PropertyNameCaseInsensitive = true }); if (result.Result) { return result.Data; } else { return result.Message; }}
            
           
          
         
        
       
      
     
    

同步的调用方式

static async Task SyncCall(){    using var httpClient = new HttpClient();    try    {        var result1 = await GetAPI001(httpClient);        WriteLine(result1);    }    catch (Exception exc)    {        WriteLine(exc.Message);    }    try    {        var result2 = await GetAPI002(httpClient);        Console.WriteLine(result2);    }    catch (Exception exc)    {        WriteLine(exc.Message);    }    try    {        var result3 = await GetAPI003(httpClient);        Console.WriteLine(result3);    }    catch (Exception exc)    {        WriteLine(exc.Message);    }}

调用方式

static async Task Main(string[] args){    while (true)    {        WriteLine("回车开始执行");        ReadLine();        var stopwatch = Stopwatch.StartNew();        await SyncCall();        WriteLine($"用时{stopwatch.ElapsedMilliseconds}ms");    }}

同步的调用，运行三次调用是三次的时间，3202ms，如果有异常不干扰其他api调用。

static async Task AsyncCall(){    using var httpClient = new HttpClient();    var allTasks = Task.WhenAll(GetAPI001(httpClient), GetAPI002(httpClient), GetAPI003(httpClient));    try    {        var results = await allTasks;        foreach (var result in results)        {            Console.WriteLine(result);        }    }    catch (Exception exc)    {        Console.WriteLine($"捕捉到的异常：{exc.Message}");    }    if (allTasks.Exception != null)    {        Console.WriteLine($"AllTasks异常：{ allTasks.Exception.Message}");    }}

同步调用成功时间是1156ms，时间缩短了，但三个api调用，如果有异常，则全军覆没。

先择适合的方式，打造更优的应用。