異步能在一定場景中帶性能的飛躍，同步調用性能，也以帶來時間的節省。

先看一下被調用的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<HomeController> _logger;public HomeController(ILogger<HomeController> logger){_logger = logger;}[HttpGet("/api001")]public async Task<IActionResult> 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<IActionResult> GetAPI002(){_logger.LogInformation("GetAPI002");await Task.Delay(1000);if (DateTime.Now.Second % 2 == 0){throw new Exception("api002異常");}return new JsonResult(new { result = true, data = "api002 返回成功" });}[HttpGet("/api003")]public async Task<IActionResult> GetAPI003(){_logger.LogInformation("GetAPI003");await Task.Delay(1000);return new JsonResult(new { result = true, data = "api003 返回成功" });}} }

調用時反序列化的實體類

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

三個api的調用方法

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

同步的調用方式

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);} }

調用方式

static async Task Main(string[] args) {while (true){WriteLine("回車開始執行");ReadLine();var stopwatch = Stopwatch.StartNew();await SyncCall();WriteLine($"用時{stopwatch.ElapsedMilliseconds}ms");} }

同步的調用，運行三次調用是三次的時間，3202ms，如果有異常不干擾其他api調用。

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($"捕捉到的異常：{exc.Message}");}if (allTasks.Exception != null){Console.WriteLine($"AllTasks異常：{ allTasks.Exception.Message}");} }

同步調用成功時間是1156ms，時間縮短了，但三個api調用，如果有異常，則全軍覆沒。

先擇適合的方式，打造更優的應用。

總結

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