.net framework 4.5 +steeltoe+ springcloud（三）实现Hystrix断路器
在基于.net framework的服务客户端实现断路器功能，基本项目创建步骤可以参照我的另一篇发现和调用服务的笔记，地址：http://www.cnblogs.com/troytian/p/8621861.html
在客户端能实现服务调用基础上，我们首先需要在appsettings.json中添加Hystrix配置：
1 "hystrix": { 2 "command": { 3 "FortuneService": { 4 "threadPoolKeyOverride": "FortuneServiceTPool" 5 } 6 }, 7 "stream": { 8 "validate_certificates": false 9 } 10 },
在程序入口对断路器进行注册：
1 protected void Application_Start() 2 { 3 AreaRegistration.RegisterAllAreas(); 4 FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters); 5 RouteConfig.RegisterRoutes(RouteTable.Routes); 6 BundleConfig.RegisterBundles(BundleTable.Bundles); 7 8 ApplicationConfig.RegisterConfig("development"); 9 10 var builder = new ContainerBuilder(); 11 12 // Add Microsoft Options to container 13 builder.RegisterOptions(); 14 15 // Add Microsoft Logging to container 16 builder.RegisterLogging(ApplicationConfig.Configuration); 17 18 // Add Console logger to container 19 builder.RegisterConsoleLogging(); 20 21 // Register all the controllers with Autofac 22 builder.RegisterControllers(typeof(MvcApplication).Assembly); 23 24 // Register IDiscoveryClient, etc. 25 builder.RegisterDiscoveryClient(ApplicationConfig.Configuration); 26 27 // Register FortuneService Hystrix command 28 builder.RegisterHystrixCommand<IFetchServise, FetchServise>("fetchServise", ApplicationConfig.Configuration); 29 30 // Register Hystrix Metrics/Monitoring stream 31 //builder.RegisterHystrixMetricsStream(ApplicationConfig.Configuration); 32 33 // Create the Autofac container 34 var container = builder.Build(); 35 DependencyResolver.SetResolver(new AutofacDependencyResolver(container)); 36 37 // Get a logger from container 38 var logger = container.Resolve<ILogger<MvcApplication>>(); 39 40 logger.LogInformation("Finished container build, starting background services"); 41 42 // Start the Discovery client background thread 43 container.StartDiscoveryClient(); 44 45 // Start the Hystrix Metrics stream 46 //container.StartHystrixMetricsStream(); 47 48 logger.LogInformation("Finished starting background services"); 49 }
然后需要修改服务调用的方式，添加断路器fallback回调功能，FetchServise.cs：
1 public class FetchServise : HystrixCommand<string>, IFetchServise 2 { 3 DiscoveryHttpClientHandler _handler; 4 5 private const string RANDOM_FORTUNE_URL = "http://java-service/hi?name=tian"; 6 private ILogger<FetchServise> _logger; 7 8 public FetchServise(IHystrixCommandOptions options, IDiscoveryClient client, ILoggerFactory logFactory = null) : base(options) 9 { 10 _handler = new DiscoveryHttpClientHandler(client, logFactory?.CreateLogger<DiscoveryHttpClientHandler>()); 11 IsFallbackUserDefined = true; 12 _logger = logFactory?.CreateLogger<FetchServise>(); 13 } 14 15 public async Task<string> RandomFortuneAsync() 16 { 17 _logger?.LogInformation("RandomFortuneAsync"); 18 var result = await ExecuteAsync(); 19 _logger?.LogInformation("RandomFortuneAsync returning: " + result); 20 return result; 21 } 22 23 24 protected override async Task<string> RunAsync() 25 { 26 _logger?.LogInformation("RunAsync"); 27 var client = GetClient(); 28 var result = await client.GetStringAsync(RANDOM_FORTUNE_URL); 29 _logger?.LogInformation("RunAsync returning: " + result); 30 return result; 31 } 32 33 protected override async Task<string> RunFallbackAsync() 34 { 35 _logger?.LogInformation("RunFallbackAsync"); 36 return await Task.FromResult("服务断开，请稍后重试!"); 37 } 38 39 40 private HttpClient GetClient() 41 { 42 var client = new HttpClient(_handler, false); 43 return client; 44 } 45 }
现在我们断开java-service服务，再启动程序看看，会不会调用熔断机制，如果调用了则页面会显示我们设定好的提示语【服务断开，请稍后重试!】：
成功！
