springcloud-eureka集群-整合hystrix框架整合feign

深藏阁楼爱情的钟 2022-05-13 23:49 197阅读 0赞

继之前的项目继续扩展，整合hystrix和feign这两个框架。

1、修改服务器调用者的application.yml，增加如下代码

# 打开feign对hystrix的支持
    feign:
      hystrix:
        enabled: true
    
    # 配置hystrix
    hystrix:
      threadpool:
        default:
          coreSize: 10  #线程池核心线程数
      command:
        #IService#hello(): 设置某一个接口 default: 设置全部接口
        default:
          execution:
            isolation:
              thread:
                timeoutInMilliseconds: 1000 #超时时间
          circuitBreaker:
            requestVolumeThreshold: 3  #当在配置时间窗口内达到此数量后，进行短路。默认20个
            sleepWindowInMilliseconds: 5  #短路多久以后开始尝试是否恢复，默认5s
            errorThresholdPercentage: 50%  #出错百分比阈值，当达到此阈值后，开始短路。默认50%

2、修改之前的Iservice.java接口，增加fallback = IserviceFallback.class参数，这是接口的错误回调类

@FeignClient(value = "eureka-service", fallback = IServiceFallback.class)
    public interface IService {
    
        @GetMapping("/hello")
        String hello();
    
    }

3、创建错误回调类IserviceFallback.java

@Component
    public class IServiceFallback implements IService {
    
        @Override
        public String hello() {
            return "fallback_hello";
        }
    
    }

4、controller中编写一个测试接口，Thread.sleep(1000)，为了测试错误回退逻辑

@GetMapping(value = "/hello", produces = MediaType.APPLICATION_JSON_UTF8_VALUE)
    public String hello() throws InterruptedException {
        Thread.sleep(1000);
        String hello = iService.hello();
        return "hello : " + hello;
    }

5、如果有统一的业务处理方法，可以扩展hystrix的拦截器

在启动类上增加@ServletComponentScan注解来扫描拦截器

创建MyFilter.java

@WebFilter(urlPatterns = "/*", filterName = "hystrixFilter")
    @Component
    public class Myfilter implements Filter {
    
        @Override
        public void init(FilterConfig filterConfig) throws ServletException {}
    
        @Override
        public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse,
                FilterChain filterChain) throws IOException, ServletException {
    
            System.out.println("===================MyFilter====================");
            // 初始化 hystrix 请求上下文
            HystrixRequestContext hystrixRequestContext = HystrixRequestContext.initializeContext();
    
            /* 业务逻辑 */
    
            try{
                filterChain.doFilter(servletRequest, servletResponse);
            }catch (Exception e){
                e.printStackTrace();
            }finally {
                hystrixRequestContext.shutdown();
            }
        }
    
        @Override
        public void destroy() {}
    
    }

6、断路器的测试，修改Controller的hello()接口

@GetMapping(value = "/hello", produces = MediaType.APPLICATION_JSON_UTF8_VALUE)
    public String hello() throws InterruptedException {
            
        String hello = iService.hello();
        // 获取断路器对接口的开启状态，默认false
        HystrixCircuitBreaker hystrixCircuitBreaker = HystrixCircuitBreaker.Factory
                    .getInstance(HystrixCommandKey.Factory.asKey("IService#hello()"));
        System.out.println(hystrixCircuitBreaker.isOpen() + "");
        return "hello : " + hello;
    }

编写一个执行函数，同时启动20个线程来访问hello接口

/**
    * 测试断路器
    * 
    * @param args
    * @throws InterruptedException
    */
    public static void main(String[] args) throws InterruptedException {
    
    	RestTemplate restTemplate = new RestTemplate();
    	for (int i = 0; i < 20; i++) {
    		Thread thread = new Thread() {
    			@Override
    			public void run() {
    				try {
    					String templateUrl = "http://127.0.0.1:8666/sayHello";
    					String result = restTemplate.getForObject(templateUrl, String.class);
    					System.out.println(result);
    				} catch (Exception e) {
    					e.printStackTrace();
    				}
    			}
    		};
    		thread.start();
    	}
    	Thread.sleep(20000);
    }