springcloud-eureka集群-整合hystrix框架整合feign

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")
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;
    }

@Autowired
    private final RestTemplate restTemplate;
    /**
     * 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/hello";
                        String result = restTemplate.getForObject(templateUrl, String.class);
                        System.out.println(result);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            };
            thread.start();
        }
        Thread.sleep(20000);
    }