8.8 zuul的过滤器以及回退

雨点打透心脏的1/2处 2023-07-03 10:40 13阅读 0赞

# zuul中四种标准过滤器类型： #

*  pre 在请求被调用之前，实现身份验证，记录调试
 *  routing 构建发送给微服务的请求
 *  post 路由到微服务之后执行，为响应添加header，收集统计信息和指标
 *  error 其他阶段发生错误的时候执行

# 编写自定义的过滤器 #

*  打印请求的日志

public class PreRequestLogFilter extends ZuulFilter { 
      private static final Logger LOGGER = LoggerFactory.getLogger(PreRequestLogFilter.class);
    
      @Override
      public String filterType() { 
        return FilterConstants.PRE_TYPE;
      }
    
      @Override
      public int filterOrder() { 
          //5,课本配置的是1，这里配置了4
        return FilterConstants.PRE_DECORATION_FILTER_ORDER - 1;
      }
    
      @Override
      public boolean shouldFilter() { 
        return true;
      }
    
      @Override
      public Object run() { 
        RequestContext ctx = RequestContext.getCurrentContext();
        HttpServletRequest request = ctx.getRequest();
        PreRequestLogFilter.LOGGER.info(String.format("send %s request to %s", request.getMethod(), request.getRequestURL().toString()));
        return null;
      }
    }

> PreRequestLogFilter.LOGGER.info 打日志
> 
> String.format(“send %s request to %s”, request.getMethod(), request.getRequestURL().toString())
> 
> String.format(“%%”,args1,args2）；

*  filterType 有值 pre route post error
 *  filterOrder 指定过滤器的执行顺序
 *  shouldFilter 判断过滤器是否要执行
 *  run 具体逻辑

## 添加到bean ##

@Bean
      public PreRequestLogFilter preRequestLogFilter() { 
        return new PreRequestLogFilter();
      }

# 禁用zuul过滤器 #

zuul.sendResponseFilter.post.disable=true

即是把这个sendResponseFilter过滤器禁用了

# zuul的容错与回退 #

http://localhost:8040/microservice-provider-user/1

http://localhost:8040/hystrix.stream

http://localhost:8030/hystrix.stream

zuul的hystrix监控的粒度是微服务

## 为zuul添加回退 ##

实现ZuulFallbackProvider，提供 ClientHttpResponse作为响应

Edgware版本之前的写法实现ZuulFallbackProvider，E版本或之后，用FallbackProvider

@Component
    public class MyFallbackProvider implements FallbackProvider { 
      @Override
      public String getRoute() { 
        // 表明是为哪个微服务提供回退，*表示为所有微服务提供回退
        return "*";
      }
    
      @Override
      public ClientHttpResponse fallbackResponse(Throwable cause) { 
        if (cause instanceof HystrixTimeoutException) { 
          return response(HttpStatus.GATEWAY_TIMEOUT);//504
        } else { 
          return this.fallbackResponse();
        }
      }
    
      @Override
      public ClientHttpResponse fallbackResponse() { //500
        return this.response(HttpStatus.INTERNAL_SERVER_ERROR);
      }
    
      private ClientHttpResponse response(final HttpStatus status) { 
        return new ClientHttpResponse() { 
          @Override
          public HttpStatus getStatusCode() throws IOException { 
            return status;
          }
    
          @Override
          public int getRawStatusCode() throws IOException { 
            return status.value();
          }
    
          @Override
          public String getStatusText() throws IOException { 
            return status.getReasonPhrase();
          }
    
          @Override
          public void close() { 
          }
    
          @Override
          public InputStream getBody() throws IOException { 
            return new ByteArrayInputStream("服务不可用，请稍后再试。".getBytes());
          }
    
          @Override
          public HttpHeaders getHeaders() { 
            // headers设定
            HttpHeaders headers = new HttpHeaders();
            MediaType mt = new MediaType("application", "json", Charset.forName("UTF-8"));
            headers.setContentType(mt);
            return headers;
          }
        };
      }
    }

# zuul的高可用 #

负载均衡： nginx，haProxy，f5

使用Sidecar 挎斗 整合非jvm微服务。

如使用 node.js