流控组件Sentinel核心注解@SentinelResource中的参数fallback和blockHandler的使用方式

Posted 2021-06-23 IT挖掘机y

fallback顾名思义当Java程序运行发生错误时，由该参数定义的方法进行处理

    @GetMapping(value = "/consumer/{id}")
    @SentinelResource(value = "consumer", fallback = "handlerFallback")
    public ResponseEntity<String> consumerData(@PathVariable("id")Integer id) {
        ResponseEntity<String> entity = remoteService.getData(id);
        if (id <= 0) {
            throw new IllegalArgumentException("非法参数异常!");
        } else if (entity.getData() == null) {
            throw new NullPointerException("无响应数据，空指针异常!");
        }
        return entity;
    }

    public ResponseEntity<String> handlerFallback(Integer id, Throwable e) {
        return new ResponseEntity<>(443, "程序处理异常，开始执行fallback数据-->" +e.getMessage());
    }
  

blockHandler这个也很好明白，也就是当API违背控制台设置的阈值时，执行该参数定义的方法进行处理；说白了就是限流之后的处理

@GetMapping(value = "/consumer/{id}")
    @SentinelResource(value = "consumer",blockHandler = "blockHandler")
    public ResponseEntity<String> consumerData(@PathVariable("id")Integer id) {
        ResponseEntity<String> entity = remoteService.getData(id);
        if (id <= 0) {
            throw new IllegalArgumentException("非法参数异常!");
        } else if (entity.getData() == null) {
            throw new NullPointerException("无响应数据，空指针异常!");
        }
        return entity;
    }

    public ResponseEntity<String> blockHandler(BlockException blockException) {
        return new ResponseEntity<>(444, "QPS过高，服务开始熔断降级--->"+blockException.getMessage());
    }

那么问题来了，如果同时发生Java运行错误和限流，那么会走哪个默认的方法呢？

 @GetMapping(value = "/consumer/{id}")
    @SentinelResource(value = "consumer", fallback = "handlerFallback", blockHandler = "blockHandler")
    public ResponseEntity<String> consumerData(@PathVariable("id")Integer id) {
        ResponseEntity<String> entity = remoteService.getData(id);
        if (id <= 0) {
            throw new IllegalArgumentException("非法参数异常!");
        } else if (entity.getData() == null) {
            throw new NullPointerException("无响应数据，空指针异常!");
        }
        return entity;
    }

    public ResponseEntity<String> handlerFallback(Integer id, Throwable e) {
        return new ResponseEntity<>(443, "程序处理异常，开始执行fallback数据-->" +e.getMessage());
    }
    public ResponseEntity<String> blockHandler(Integer id, BlockException blockException) {
        return new ResponseEntity<>(444, "QPS过高，服务开始熔断降级--->"+blockException.getMessage());
    }

设置限流规则

当我持续刷新，它走的是blockHandler路线

记得在配置文件加入以下

feign:
  sentinel:
    enabled: true