【Spring Cloud、Sentinel】搭建Spirng Cloud项目（十三）：Spring Boot服务自定义Sentine限流异常

一、背景介绍

Sentinel在默认情况下，URL触发限流后会直接返回 Blocked by Sentinel (flow limiting)，提示不友好，所以需要自定义返回格式。

二、具体方案

方案一：在Spring Boot项目中，直接使用统一异常处理

/**
     * 替换默认流控提示内容:Blocked by sentinel(flow limiting)
     * 流控规则异常处理
     * 如果 @SentinelResource中定义了 blockHandler 和 faidback 属性，则此处不会捕获，以为 blockHandler 和 failback的优先级最高。
     * 
     */
    @ExceptionHandler({FlowException.class})
    public R handleRRException(FlowException e){
        logger.error(RespConstant.RESP_MSG_FLOW_LIMITING_EXCEPTION, e);
        return RespUtils.commonHandle(RespConstant.RESP_CODE_FLOW_LIMITING_EXCEPTION, RespConstant.RESP_MSG_FLOW_LIMITING_EXCEPTION);
    }
 
    /**
     * 服务降级异常处理
     */
    @ExceptionHandler({DegradeException.class})
    public R handleRRException(DegradeException e){
        logger.error(RespConstant.RESP_MSG_DEGRADE_EXCEPTION, e);
        return RespUtils.commonHandle(RespConstant.RESP_CODE_DEGRADE_EXCEPTION, RespConstant.RESP_MSG_DEGRADE_EXCEPTION);
    }
 
    /**
     * 处理流量控制异常处理
     */
    @ExceptionHandler({AuthorityException.class})
    public R handleRRException(AuthorityException e){
        logger.error(RespConstant.RESP_MSG_AUTHORITY_EXCEPTION, e);
        return RespUtils.commonHandle(RespConstant.RESP_CODE_AUTHORITY_EXCEPTION, RespConstant.RESP_MSG_AUTHORITY_EXCEPTION);
    }
 
    /**
     * 处理流量控制异常处理
     */
    @ExceptionHandler({ParamFlowException.class})
    public R handleRRException(ParamFlowException e){
        logger.error(RespConstant.RESP_MSG_PARAM_FLOW_EXCEPTION, e);
        return RespUtils.commonHandle(RespConstant.RESP_CODE_PARAM_FLOW_EXCEPTION, RespConstant.RESP_MSG_PARAM_FLOW_EXCEPTION);
    }
 
    /**
     * 处理流量控制异常处理
     */
    @ExceptionHandler({SystemBlockException.class})
    public R handleRRException(SystemBlockException e){
        logger.error(RespConstant.RESP_MSG_SYSTEM_BLOCK_EXCEPTION, e);
        return RespUtils.commonHandle(RespConstant.RESP_CODE_SYSTEM_BLOCK_EXCEPTION, RespConstant.RESP_MSG_SYSTEM_BLOCK_EXCEPTION);
    }

方案二：实现UrlBlockHandler接口

**package com.cyun.common.config.sentinel;

import cn.hutool.json.JSONUtil;
import com.alibaba.csp.sentinel.adapter.spring.webmvc.callback.BlockExceptionHandler;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.alibaba.csp.sentinel.slots.block.authority.AuthorityException;
import com.alibaba.csp.sentinel.slots.block.degrade.DegradeException;
import com.alibaba.csp.sentinel.slots.block.flow.FlowException;
import com.alibaba.csp.sentinel.slots.block.flow.param.ParamFlowException;
import com.alibaba.csp.sentinel.slots.system.SystemBlockException;
import com.cyun.core.result.ResultVO;
import org.springframework.http.HttpStatus;
import org.springframework.stereotype.Component;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


/**
 * 自定义sentinel异常返回信息
 *
 * @author panfu.he
 */
@Component
public class SentinelBlockHandler implements BlockExceptionHandler {

    @Override
    public void handle(HttpServletRequest request, HttpServletResponse response, BlockException ex) throws Exception {
        String msg = null;
        if (ex instanceof FlowException) {
            msg = "限流了";
        } else if (ex instanceof DegradeException) {
            msg = "降级了";
        } else if (ex instanceof ParamFlowException) {
            msg = "热点参数限流";
        } else if (ex instanceof SystemBlockException) {
            msg = "系统规则（负载/...不满足要求）";
        } else if (ex instanceof AuthorityException) {
            msg = "授权规则不通过";
        }

        response.setContentType("text/json;charset=utf-8");
        response.getWriter().print(JSONUtil.toJsonStr(ResultVO.error(HttpStatus.TOO_MANY_REQUESTS.value(), msg)));
    }
}

方案三：跳转降级界面测试（已过时）

spring:
  application:
    name: springboot-sentinel-sample
  cloud:
    sentinel:
      transport:
        dashboard: 127.0.0.1:7777
      servlet:
        block-page: /goerror

@GetMapping("/goerror")
private String error(){
    return "error";
}