Sentinel 异常统一处理

@ResourceSentinel 注解太麻烦，每个接口都加注解
Sentinel 限流返回的提示太不友好了，改成自定义的。

package com.tansun.springcloud.gateway.web.config;

import com.alibaba.csp.sentinel.adapter.spring.webflux.callback.BlockRequestHandler;
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.alibaba.fastjson.JSONObject;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.web.reactive.function.BodyInserters;
import org.springframework.web.reactive.function.server.ServerResponse;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;

@Configuration
public class SentinelExceptionConfig implements BlockRequestHandler {

        @Override
        public Mono<ServerResponse> handleRequest(ServerWebExchange serverWebExchange, Throwable throwable) {
            JSONObject resultObj = new JSONObject();
            if(throwable instanceof FlowException){
                resultObj.put("code",100);
                resultObj.put("msg","接口限流");
            }if(throwable instanceof DegradeException){
                resultObj.put("code",101);
                resultObj.put("msg","服务降级");
            }if(throwable instanceof ParamFlowException){
                resultObj.put("code",102);
                resultObj.put("msg","热点参数限流");
            }if(throwable instanceof SystemBlockException){
                resultObj.put("code",103);
                resultObj.put("msg","触发系统保护规则");
            }if(throwable instanceof AuthorityException){
                resultObj.put("code",104);
                resultObj.put("msg","授权规则不通过");
            }
            return ServerResponse.status(HttpStatus.BAD_GATEWAY)
                    .contentType(MediaType.APPLICATION_JSON)
                    .body(BodyInserters.fromValue(resultObj));
    };
}