异常处理的种类

Web接口异常

主流框架的web接口都会被视为资源 实现BlockExceptionHandler中的handle方法即可,并将自定义的异常处理注册为bean

package com.atguigu.order.exception;

import com.alibaba.csp.sentinel.adapter.spring.webmvc_v6x.callback.BlockExceptionHandler;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.atguigu.common.R;
import com.fasterxml.jackson.databind.ObjectMapper;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import org.springframework.stereotype.Component;

import java.io.PrintWriter;
@Component
public class MyBlockExceptionHandler implements BlockExceptionHandler {
    private ObjectMapper objectMapper = new ObjectMapper();
    @Override
    public void handle(HttpServletRequest request, HttpServletResponse response, String s, BlockException e) throws Exception {
        response.setContentType("application/json;charset=utf-8");
        PrintWriter writer = response.getWriter();
        R error = R.error(500,s+"被sentinel限流");
        String json = objectMapper.writeValueAsString(error);
        writer.write(json);
    }
}

此时，web接口的异常会由自定义的异常类处理

@SentinelResource

对于使用@SentinelResource注解的资源，可以指定blockHandler或fallback指定兜底回调，若不指定，则走springboot的默认异常处理

@SentinelResource(value = "createOrder",blockHandler = "createOrderFallback")
    @Override
    public Order createOrder(Long productId, Long userId) {
//       Product product = getProductFromRemote(productId);
//        Product product = getProductFromRemoteWithLoadBalance(productId);
//        Product product = getProductFromRemoteWithLoadBalanceAnnotation(productId);
        //使用feign完成远程调用
        Product product = productFeignClient.getProductById(productId);
        Order order = new Order();
        order.setId(1L);


        // 总金额
        order.setTotalAmount(product.getPrice().multiply(new BigDecimal(product.getNum())));
        order.setUserId(userId);
        order.setNickName("zhangsan");
        order.setAddress("尚硅谷");
        //远程查询商品列表
        order.setProductList(Arrays.asList(product));
//
//        try {
//            SphU.entry("hahah");
//
//        } catch (BlockException e) {
//            //编码处理
//        }


        return order;
    }
    // 兜底回调
    public Order createOrderFallback(Long productId, Long userId, BlockException e) {
        Order order = new Order();
        order.setId(0L);
        order.setTotalAmount(new BigDecimal("0"));
        order.setUserId(userId);
        order.setNickName("未知用户");
        order.setAddress("异常信息："+e.getClass());

        return order;
    }

OpenFeign

OpenFeign的兜底回调可以通过@FeignClient的fallback属性指定,若不指定，则也会走springboot的默认异常处理

package com.atguigu.order.feign;

import com.atguigu.order.feign.fallback.ProductFeignClientFallback;
import com.atguigu.product.bean.Product;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;

@FeignClient(value = "service-product",fallback = ProductFeignClientFallback.class)
public interface ProductFeignClient {
    @GetMapping("/product/{id}")
    Product getProductById(@PathVariable("id") Long id);
}

package com.atguigu.order.feign.fallback;

import com.atguigu.order.feign.ProductFeignClient;
import com.atguigu.product.bean.Product;
import org.springframework.stereotype.Component;

import java.math.BigDecimal;
@Component
public class ProductFeignClientFallback implements ProductFeignClient {
    @Override
    public Product getProductById(Long id) {
        System.out.println("兜底回调....");
        Product product = new Product();
        product.setId(id);
        product.setPrice(new BigDecimal("0"));
        product.setProductName("未知商品");
        product.setNum(0);
        return product;
    }
}