springcloud中sentient整合openfeign组件

openfeign作为微服务各个模块之间调用的组件，如果服务提供方出现异常，会将错误返回给服务消费方，消费方可以通过sentinel的服务降级方法，对如果调用异常的情况进行处理

以下介绍下具体做法：

一、服务消费方必须整合openfeign，方法可以参考：https://www.cnblogs.com/qwg-/p/18007449

pom.xml中必须添加以下依赖：

   <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>

二、在application.yml文件中添加

server:
  port: 8090

spring:
  application:
    name: order-sentinel-openfeign

  cloud:
    sentinel:
      transport:
        dashboard: 127.0.0.1:8080
    nacos:
      discovery:
        server-addr: 127.0.0.1:8848
        username: nacos
        password: nacos
        namespace: public
feign:
  sentinel:
    enabled: true  #尤其是这个

三、代码

StockFeignService为feign接口

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
@FeignClient(name = "stock-service",path = "/stock",fallback = StockFeignFabackImpl.class)  //name为服务名称，path为接口路径
public interface StockFeignService {

    @GetMapping("/reduce2")
    String reduce2();
}

StockFeignFabackImpl为feign接口的实现类，该方法就是降级后执行的方法

@Component   // 注意需要添加到spring容器中
public class StockFeignFabackImpl implements StockFeignService {
    @Override
    public String reduce2() {
        return "被降级";
    }
}

被调用方（服务提供者）

@RestController
@RequestMapping("/stock")
public class StockController {

    @GetMapping("/reduce2")
    public String reduce2(){
        int a = 1/0;   //故意造异常
        System.out.println("扣减库存");
        return "扣减库存 " + port;
    }

controller测试demo

@RestController
@RequestMapping("/order")
public class OrderController {

    @Resource
    StockFeignService stockFeignService;


    @GetMapping("/openfeign")
    public String openfeign(){
        String msg = stockFeignService.reduce2();
        return "hello " + msg;
    }

测试请求

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