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12、Feign整合断路器Hystrix

上编说了《RestTemplate+Ribbon整合断路器Hystrix》，这篇来看看如何Feign整合断路器Hystrix，Feign整合断路器Hystrix也是相对比较简单的。Feign默认已经自带断路器Hystrix，所以不需要像RestTemplate+Ribbon整合断路器Hystrix那样需要在SpringBoot的启动类添加注解。但是Feign自带断路器并没有打开，需要做些额外的配置。

feign:

   hystrix:

     enabled: true

1、新建项目sc-eureka-client-consumer-feign-hystrix，对应的pom.xml文件如下

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

<modelVersion>4.0.0</modelVersion>

 

<groupId>spring-cloud</groupId>

<artifactId>sc-eureka-client-consumer-feign</artifactId>

<version>0.0.1-SNAPSHOT</version>

<packaging>jar</packaging>

 

<name>sc-eureka-client-consumer-feign</name>

<url>http://maven.apache.org</url>

 

<parent>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-parent</artifactId>

<version>2.0.4.RELEASE</version>

</parent>

 

<dependencyManagement>

<dependencies>

<dependency>

<groupId>org.springframework.cloud</groupId>

<artifactId>spring-cloud-dependencies</artifactId>

<version>Finchley.RELEASE</version>

<type>pom</type>

<scope>import</scope>

</dependency>

 

</dependencies>

</dependencyManagement>

 

<properties>

<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

<maven.compiler.source>1.8</maven.compiler.source>

<maven.compiler.target>1.8</maven.compiler.target>

</properties>

 

<dependencies>

 

<!-- 说明是一个 eureka client -->

<dependency>

<groupId>org.springframework.cloud</groupId>

<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>

</dependency>

 

<dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-web</artifactId>

</dependency>

 

<!-- <dependency>

        <groupId>org.springframework.cloud</groupId>

        <artifactId>spring-cloud-starter-feign</artifactId>

    <version>1.4.5.RELEASE</version>

   </dependency> -->

 

<dependency>

<groupId>org.springframework.cloud</groupId>

<artifactId>spring-cloud-starter-openfeign</artifactId>

</dependency>

 

</dependencies>

</project>

备注：从继续关系可以看出spring-cloud-starter-openfeign已经集成断路器Hystrix

2、新建springboot启动类

package sc.consumer;

 

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

import org.springframework.cloud.openfeign.EnableFeignClients;

 

@SpringBootApplication

@EnableEurekaClient

@EnableFeignClients

public class ConsumerFeignApplication {

 

public static void main(String[] args) {

SpringApplication.run(ConsumerFeignApplication.class, args);

}

 

}

3、新建配置文件bootstrap.yml和application.yml

bootstrap.yml

server:

  port: 5800

application.yml

spring:

  application:

    name: sc-eureka-client-consumer-feign-hystrix

 

eureka:

  client:

    registerWithEureka: true #是否将自己注册到Eureka服务中，默认为true

    fetchRegistry: true #是否从Eureka中获取注册信息，默认为true

    serviceUrl:

      defaultZone: http://localhost:5001/eureka/

 

feign:

  hystrix:

enabled: true

说明：在application.yml配置文件添加了开启断路器Hystrix的配置项

4、新建服务消费者类UserService.java

package sc.consumer.service;

 

import java.util.Map;

 

import org.springframework.cloud.openfeign.FeignClient;

import org.springframework.web.bind.annotation.DeleteMapping;

import org.springframework.web.bind.annotation.GetMapping;

import org.springframework.web.bind.annotation.PathVariable;

import org.springframework.web.bind.annotation.PostMapping;

import org.springframework.web.bind.annotation.PutMapping;

import org.springframework.web.bind.annotation.RequestBody;

import org.springframework.web.bind.annotation.RequestMapping;

 

import sc.consumer.model.User;

import sc.consumer.service.hystrix.UserServiceHystrix;

 

@FeignClient(value="sc-eureka-client-provider", fallback=UserServiceHystrix.class)

public interface UserService {

 

@GetMapping("/user/getUser/{id}")

Map<String, Object> getUser(@PathVariable(value ="id") Long id);

 

@RequestMapping("/user/listUser")

Map<String, Object> listUser();

 

@PostMapping("/user/addUser")

Map<String, Object> addUser(@RequestBody User user);

 

@PutMapping("/user/updateUser")

Map<String, Object> updateUser(@RequestBody User user);

 

@DeleteMapping("/user/deleteUser/{id}")

Map<String, Object> deleteUser(@PathVariable(value ="id") Long id);

 

}

可以看到在该类的FeignClient注解上添加了一个属性fallback

5、新建断路器处理类UserServiceHystrix.java

package sc.consumer.service.hystrix;

 

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

 

import org.springframework.stereotype.Component;

 

import sc.consumer.model.User;

import sc.consumer.service.UserService;

 

@Component

public class UserServiceHystrix  implements UserService{

 

@Override

public Map<String, Object> getUser(Long id) {

Map<String, Object> result = new HashMap<String, Object>();

result.put("code", "000000");

result.put("msg", "success");

User u = new User();

u.setId(-1L);

u.setUserName("failBackName");

result.put("body", u);

return result;

}

 

@Override

public Map<String, Object> listUser() {

Map<String, Object> result = new HashMap<String, Object>();

result.put("code", "000000");

result.put("msg", "success");

List<User> list = new ArrayList<User>();

User u = new User();

u.setId(-1L);

u.setUserName("failBackName");

list.add(u);

result.put("body", list);

return result;

}

 

@Override

public Map<String, Object> addUser(User user) {

Map<String, Object> result = new HashMap<String, Object>();

result.put("code", "000000");

result.put("msg", "success");

result.put("body", 0);

return result;

}

 

@Override

public Map<String, Object> updateUser(User user) {

Map<String, Object> result = new HashMap<String, Object>();

result.put("code", "000000");

result.put("msg", "success");

result.put("body", 0);

return result;

}

 

@Override

public Map<String, Object> deleteUser(Long id) {

Map<String, Object> result = new HashMap<String, Object>();

result.put("code", "000000");

result.put("msg", "success");

result.put("body", 0);

return result;

}

 

}

该类实现了UserService接口，并实现了该接口的所有方法。

6、分别启动注册中心sc-eureka-server和服务提供者sc-eureka-client-provider

7、启动sc-eureka-client-consumer-feign-hystrix，并验证是否启动成功

方式一：查看日志看看对应的端口是启动

方式二：查看注册中心是否注册成功

8、使用postman验证断路器是否启用

上篇从服务提供者是否正常启动验证断路器是否启动，今天看看从数据库是否启动来验证断路器是否启动

（1）MySQL服务正常启动时访问：

http://127.0.0.1:5800/feign/user/listUser

（2）MySQL服务关闭时访问

http://127.0.0.1:5800/feign/user/listUser

再看下后台日志：

其他接口可以自行按照以上方式进行验证，看看断路器是否启动

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原文地址：https://www.cnblogs.com/happyhuangjinjin/p/12684100.html