12Feign整合断路器Hystrix

公众号：java 乐园

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