十一、RestTemplate+Ribbon整合断路器Hystrix

时间 2019-11-10

标签十一 resttemplate+ribbon resttemplate ribbon 整合断路器 hystrix 繁體版

原文原文链接

公众号： java乐园java

在微服务架构中，根据业务需求拆分红一个个的微小服务，而后服务与服务之间能够相互RPC远程调用。在Spring Cloud可使用RestTemplate+Ribbon或者Feign来进行RPC远程调用。为了保证服务高可用性，单个服务一般会进行集群部署。因为网络缘由或者自身的缘由，服务并不能保证百分之一百可用，若是服务方出现问题，调用这个服务就会出现线程阻塞，此时如有出现大量请求，致使服务方瘫痪。这时断路器就派上用场了。git

当对某个服务的调用的不可用达到一个阀值（Hystric 默认是5秒20次）断路器将会被自动被打开。断路打开后， fallback方法能够直接返回一个预先设置的固定值。github

一、新建项目sc-eureka-client-consumer-ribbon-hystrix，对应的pom.xml文件web

<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-ribbon</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>sc-eureka-client-consumer-ribbon</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>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>

        <!-- <dependency> 
                <groupId>org.springframework.cloud</groupId> 
                <artifactId>spring-cloud-starter-ribbon</artifactId> 
                <version>1.4.5.RELEASE</version> 
            </dependency> -->

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-ribbon</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-hystrix</artifactId>
            <version>1.4.5.RELEASE</version>
        </dependency> -->

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
            <version>2.0.1.RELEASE</version>
        </dependency>


    </dependencies>
</project>

备注：spring-cloud-starter-hystrix已经在spring cloud 2.x标注成过时。推荐使用spring-cloud-starter-netflix-hystrixspring

二、新建spring boot 启动类ConsumerApplication.java数据库

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.netflix.hystrix.EnableHystrix;

@SpringBootApplication
@EnableEurekaClient
@EnableHystrix
public class ConsumerHystrixApplication {
    
    public static void main(String[] args) {
        
        SpringApplication.run(ConsumerHystrixApplication.class, args);
        
    }

}

能够看出这个启动类只是《服务发现&服务消费者Ribbon》的启动类添加多了一个注解EnableHystrix（启动断路器）apache

三、编写服务类，并添加断路器注解bootstrap

package sc.consumer.service.impl;

import java.util.HashMap;
import java.util.Map;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

import com.github.andrewoma.dexx.collection.ArrayList;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;

import sc.consumer.model.User;
import sc.consumer.service.UserService;

@Service
public class UserServiceImpl implements UserService{

    @Autowired
    private RestTemplate restTemplate;
    
    @HystrixCommand(fallbackMethod = "getUserError")
    @Override
    public Map<String, Object> getUser(Long id) {
        return restTemplate.getForObject("http://sc-eureka-client-provider:8200/user/getUser/{1}", Map.class, id);
    }
    
    public Map<String, Object> getUserError(Long id){
        Map<String, Object> map = new HashMap<String, Object>();
        map.put("code", "000000");
        map.put("msg", "ok");
        User u = new User();
        u.setId(-1L);
        u.setUserName("failName");
        map.put("body", u);
        return map;
    }

    @HystrixCommand(fallbackMethod = "listUserError")
    @Override
    public Map<String, Object> listUser() {
        return restTemplate.getForObject("http://sc-eureka-client-provider:8200/user/listUser", Map.class);
    }
    
    public Map<String, Object> listUserError(){
        Map<String, Object> map = new HashMap<String, Object>();
        map.put("code", "000000");
        map.put("msg", "ok");
        map.put("body", new ArrayList<User>());
        return map;
    }

    @HystrixCommand(fallbackMethod = "addUserError")
    @Override
    public Map<String, Object> addUser(User user) {
        return restTemplate.postForObject("http://sc-eureka-client-provider:8200/user/addUser", user, Map.class);
    }

    public Map<String, Object> addUserError(User user){
        Map<String, Object> map = new HashMap<String, Object>();
        map.put("code", "000000");
        map.put("msg", "ok");
        map.put("body", 0);
        return map;
    }
    
    @HystrixCommand(fallbackMethod = "updateUserError")
    @Override
    public Map<String, Object> updateUser(User user) {
        restTemplate.put("http://sc-eureka-client-provider:8200/user/updateUser",user);
        Map<String, Object> map = new HashMap<String, Object>();
        map.put("code", "000000");
        map.put("msg", "ok");
        return map;
    }
    
    public Map<String, Object> updateUserError(User user){
        Map<String, Object> map = new HashMap<String, Object>();
        map.put("code", "000000");
        map.put("msg", "ok");
        map.put("body", 0);
        return map;
    }

    @HystrixCommand(fallbackMethod = "deleteUserError")
    @Override
    public Map<String, Object> deleteUser(Long id) {
        restTemplate.delete("http://sc-eureka-client-provider:8200/user/deleteUser/{id}", id);
        Map<String, Object> map = new HashMap<String, Object>();
        map.put("code", "000000");
        map.put("msg", "ok");
        return map;
    }
    
    public Map<String, Object> deleteUserError(Long id){
        Map<String, Object> map = new HashMap<String, Object>();
        map.put("code", "000000");
        map.put("msg", "ok");
        map.put("body", 0);
        return map;
    }

}

添加HystrixCommand注解，对应的参数fallbackMethod值为当方式服务方没法调用时，返回预设值得方法名。网络

四、新建配置文件bootstrap.yml和application.yml
bootstrap.yml架构

server:
  port: 5600

application.yml

spring:
  application:
    name: sc-eureka-client-consumer-ribbon-hystrix
    
eureka:
  instance:
    hostname: 127.0.0.1
  client:
    #因为该应用为注册中心,因此设置为false,表明不向注册中心注册本身
    registerWithEureka: true
    #因为注册中心的职责就是维护服务实例,它并不须要去检索服务,因此也设置为false
    fetchRegistry: true
    serviceUrl:
      defaultZone: http://127.0.0.1:5001/eureka/

五、其余项目文件参加下图

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

七、启动sc-eureka-client-consumer-ribbon-hystrix，并验证是否启动成功
方式一：查看日志

方式二：查看注册中心是否注册成功

八、验证断路器是否起做用
（1）服务提供者正常时访问：
http://127.0.0.1:5600/cli/user/getUser/4

正常返回数据库里的数据
（2）服务提供者关闭时访问：
http://127.0.0.1:5600/cli/user/getUser/4

对比两个返回的数据，能够看出服务提供者关闭时，返回的数据是在程序写死的数据，以下图：

其余方法能够自行按照以上方式进行验证。