SpringCloud之Ribbon负载均衡及Feign消费者调用服务

目的：

　　　　微服务调用Ribbon

　　　　Ribbon负载均衡

　　　　Feign简介及应用

---

微服务调用Ribbon

　　Ribbon简介

　　1. 负载均衡框架，支持可插拔式的负载均衡规则

　　2. 支持多种协议，如HTTP、UDP等

　　3. 提供负载均衡客户端

Ribbon是Netflix发布的负载均衡器，它有助于控制HTTP和TCP的客户端的行为。为Ribbon配置服务提供者地址后，Ribbon就可基于某种负载均衡算法，自动地帮助服务消费者去请求。Ribbon默认为我们提供了很多负载均衡算法，例如轮询、随机等。当然，我们也可为Ribbon实现自定义的负载均衡算法。

在Spring Cloud中，当Ribbon与Eureka配合使用时，Ribbon可自动从Eureka Server获取服务提供者地址列表，并基于负载均衡算法，请求其中一个服务提供者实例。展示了Ribbon与Eureka配合使用时的架构。

初步应用

Ribbon是客户端负载均衡，所以肯定集成再消费端，也就是consumer端

我们修改microservice-student-consumer-80（工程我是在上一篇博客中玩集成建成https://www.cnblogs.com/huangting/p/11902121.html）

首先，引入依赖，pom.xml 加入 ribbon相关依赖

<!--ribbon相关依赖-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-ribbon</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>

给application.yml配置

server:
  port: 80
  context-path: /
eureka:
  client:
    service-url:
      defaultZone: http://eureka2001.ht.com:2001/eureka/,http://eureka2002.ht.com:2002/eureka/,http://eureka2003.ht.com:2003/eureka/
    register-with-eureka: false

ribbon结合eureka来调用服务提供者；

SpringCloudConfig也改成 要加个负载均衡配置 @LoadBalanced

因为和eureka整合，所以启动类StudentConsumerApplication_80 加个注解 @EnableEurekaClient

在提供者microservice-student-provider-1001的yml文件中添加配置：

  application:
    name: microservice-student

上面配置好后，我们可以测试下

先启动三个eureka，然后再启动服务提供者，再启动服务消费者；

访问http://localhost/student/list

---

Ribbon负载均衡

按照它microservice-student-provider-1001建立一个microservice-student-provider子项目，然后将microservice-student-provider-1001这个子项目干掉；

前面搭建了初步例子，但是还没实现真正负载均衡，我们这里要先搞三个服务提供者集群，然后才能演示负载均衡，以及负载均衡策略；

新建项目microservice-student-provider-1002，microservice-student-provider-1003

pom.xml，application.yml，以及java类都复制一份，启动类名称对应的改下；

yml配置文件有两处要对应的改下，port端口改下，以及服务实例名称改下；

pom依赖

<?xml version="1.0" encoding="UTF-8"?>
<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.ht</groupId>
        <artifactId>htSpringCloud</artifactId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <groupId>com.ht</groupId>
    <artifactId>microservice-student-provider</artifactId>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
        </dependency>
        <!--  修改后立即生效，热部署  -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>springloaded</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
        </dependency>

        <!--添加注册中心Eureka相关配置-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>

        <!-- actuator监控引入 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

配置Yml文件

---
server:
  port: 1001
  context-path: /
spring:
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf8
    username: root
    password: root
  jpa:
    hibernate:
      ddl-auto: update
    show-sql: true
  application:
    name: microservice-student
  profiles: provider-1001

eureka:
  instance:
    hostname: localhost
    appname: microservice-student
    instance-id: microservice-student:1001
    prefer-ip-address: true
  client:
    service-url:
      defaultZone: http://eureka2001.ht.com:2001/eureka/,http://eureka2002.ht.com:2002/eureka/,http://eureka2003.ht.com:2003/eureka/

info:
  groupId: com.ht.htSpringCloud
  artifactId: microservice-student-provider-1001
  version: 1.0-SNAPSHOT
  userName: http://ht.com
  phone: 123456

---
server:
  port: 1002
  context-path: /
spring:
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf8
    username: root
    password: root
  jpa:
    hibernate:
      ddl-auto: update
    show-sql: true
  application:
    name: microservice-student
  profiles: provider-1002

eureka:
  instance:
    hostname: localhost
    appname: microservice-student
    instance-id: microservice-student:1002
    prefer-ip-address: true
  client:
    service-url:
      defaultZone: http://eureka2001.ht.com:2001/eureka/,http://eureka2002.ht.com:2002/eureka/,http://eureka2003.ht.com:2003/eureka/

info:
  groupId: com.ht.htSpringCloud
  artifactId: microservice-student-provider-1002
  version: 1.0-SNAPSHOT
  userName: http://ht.com
  phone: 123456

---
server:
  port: 1003
  context-path: /
spring:
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf8
    username: root
    password: root
  jpa:
    hibernate:
      ddl-auto: update
    show-sql: true
  application:
    name: microservice-student
  profiles: provider-1003

eureka:
  instance:
    hostname: localhost
    appname: microservice-student
    instance-id: microservice-student:1003
    prefer-ip-address: true
  client:
    service-url:
      defaultZone: http://eureka2001.ht.com:2001/eureka/,http://eureka2002.ht.com:2002/eureka/,http://eureka2003.ht.com:2003/eureka/

info:
  groupId: com.ht.htSpringCloud
  artifactId: microservice-student-provider-1003
  version: 1.0-SNAPSHOT
  userName: http://ht.com
  phone: 123456

启动类中添加注解

package com.ht.microservicestudentprovider;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.domain.EntityScan;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

@EntityScan("com.ht.*.*")
@EnableEurekaClient
@SpringBootApplication
public class MicroserviceStudentProviderApplication {

    public static void main(String[] args) {
        SpringApplication.run(MicroserviceStudentProviderApplication.class, args);
    }

}

在消费者microservice-student-provider-80的controller中加：

    @RequestMapping("/ribbon")
    public String ribbon(){
        return restTemplate.getForObject(SERVER_IP_PORT+"/student/ribbon/", String.class);
    }

生产者microservice-student-providerd controller中加：

  @Value("${server.port}")
    private String port;

    @RequestMapping("/ribbon")
    public String ribbon(){
        return "工号【"+port+"】正在为您服务";
    }

我们启动服务后在浏览器中刷新地址

每刷新一次后台就会更改一次服务工号

假如有3个服务提供者，突然挂了一个，那么就会产生1/3的概率访问失败； 所以ribbon给我们提供了一个很好的插件。

在microservicestudentconsumer80的

SpringCloudConfig中 加：

/**
     * 自定义调用规则（服务提供者掉线后不再调用，解决轮询问题）
     * @return
     */
    @Bean
    public IRule myRule(){
        return new RetryRule();
//        return new RandomRule();
    }

---

Feign简介及应用

• 简介

　　Feign是一个声明式的Web Service客户端，它使得编写Web Serivce客户端变得更加简单。我们只需要使用Feign来创建一个接口并用注解来配置它既可完成。它具备可插拔的注解支持，包括Feign注解和JAX-RS注解。Feign也支持可插拔的编码器和解码器。Spring Cloud为Feign增加了对Spring MVC注解的支持，还整合了Ribbon和Eureka来提供均衡负载的HTTP客户端实现。

这段话看起来比较懵逼，这里说下实际使用，前面Ribbon调用服务提供者，我们通过restTemplate调用，缺点是，多个地方调用，同一个请求要写多次，不方便统一维护，这时候Feign来了，就直接把请求统一搞一个service作为FeignClient，然后其他调用Controller需要用到的，直接注入service，直接调用service方法即可；同时Feign整合了Ribbon和Eureka，所以要配置负载均衡的话，直接配置Ribbon即可，无其他特殊地方；当然Fiegn也整合了服务容错保护，断路器Hystrix，后面再说。

• 应用

　　在common项目里建一个service（实际项目肯定是多个service）作为Feign客户端，用Feign客户端来调用服务器提供者，当然可以配置负载均衡；Feign客户端定义的目的，就是为了方便给其他项目调用；

修改 microservice-common

pom.xml引入Feign依赖：

<!--引入Feign依赖-->
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-feign</artifactId>
</dependency>

创建StudentClientService接口：

package com.ht.microservicecommon;

import com.ht.microservicecommon.entity.Student;
import org.springframework.cloud.netflix.feign.FeignClient;
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.RequestMapping;

import java.util.List;

/**
 * Student Feign接口客户端
 * @author Administrator
 *
 */
@FeignClient(value="MICROSERVICE-STUDENT")
public interface StudentClientService {

    /**
     * 根据id查询学生信息
     * @param id
     * @return
     */
    @GetMapping(value="/student/get/{id}")
    public Student get(@PathVariable("id") Integer id);

    /**
     * 查询学生信息
     * @return
     */
    @GetMapping(value="/student/list")
    public List<Student> list();

    /**
     * 添加或者修改学生信息
     * @param student
     * @return
     */
    @PostMapping(value="/student/save")
    public boolean save(Student student);

    /**
     * 根据id删除学生信息
     * @return
     */
    @GetMapping(value="/student/delete/{id}")
    public boolean delete(@PathVariable("id") Integer id);

    @RequestMapping("/student/ribbon")
    public String ribbon();
}

　　新建一个Feign消费者项目；

参考microservice-student-consumer-80建一个microservice-student-consumer-feign-80

代码都复制一份，包括pom.xml

新项目中需要添加新pom依赖

  <!--ribbon相关依赖-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-ribbon</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>

        <!--引入Feign依赖-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-feign</artifactId>
        </dependency>
    </dependencies>

SpringCloudconig

package com.ht.microservicestudentconsumerfeign80.config;

import com.netflix.loadbalancer.IRule;
import com.netflix.loadbalancer.RandomRule;
import com.netflix.loadbalancer.RetryRule;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;

@Configuration
public class SpringCloudConfig {
    @LoadBalanced  // 引入ribbon负载均衡
    @Bean
    public RestTemplate getRestTemplate(){
        return new RestTemplate();
    }
    /**
     * 自定义调用规则（服务提供者掉线后不再调用，解决轮询问题）
     * @return
     */
    @Bean
    public IRule myRule(){
        return new RetryRule();
//        return new RandomRule();
    }
}

Yml文件

server:
  port: 80
  context-path: /
eureka:
  client:
    service-url:
      defaultZone: http://eureka2001.ht.com:2001/eureka/,http://eureka2002.ht.com:2002/eureka/,http://eureka2003.ht.com:2003/eureka/
    register-with-eureka: false

启动类中添加注释

package com.ht.microservicestudentconsumerfeign80;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
import org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.netflix.feign.EnableFeignClients;

@EnableEurekaClient
@EnableFeignClients(value = "com.ht.*.*")
@SpringBootApplication(exclude={DataSourceAutoConfiguration.class, HibernateJpaAutoConfiguration.class})
public class MicroserviceStudentConsumerFeign80Application {

    public static void main(String[] args) {
        SpringApplication.run(MicroserviceStudentConsumerFeign80Application.class, args);
    }

}

StudnetConsumerController

package com.javaxl.microservicestudentconsumerfeign80.controller;

import com.ht.microservicecommon.StudentClientService;
import com.ht.microservicecommon.entity.Student;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.client.RestTemplate;

import java.util.List;

@RestController
@RequestMapping("/student")
public class StudentConsumerController {

    @Autowired
    private StudentClientService studentClientService;

    @Autowired
    private RestTemplate restTemplate;

    @PostMapping(value = "/save")
    private boolean save(Student student) {
        return studentClientService.save(student);
    }

    @GetMapping(value = "/list")
    public List<Student> list() {
        return studentClientService.list();
    }

    @GetMapping(value = "/get/{id}")
    public Student get(@PathVariable("id") Integer id) {
        return studentClientService.get(id);
    }

    @GetMapping(value = "/delete/{id}")
    public boolean delete(@PathVariable("id") Integer id) {
        try {
            studentClientService.delete(id);
            return true;
        } catch (Exception e) {
            return false;
        }
    }

    @RequestMapping("/ribbon")
    public String ribbon(){
        return studentClientService.ribbon();
    }
}

因为现在用Fiegn，所以把restTemplate去掉，改成注入service，调用service方法来实现服务的调用；

谢谢观看！！