Ribbon負載均衡和Feign消費者調用服務

Ribbon負載均衡介紹

上篇博文寫了eureka服務的注冊和發現，以及它的叢集，但是關于叢集調用服務提供者并沒有講，也就是當服務提供者其中一個節點挂掉，并沒有介紹怎麼去處理以及避免

Ribbon是Netflix釋出的負載均衡器，它有助于控制HTTP和TCP的用戶端的行為。為Ribbon配置服務提供者位址後，Ribbon就可基于某種負載均衡算法，自動地幫助服務消費者去請求。Ribbon預設為我們提供了很多負載均衡算法，例如輪詢、随機等。當然，我們也可為Ribbon實作自定義的負載均衡算法. 在Spring Cloud中，當Ribbon與Eureka配合使用時，Ribbon可自動從Eureka Server擷取服務提供者位址清單，并基于負載均衡算法，請求其中一個服務提供者執行個體。展示了Ribbon與Eureka配合使用時的架構

用戶端內建Ribbon負載均衡

Ribbon是用戶端負載均衡，是以肯定內建再消費端，也就是consumer端

在用戶端添加pom依賴

<!--ribbon相關依賴-->
        <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>

yml配置

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

SpringCloudConfig 負載均衡配置

package com.xiaoyang.microservicestudentconsumer80.config;

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 {

//    消費者通路生産者代碼（服務a和伺服器b通信）
    @LoadBalanced//引入ribbon負載均衡
    @Bean
    public RestTemplate getRestTemplate(){
        return new RestTemplate();
    }
}

因為和eureka整合，是以啟動類StudentConsumerApplication_80 加個注解 @EnableEurekaClient

package com.xiaoyang.microservicestudentconsumer80;

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;

@EnableEurekaClient
@SpringBootApplication(exclude={DataSourceAutoConfiguration.class, HibernateJpaAutoConfiguration.class})
public class MicroserviceStudentConsumer80Application {

    public static void main(String[] args) {
        SpringApplication.run(MicroserviceStudentConsumer80Application.class, args);
    }

}

這裡還有一個，要修改下StudentConsumerController的PRE_HOST，改成指定的微服務應用名稱；

當然這裡要先在服務提供者microservice-student-provider-1001(或者三合一的服務提供配置中)的application.yml加下配置，指定下應用名稱：

Ribbon負載均衡和Feign消費者調用服務

我們的微服務應用名稱是 microservice-student

是以服務調用者這邊的控制器裡PRE_HOST改成 http://MICROSERVICE-STUDENT即可；

MICROSERVICE-STUDENT為Eureka注冊中心的應用名稱

Ribbon負載均衡和Feign消費者調用服務

前面搭建了初步例子，但是還沒實作真正負載均衡，我們這裡要先搞三個服務提供者叢集，然後才能示範負載均衡，以及負載均衡政策

三合一：

---
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: xiaoyang
    password: 123
  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.xiaoyang.com:2001/eureka/,http://eureka2002.xiaoyang.com:2002/eureka/,http://eureka2003.xiaoyang.com:2003/eureka/

info:
  groupId: com.xiaoyang.testSpringcloud
  artifactId: microservice-student-provider-1001
  version: 1.0-SNAPSHOT
  userName: http://xiaoyang.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: xiaoyang
    password: 123
  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.xiaoyang.com:2001/eureka/,http://eureka2002.xiaoyang.com:2002/eureka/,http://eureka2003.xiaoyang.com:2003/eureka/

info:
  groupId: com.xiaoyang.testSpringcloud
  artifactId: microservice-student-provider-1002
  version: 1.0-SNAPSHOT
  userName: http://xiaoyang.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: xiaoyang
    password: 123
  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.xiaoyang.com:2001/eureka/,http://eureka2002.xiaoyang.com:2002/eureka/,http://eureka2003.xiaoyang.com:2003/eureka/

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

controller

package com.xiaoyang.microservicestudentprovider.controller;

import com.xiaoyang.microservicecommon.entity.Student;
import com.xiaoyang.microservicestudentprovider.service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.*;

import java.util.List;

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

    @Autowired
    private StudentService studentService;


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

    @RequestMapping("/ribbon")
    public String ribbon() {
        return "工号【" + port + "】正在為您服務";
    }

    @PostMapping(value = "/save")
    public boolean save(Student student) {
        try {
            studentService.save(student);
            return true;
        } catch (Exception e) {
            return false;
        }
    }

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

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

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

現在就可以啟動服務進行檢視了

多重新整理幾次看控制台，我們看到有預設的輪詢政策，通路對應的服務提供者（負載均衡會輪詢服務提供者的節點）

但是這種預設的輪詢政策肯定是不能滿足實際需求的，比如有3個服務提供者，突然挂了一個，這樣的話，預設輪詢，總有1/3的機率通路失敗；是以我們看下ribbon預設給我們提供的政策有哪些：

Ribbon負載均衡和Feign消費者調用服務

消費者配置類

/**
     * 自定義調用規則（服務提供者掉線後不再調用，解決輪詢問題）
     * @return
     */
    @Bean
    public IRule myRule(){
        return new RetryRule();
//        return new RandomRule();
    }

我們可以同時啟動三個服務，斷掉一個01服務節點，當負載均衡的輪詢機制重新整理到01時，則不會将報錯資訊顯示，如果沒有配置重試政策機制，則會在通路頁面顯示報錯資訊。當01節點重新啟動服務，輪詢機制會它重新加回輪詢中，此時這個節點又可以通路了…

聲明式服務調用Feign

前面Ribbon調用服務提供者，我們通過restTemplate調用，缺點是，多個地方調用，同一個請求要寫多次，不友善統一維護，這時候Feign來了，就直接把請求統一搞一個service作為FeignClient，然後其他調用Controller需要用到的，直接注入service，直接調用service方法即可；同時Feign整合了Ribbon和Eureka，是以要配置負載均衡的話，直接配置Ribbon即可，無其他特殊地方；當然Fiegn也整合了服務容錯保護，斷路器Hystrix

應用：

在common項目裡建一個service（實際項目肯定是多個service）作為Feign用戶端，用Feign用戶端來調用伺服器提供者，當然可以配置負載均衡；Feign用戶端定義的目的，就是為了友善給其他項目調用

pom.xml引入Feign依賴

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

建StudentClientService接口

package com.xiaoyang.microservicecommon.service;

import com.xiaoyang.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接口用戶端
 * @author Administrator
 *
 */
@FeignClient(value="MICROSERVICE-STUDENT")
public interface StudentClientService {
 
    /**
     * 根據id查詢學生資訊
     * @param id
     * @return
     */
    @GetMapping(value="/student/get/{id}")
    public Student get(@PathVariable("id") Integer id);
     
    /**
     * 查詢學生資訊
     * @return
     */
    @GetMapping(value="/student/list")
    public List<Student> list();
     
    /**
     * 添加或者修改學生資訊
     * @param student
     * @return
     */
    @PostMapping(value="/student/save")
    public boolean save(Student student);
     
    /**
     * 根據id删除學生資訊
     * @return
     */
    @GetMapping(value="/student/delete/{id}")
    public boolean delete(@PathVariable("id") Integer id);

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

microservice-student-consumer-feign-80引入和原microservice-student-consumer–80一樣的配置（多了一個Feign依賴）

<?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.xiaoyang</groupId>
        <artifactId>microservice</artifactId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <artifactId>microservice-student-consumer-feign-80</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>
        <!--  修改後立即生效，熱部署  -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>springloaded</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
        </dependency>
        <!--ribbon相關依賴-->
        <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>
        <dependency>
            <groupId>com.xiaoyang</groupId>
            <artifactId>microservice-common</artifactId>
            <version>1.0-SNAPSHOT</version>
            <scope>compile</scope>
        </dependency>
        <!--引入Feign依賴-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-feign</artifactId>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

啟動類加上注解

controller

package com.xiaoyang.microservicestudentconsumerfeign80.controller;

import com.xiaoyang.microservicecommon.entity.Student;
import com.xiaoyang.microservicecommon.service.StudentClientService;
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();
    }
}

over…

Ribbon負載均衡和Feign消費者調用服務

目錄

Ribbon負載均衡介紹

用戶端內建Ribbon負載均衡

聲明式服務調用Feign

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