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详解spring cloud中使用Ribbon实现客户端的软负载均衡

时间:2021-03-22 13:55     来源/作者:牛奋lch

开篇

本例是在springboot整合h2内存数据库,实现单元测试与数据库无关性使用resttemplate消费spring boot的restful服务两个示例的基础上改造而来

在使用resttemplate来消费spring boot的restful服务示例中,我们提到,调用spring boot服务的时候,需要将服务的url写死或者是写在配置文件中,但这两种方式,无论哪一种,一旦ip地址发生了变化,都需要改动程序,并重新部署服务,使用ribbon的时候,可以有效的避免这个问题。

前言:

负载均衡的实现方式有两种,分别是服务端的负载均衡和客户端的负载均衡

服务端负载均衡:当浏览器向后台发出请求的时候,会首先向反向代理服务器发送请求,反向代理服务器会根据客户端部署的ip:port映射表以及负载均衡策略,来决定向哪台服务器发送请求,一般会使用到nginx反向代理技术。

客户端负载均衡:当浏览器向后台发出请求的时候,客户端会向服务注册器(例如:eureka server),拉取注册到服务器的可用服务信息,然后根据负载均衡策略,直接命中哪台服务器发送请求。这整个过程都是在客户端完成的,并不需要反向代理服务器的参与。

一、启动eureka server

请参考该例:spring cloud中启动eureka server

二、启动微服务,并注册到eureka server上

spring cloud-将spring boot服务注册到eureka server上

为了演示负载均衡的效果,再启动一个为服务,注意需要将端口号改成不一致

三、添加ribbon支持

1、添加ribbon的依赖

详解spring cloud中使用Ribbon实现客户端的软负载均衡

2、添加负载均衡支持

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package com.chhliu.springboot.restful;
import org.springframework.beans.factory.annotation.autowired;
import org.springframework.boot.springapplication;
import org.springframework.boot.autoconfigure.springbootapplication;
import org.springframework.boot.web.client.resttemplatebuilder;
import org.springframework.cloud.client.loadbalancer.loadbalanced;
import org.springframework.cloud.netflix.eureka.enableeurekaclient;
import org.springframework.context.annotation.bean;
import org.springframework.web.client.resttemplate;
@springbootapplication
@enableeurekaclient
public class springbootresttemplateapplication {
   
  @autowired
  private resttemplatebuilder builder;
 
  @bean
  @loadbalanced // 添加负载均衡支持,很简单,只需要在resttemplate上添加@loadbalanced注解,那么resttemplate即具有负载均衡的功能,如果不加@loadbalanced注解的话,会报java.net.unknownhostexception:springboot-h2异常,此时无法通过注册到eureka server上的服务名来调用服务,因为resttemplate是无法从服务名映射到ip:port的,映射的功能是由loadbalancerclient来实现的。
  public resttemplate resttemplate() {
    return builder.build();
  }
 
  public static void main(string[] args) {
    springapplication.run(springbootresttemplateapplication.class, args);
  }
}

3、修改调用微服务的url

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package com.chhliu.springboot.restful.controller;
import org.springframework.beans.factory.annotation.autowired;
import org.springframework.web.bind.annotation.getmapping;
import org.springframework.web.bind.annotation.pathvariable;
import org.springframework.web.bind.annotation.restcontroller;
import org.springframework.web.client.resttemplate; 
import com.chhliu.springboot.restful.vo.user;
 
@restcontroller
public class resttemplatecontroller {
  @autowired
  private resttemplate resttemplate;
   
  @getmapping("/template/{id}")
  public user findbyid(@pathvariable long id) {// 将原来的ip:port的形式,改成注册到eureka server上的应用名即可
    user u = this.resttemplate.getforobject("http://springboot-h2/user/" + id, user.class);
    system.out.println(u);
    return u;
  }
}

四、查看eureka server状态

详解spring cloud中使用Ribbon实现客户端的软负载均衡

五,在浏览器中,多次刷新http://localhost:7904/template/2地址

六、测试结果

7900端口服务:

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hibernate: select user0_.id as id1_0_0_, user0_.age as age2_0_0_, user0_.balance as balance3_0_0_, user0_.name as name4_0_0_, user0_.username as username5_0_0_ from user user0_ where user0_.id=?
hibernate: select user0_.id as id1_0_0_, user0_.age as age2_0_0_, user0_.balance as balance3_0_0_, user0_.name as name4_0_0_, user0_.username as username5_0_0_ from user user0_ where user0_.id=?
hibernate: select user0_.id as id1_0_0_, user0_.age as age2_0_0_, user0_.balance as balance3_0_0_, user0_.name as name4_0_0_, user0_.username as username5_0_0_ from user user0_ where user0_.id=?
hibernate: select user0_.id as id1_0_0_, user0_.age as age2_0_0_, user0_.balance as balance3_0_0_, user0_.name as name4_0_0_, user0_.username as username5_0_0_ from user user0_ where user0_.id=?

7901端口服务:

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hibernate: select user0_.id as id1_0_0_, user0_.age as age2_0_0_, user0_.balance as balance3_0_0_, user0_.name as name4_0_0_, user0_.username as username5_0_0_ from user user0_ where user0_.id=?
hibernate: select user0_.id as id1_0_0_, user0_.age as age2_0_0_, user0_.balance as balance3_0_0_, user0_.name as name4_0_0_, user0_.username as username5_0_0_ from user user0_ where user0_.id=?
hibernate: select user0_.id as id1_0_0_, user0_.age as age2_0_0_, user0_.balance as balance3_0_0_, user0_.name as name4_0_0_, user0_.username as username5_0_0_ from user user0_ where user0_.id=?
hibernate: select user0_.id as id1_0_0_, user0_.age as age2_0_0_, user0_.balance as balance3_0_0_, user0_.name as name4_0_0_, user0_.username as username5_0_0_ from user user0_ where user0_.id=?
hibernate: select user0_.id as id1_0_0_, user0_.age as age2_0_0_, user0_.balance as balance3_0_0_, user0_.name as name4_0_0_, user0_.username as username5_0_0_ from user user0_ where user0_.id=?

7904端口服务:

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user [id=2, username=user2, name=李四, age=20, balance=100.00]
2017-01-23 09:58:05.682 info 7436 --- [erlistupdater-0] c.netflix.config.chaineddynamicproperty : flipping property: springboot-h2.ribbon.activeconnectionslimit to use next property: niws.loadbalancer.availabilityfilteringrule.activeconnectionslimit = 2147483647
user [id=2, username=user2, name=李四, age=20, balance=100.00]
user [id=2, username=user2, name=李四, age=20, balance=100.00]
user [id=2, username=user2, name=李四, age=20, balance=100.00]
user [id=2, username=user2, name=李四, age=20, balance=100.00]
user [id=2, username=user2, name=李四, age=20, balance=100.00]
user [id=2, username=user2, name=李四, age=20, balance=100.00]
user [id=2, username=user2, name=李四, age=20, balance=100.00]
user [id=2, username=user2, name=李四, age=20, balance=100.00]

从上面的测试结果可以看出,总共调了7904端口服务9次,其中7904端口服务调7900端口服务4次,调7901端口5次,刚好是9次

经过上面的几个步骤,就基本使用ribbon实现了客户端负载均衡的功能

以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持服务器之家。

原文链接:http://blog.csdn.net/liuchuanhong1/article/details/54691566

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