前言：微服务架构，不可避免的存在单个微服务有多个实例，那么客户端如何将请求分摊到多个微服务的实例上呢？这里我们就需要使用负载均衡了
一、ribbon简介
ribbon是netflix发布的负载均衡器，它有助于控制http和tcp客户端的行为。为ribbon配置服务提供者地址列表后，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的负载均衡算法，例如：轮询，随机等，也可自定义；
ribbon的github： https://github.com/netflix/ribbon
而在springcloud中使用ribbon和eureka时，ribbon会自动从eurekaserver中获取服务提供者地址列表，并基于负载均衡算法。
二、ribbon实战
1、创建eurekaserver，eurekaclient1，eurekaclient2，之前已经说过了eureka的使用，这里直接上代码：
eurekaserver：
serverapplication.java
|
1
2
3
4
5
6
7
8
9
|
@springbootapplication@enableeurekaserverpublic class serverapplication { public static void main(string[] args) { springapplication.run(serverapplication.class,args); }} |
pom.xml
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
|
<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelversion>4.0.0</modelversion> <groupid>com.cn</groupid> <artifactid>eureka-ribbon-server</artifactid> <version>1.0-snapshot</version> <properties> <project.build.sourceencoding>utf-8</project.build.sourceencoding> <java.version>1.8</java.version> </properties> <parent> <groupid>org.springframework.boot</groupid> <artifactid>spring-boot-starter-parent</artifactid> <version>1.5.13.release</version> </parent> <dependencies> <dependency> <groupid>org.springframework.</groupid> <artifactid></artifactid> </dependency> <dependency> <groupid>org.springframework.cloud</groupid> <artifactid>spring-cloud-starter-eureka-server</artifactid> </dependency> </dependencies> <dependencymanagement> <dependencies> <dependency> <groupid>org.springframework.cloud</groupid> <artifactid>spring-cloud-dependencies</artifactid> <version>edgware.sr3</version> <type>pom</type> <scope>import</scope> </dependency> </dependencies> </dependencymanagement> <!-- 添加spring-boot的maven插件 --> <build> <plugins> <plugin> <groupid>org.springframework.boot</groupid> <artifactid>spring-boot-maven-plugin</artifactid> </plugin> </plugins> </build></project> |
application.properties
|
1
2
3
4
5
6
7
8
|
server.port=8761#注意：这两个配置eureka默认为true，要改成false，否则会报错，connot connect server#表示是否将自己注册在eurekaserver上eureka.client.register-with-eureka=false#表示是否从eurekaserver获取注册信息eureka.client.fetch-registry=falseeureka.client.service-url.defaultzone=http://localhost:8761/eureka/ |
eurekaclient1:
pom.xml
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
|
<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelversion>4.0.0</modelversion> <groupid>com.cn</groupid> <artifactid>eureka-ribbon-client</artifactid> <version>1.0-snapshot</version> <properties> <project.build.sourceencoding>utf-8</project.build.sourceencoding> <java.version>1.8</java.version> </properties> <parent> <groupid>org.springframework.boot</groupid> <artifactid>spring-boot-starter-parent</artifactid> <version>1.5.13.release</version> </parent> <dependencies> <dependency> <groupid>org.springframework.cloud</groupid> <artifactid>spring-cloud-starter-ribbon</artifactid> </dependency> <dependency> <groupid>org.springframework.cloud</groupid> <artifactid>spring-cloud-starter-eureka</artifactid> </dependency> </dependencies> <dependencymanagement> <dependencies> <dependency> <groupid>org.springframework.cloud</groupid> <artifactid>spring-cloud-dependencies</artifactid> <version>edgware.sr3</version> <type>pom</type> <scope>import</scope> </dependency> </dependencies> </dependencymanagement> <!-- 添加spring-boot的maven插件 --> <build> <plugins> <plugin> <groupid>org.springframework.boot</groupid> <artifactid>spring-boot-maven-plugin</artifactid> </plugin> </plugins> </build></project> |
|
1
2
3
|
server.port=8762spring.application.name=client-8762eureka.client.service-url.defaultzone=http://localhost:8761/eureka/ |
而在启动类中加入resttemplate远程调用实例到容器中，并且 添加loadbalanced注解，使resttemplate具备负载均衡的能力 ：
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
|
@springbootapplication@enablediscoveryclientpublic class clientapplication { public static void main(string[] args) { springapplication.run(clientapplication.class, args); } /** * @description: 加入@loadbalanced注解，就可以为resttemplate加入负载均衡的能力 * @param: * @return: * @author: * @date: 2018/6/15 */ @bean @loadbalanced public resttemplate getresttemplate() { return new resttemplate(); }} |
创建controller，注入resttemplate、loadbalancerclient实例：
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
|
package com.cn.controller;import org.springframework.beans.factory.annotation.autowired;import org.springframework.cloud.client.serviceinstance;import org.springframework.cloud.client.loadbalancer.loadbalancerclient;import org.springframework.stereotype.controller;import org.springframework.web.bind.annotation.getmapping;import org.springframework.web.bind.annotation.responsebody;import org.springframework.web.client.resttemplate;/** * @program: springcloud-example * @description: * @author: * @create: 2018-06-15 15:55 **/@controllerpublic class ribboncontroller { @autowired private loadbalancerclient loadbalancerclient; @autowired private resttemplate resttemplate; @getmapping("/loadinstance") @responsebody public string loadinstance() { serviceinstance choose = this.loadbalancerclient.choose("client-87"); system.out.println(choose.getserviceid()+":"+choose.gethost()+":"+choose.getport()); return choose.getserviceid() + ":" + choose.gethost() + ":" + choose.getport(); }} |
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
|
package com.cn;import org.springframework.boot.springapplication;import org.springframework.boot.autoconfigure.springbootapplication;import org.springframework.cloud.client.discovery.enablediscoveryclient;/** * @program: springcloud-example * @description: * @author: 535504 * @create: 2018-06-15 16:05 **/@springbootapplication@enablediscoveryclientpublic class clientapplication { public static void main(string[] args) { springapplication.run(clientapplication.class, args); }} |
eurekaclient2：
pom.xml与eurekaclient1中一致
application.xml:
|
1
2
3
|
server.port=8763spring.application.name=client-87eureka.client.service-url.defaultzone=http://localhost:8761/eureka |
clientcontroller.java:
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
|
package com.cn.contorller;import org.springframework.stereotype.controller;import org.springframework.web.bind.annotation.getmapping;import org.springframework.web.bind.annotation.responsebody;/** * @program: springcloud-example * @description: * @author: * @create: 2018-06-15 16:12 **/@controllerpublic class clientcontroller { @getmapping("/getuser") @responsebody public string getuser() { system.out.println("获取用户成功"); return "获取用户成功"; }} |
2、启动顺序：
①、依次启动eurekaserver =》 eurekaclient1 =》 eurekaclient2 ；
②、然后将eurekaclient2中的application.properties的server.port=8763改为server.port=8764，再次启动该项目;
③、打开eurekaserver的配置页面（http://localhost:8761/），如下：
④、我们在地址栏输入http://localhost:8762/loadinstance，多刷新几次，会发现每次调用的端口实例都不同，如下图：
⑤、我们在看控制台，如图：
至此，ribbon已经入门，是不是很简单，但是这只是最简单的应用，九牛一毛尔...学无止境乎！
示例代码：https://gitee.com/lfalex/springcloud-example
原文链接：http://www.cnblogs.com/lfalex0831/p/9188214.html
