Spring Cloud做负载均衡

1.新建maven工程，点击finish完成

2.在pom.xml文件中加入必要的依赖

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.lemon.test02</groupId>
    <artifactId>Service01</artifactId>
    <version>1.0-SNAPSHOT</version>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.3.RELEASE</version>
        <relativePath/>
    </parent>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
        <spring-cloud.version>Finchley.RELEASE</spring-cloud.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

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

</project>

3.创建服务注册中心server，新建一个module->Spring Initializer->Cloud Discovery->Eureka Server->finish

4.修改src/main/resources/application.properties为application.yml

5.在包下自动产生的MyServerApplication.java文件中添加@EnableEurakeServer，在application.yml文件中添加如下内容

server:
  port: 8801
eureka:
  instance:
    hostname: localhost
  client:
    register-with-eureka: false
    fetch-registry: false
    service-url:
      defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/
spring:
  application:
    name: eurka-server

6.启动工程，打开localhost:8801测试，出现下图，表明server正常工作

7.新建服务的module，名字为my-service，和server构建方式一模一样，然后修改my-service的pom.xml文件中的spring-cloud-starter-netflix-eureka-server为spring-cloud-starter-netflix-eureka-client，按照上文方式修改properties为yml

8.在my-service模块产生的java文件中添加如下内容

package com.example.myservice;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@SpringBootApplication
@EnableEurekaClient
@RestController
public class MyServiceApplication {

	public static void main(String[] args) {
		SpringApplication.run(MyServiceApplication.class, args);
	}
	@Value("${server.port}")
	String port;
	@RequestMapping("/hi")
	public String home(@RequestParam(value = "name",defaultValue = "lemon") String name){
		return "hi"+name+", I am on the port:"+port;
	}
}

在yml文件中添加

server:
  port: 8802
spring:
  application:
    name: service-ribbon
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8801/eureka/

启动程序测试，此时发现，在localhost:8801网页上，出现一个my-service的应用，在应用程序启动处选择Edit Configuration，去掉Single instance only，便可以修改端口号，再次启动一个服务，打开8801端口网页发现有两个服务

9.创建一个消费者module，名称为my-consume,创建方式和my-service一样，也修改文件为client，添加如下内容到yml文件

server:
  port: 8804
spring:
  application:
    name: my-consume
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8801/eureka/

添加如下内容到java文件中

package com.example.myconsume;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.context.annotation.Bean;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
@EnableEurekaClient
@EnableDiscoveryClient //确保可以注册
public class MyConsumeApplication {

	public static void main(String[] args) {
		SpringApplication.run(MyConsumeApplication.class, args);
	}
	@Bean
	@LoadBalanced
	RestTemplate restTemplate() {
		return new RestTemplate();
	}
}

新建一个service文件，添加如下内容

package com.example.myconsume;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.client.RestTemplate;
@Service
public class HelloService {
    @Autowired
    RestTemplate restTemplate;

    public String hiService(String name) {
        return restTemplate.getForObject("http://MY-SERVICE/hi?name="+name,String.class);
    }
}//其中MY-SERVICE是服务的名称，在网页中可以查到

新建一个controller文件，添加如下内容

package com.example.myconsume;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloControler {
    @Autowired
    HelloService helloService;

    @RequestMapping(value = "/hi")
    public String hi(@RequestParam String name){
        return helloService.hiService(name);

    }

}

启动工程，发现在网页中该服务也注册了，如下图

在网页中输入localhost:8804/hi?name=lemon，不断刷新，发现打印出的端口号是改变的，说明进行负载均衡了

参考：https://blog.csdn.net/forezp/article/details/81040946

原文地址：https://www.cnblogs.com/SakerLiu/p/9743577.html