一，创建服务提供者

创建三个服务提供者分别为8001，8002，8003端口并连接不同的数据库来模拟来自不同的服务器从而实现负载均衡

三个服务提供者实现相同的业务并提供相同的Rest接口

mapper

<mapper namespace="com.yyx.springcloud.dao.DeptDao">
    <insert id="addDept" parameterType="Dept">
    insert into dept(dname,db_source) values(#{dname},DATABASE())
    </insert>
    <select id="queryAll" resultType="Dept">
        select * from dept
    </select>
    <select id="queryById" parameterType="Long" resultType="Dept">
        select * from dept where deptno=#{deptno}
    </select>
</mapper>

controller

@RestController
public class DeptController {
    @Autowired
    private DeptService deptService;
    @PostMapping("/dept")
    public int addDept(@RequestBody Dept dept){
        return deptService.addDept(dept);
    }
    @GetMapping("/dept/{id}")
    public Dept queryById(@PathVariable("id") Long id){
        return deptService.queryById(id);
    }
    @GetMapping("/dept")
    public List<Dept> queryAll(){
        return deptService.queryAll();
    }
}

application.yml
三个服务提供者的配置中application.name和instance-id和所连接的数据库修改为自己对应的

server:
  port: 8001
#mybatis的配置
mybatis:
  type-aliases-package: com.yyx.springcloud.pojo
  mapper-locations: classpath:mapper/*.xml
  configuration:
    map-underscore-to-camel-case: true
#spring的配置
spring:
  application:
    name: SPRINGCLOUD-PROVIDER-DEPT
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/mydb4?useSSL=true&useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC
    username: root
    password: 123456
#eureka的配置
eureka:
  client:
    service-url:
      defaultZone: http://eureka7001.com:7001/eureka/,http://eureka7002.com:7002/eureka/,http://eureka7003.com:7003/eureka/
  instance:
    instance-id: springcloud-provider-dept8001
#info配置
info:
  app.name: springcloud-study
  company.name: yangyongxin.top

所需依赖：(注意服务提供者中需导入eureka依赖)

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
            <version>1.4.6.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>com.yyx</groupId>
            <artifactId>springcloud-api</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
        </dependency>
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-core</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-test</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
        </dependency>
    </dependencies>

二，eureka注册服务

启动类中添加@EnableEurekaServer注解

application.yml中配置(这里做了eureka集群)

server:
  port: 7001

#eureka配置
eureka:
  instance:
    hostname: eureka7001.com #eureka服务端的实例名称
  client:
    register-with-eureka: false #表示是否向eureka注册中心注册自己
    fetch-registry: false #fetch-registry为false，则表示自己为注册中心
    service-url:
      defaultZone: http://eureka7002.com:7002/eureka/,http://eureka7003.com:7003/eureka/

三，服务消费者中设置Ribbon负载均衡

ConfigBean
注入RestTemplate并添加注解LoadBalanced配置负载均衡实现RestTemplate

@Configuration
public class ConfigBean {
    @Bean
    @LoadBalanced//配置负载均衡实现RestTemplate
    public RestTemplate getRestTemplate(){
        return new RestTemplate();
    }
}

controller
Ribbon实现负载均衡时间不应写为服务的某个地址，写为服务的名字，负载均衡随机访问这个服务所有实例地址

@RestController
public class DeptConsumerController {
    @Autowired
    private RestTemplate restTemplate;//提供多种便捷访问远程http服务的方法，简单的RestFul服务模板
    //Ribbon实现负载均衡时间不应写为服务的某个地址，写为服务的名字，负载均衡随机访问这个服务所有地址
    //private static final String REST_URL_PREFIX="http://localhost:8001";
    private static final String REST_URL_PREFIX="http://SPRINGCLOUD-PROVIDER-DEPT";
    @RequestMapping("/consumer/dept/add")
    public int add(Dept dept){
        return restTemplate.postForObject(REST_URL_PREFIX+"/dept",dept,int.class);
    }
    @RequestMapping("/consumer/dept/get/{deptno}")
    public Dept dept(@PathVariable("deptno") Long deptno){
        return restTemplate.getForObject(REST_URL_PREFIX+"/dept/"+deptno,Dept.class);
    }
    @RequestMapping("/consumer/dept/list")
    public List<Dept> dept(){
        return restTemplate.getForObject(REST_URL_PREFIX+"/dept",List.class);
    }
}

application.yml中配置(这里做了eureka集群的配置)

server:
  port: 80
#Eureka配置
eureka:
  client:
    register-with-eureka: false #不向eureka中注册自己
    service-url:
      defaultZone: http://eureka7001.com:7001/eureka/,http://eureka7002.com:7002/eureka/,http://eureka7003.com:7003/eureka/

所需依赖（注意服务消费者中需同时添加eureka和ribbon依赖）

        <dependency>
            <groupId>com.yyx</groupId>
            <artifactId>springcloud-api</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-ribbon</artifactId>
            <version>1.4.6.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
            <version>1.4.6.RELEASE</version>
        </dependency>
    </dependencies>