详解spring cloud中使用Ribbon实现客户端的软负载均衡

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);   } } 

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;   } } 

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=? 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=? 

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]