springcloud微服务实战学习笔记三服务消费者-优快云博客

本文介绍了三种实现微服务负载均衡的方法：使用LoadBalancerClient、Ribbon及Feign。通过具体的代码示例展示了如何配置这些组件，并在Spring Cloud环境中实现服务发现和服务调用。

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###第一种方式LoadBalancerClient

依赖

      <parent>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter-parent</artifactId>
          <version>1.5.4.RELEASE</version>
          <relativePath/> <!-- lookup parent from repository -->
      </parent>
      <properties>
          <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
          <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
          <java.version>1.8</java.version>
      </properties>

      <dependencies>
          <dependency>
              <groupId>org.springframework.cloud</groupId>
              <artifactId>spring-cloud-starter-eureka-server</artifactId>
          </dependency>
          <dependency>
              <groupId>org.springframework.boot</groupId>
              <artifactId>spring-boot-starter-web</artifactId>
          </dependency>
      </dependencies>

      <dependencyManagement>
          <dependencies>
              <dependency>
                  <groupId>org.springframework.cloud</groupId>
                  <artifactId>spring-cloud-dependencies</artifactId>
                  <version>Dalston.SR1</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>
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配置文件

  spring.application.name=eureka-consumer
  server.port=3333
  #服务注册中心
  eureka.client.serviceUrl.defaultZone=http://localhost:1111/eureka/
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application

  @EnableDiscoveryClient
  @SpringBootApplication
  public class Application {
  
      @Bean
      public RestTemplate restTemplate() {
          return new RestTemplate();
      }
  
      public static void main(String[] args) {
          new SpringApplicationBuilder(Application.class).web(true).run(args);
      }
  }
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controller

  @RestController
  public class DemoController {
      Logger logger = LoggerFactory.getLogger(this.getClass());
      @Autowired
      LoadBalancerClient loadBalancerClient;
      @Autowired
      RestTemplate restTemplate;
      @GetMapping("/hello")
      public String hello(){
          ServiceInstance serviceInstance = loadBalancerClient.choose("eureka-client");
          logger.info("host:"+serviceInstance.getHost()+"---port:"+serviceInstance.getPort()+"---uri"+serviceInstance.getUri());
          String url = "http://"+serviceInstance.getHost()+":"+serviceInstance.getPort()+"/hello";
          String forObject = restTemplate.getForObject(url, String.class);
  
          return forObject;
      }
  
  }
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###第二种方式Ribbon

依赖在一种方式下添加依赖

          <dependency>
              <groupId>org.springframework.cloud</groupId>
              <artifactId>spring-cloud-starter-ribbon</artifactId>
          </dependency>
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配置文件修改端口号即可修改Application.java,在RestTemplate上添加注解

    @Bean
    @LoadBalanced
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }
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controller修改为

    @GetMapping("/hello2")
    public String hello2(){
        return restTemplate.getForObject("http://eureka-client/hello",String.class);
    }
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###第三种方式Feign

依赖在第一种方式下添加依赖

  <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-feign</artifactId>
  </dependency>
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配置文件修改端口号即可

Application.java添加注解@EnableFeignClients支持Feign客户端

    @EnableFeignClients
    @EnableDiscoveryClient
    @SpringBootApplication
    public class Application {
    
        public static void main(String[] args) {
            new SpringApplicationBuilder(Application.class).web(true).run(args);
        }
    }
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创建一个接口 @FeignClient("eureka-client")设置使用的服务名称

    @FeignClient("eureka-client")
    public interface DemoService {
    
        @GetMapping("/hello")
        String hello();
    }
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controller

    @RestController
    public class DemoController {
    
        Logger logger = LoggerFactory.getLogger(this.getClass());
        @Autowired
        DemoService demoService;
        @GetMapping("/hello")
        public String hello(){
    
            return demoService.hello();
        }
    }
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三种方式可以混合使用，第二种方式因为将RestTemplate对象添加了注解，所以第一种方式就不能直接使用了，只能利用其它方式发送http请求获取数据。