RestTemplate对象与LoadBalanced注解

Posted 2023-02-23 旺仔哥

RestTemplate介绍

• RestTemplate是Spring Cloud访问Restful API的请求对象
• RestTemplate与HttpClient、OKHttp职能类似

@LoadBalanced注解

• @LoadBalanced是Ribbon提供的客户端负载均衡注解
• 通常RestTemplate与@LoadBalanced联合使用

创建订单服务

Spring Initializr 

web->Spring Web

Spring Cloud Discovery -> Eureka Discover Client

Spring Cloud Routing -> Ribbon

 

确保pom.xml引入ribbon

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
        </dependency>

 appliaction.yml

spring:
  application:
    name: member-service
eureka:
  client:
    service-url:
      defaultZone:
        http://localhost:8761/eureka

入口类注入RestTemplate

@SpringBootApplication
@EnableEurekaClient
public class MemberServiceApplication 
    @Bean //注入
    @LoadBalanced //Ribbon负载均衡,默认轮询
    public RestTemplate restTemplate()
        return new RestTemplate();
    

业务开发,服务间通信

@Controller
public class MemberController 
    @Resource
    private RestTemplate restTemplate;

    @GetMapping("/borrow")
    @ResponseBody
    public String borrow(String sn)
        /*
            RestTemplate负载均衡格式要求：
            http://微服务id/webapi地址
        */
        Book book = restTemplate.getForObject("http://book-service/bsn?sn=" + sn, Book.class);
        return book.getName() + ":" + book.getDesc() + "图书借阅成功";
    

业务实体Book与JSON属性对应即可

public class Book 
    private String sn;
    private String name;
    private String desc;

    public String getSn() 
        return sn;
    

    public void setSn(String sn) 
        this.sn = sn;
    

    public String getName() 
        return name;
    

    public void setName(String name) 
        this.name = name;
    

    public String getDesc() 
        return desc;
    

    public void setDesc(String desc) 
        this.desc = desc;