SpringCloud-基于SpringBoot 2.1.3.RELEASE版本从零搭建分布式框架之服务消费者(四)
maven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">
<parent>
<artifactId>spring-cloud</artifactId>
<groupId>com.spring.cloud</groupId>
<version>1.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>eureka-client</artifactId>
<version>1.0-SNAPSHOT</version>
<name>eureka-client</name>
<description>客户端</description>
<packaging>jar</packaging>
<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>Greenwich.RELEASE</spring-cloud.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.mockito</groupId>
<artifactId>mockito-core</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>com.spring.cloud</groupId>
<artifactId>model</artifactId>
<version>1.0-SNAPSHOT</version>
</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>
<repositories>
<repository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
</repository>
</repositories>
</project>
properties 配置
spring.application.name=CONSUME-SERVICE
server.port=9001
eureka.client.serviceUrl.defaultZone= \
http://localhost:8001/eureka/
EurekaClientApplication 启动类编写
package com.spring.cloud.eureka;
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.client.RestTemplate;
/**
* @ClassName EurekaClientApplication
* @Description TODO
* @Author cuixhao
* @Date 2019/3/7
* @Version 1.0
**/
@SpringBootApplication
@EnableEurekaClient
@EnableDiscoveryClient
public class EurekaClientApplication {
@Bean
@LoadBalanced
RestTemplate restTemplate () {
return new RestTemplate();
}
public static void main(String[] args) {
SpringApplication.run(EurekaClientApplication.class, args);
}
}
编写一个调用服务的rest接口
package com.spring.cloud.eureka.controller;
import com.spring.cloud.model.UserVo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;
/**
* @ClassName ConsumeController
* @Description TODO
* @Author cuixhao
* @Date 2019/3/7
* @Version 1.0
**/
@RestController
public class ConsumeController {
@Autowired
RestTemplate restTemplate;
@GetMapping("/add")
public UserVo query(String userId) {
// 通过注册中心找到PRODUCER-SERVICE的服务,服务端已经做负载均衡
return restTemplate.getForObject("http://PRODUCER-SERVICE/add?userId=" + userId, UserVo.class);
}
}
分布式中消费者和生产者概念
分布式中模块都是以Rest接口的形式对外提供服务,生产者和消费者并没有严格的界限区分。两者是服务提供者,假如一个模块调用了另一个模块的服务接口,那么可以称为前者为服务消费者,后者服务生产者。本质上来说,他们都是服务提供者。
此例是消费者通过restTemplate调用注册中心上服务名称为PRODUCER-SERVICE的add的接口,如果PRODUCER-SERVICE是多实例的,那么服务注册中心就会负载均衡到其中一台上提供服务。Client端也提供了如下的代码,其实这也是一个服务,只是相对PRODUCER-SERVICE来说是消费者而已。Client也可以部署多实例提供负载均衡的能力。集群部署参考前几篇中讲到的步骤。
@Bean
@LoadBalanced
RestTemplate restTemplate () {
return new RestTemplate();
}
客户端调用服务的方式
此例是通过ribbon的方式,也就是使用restTemplate,通过http接口的方式调用,
SpringCloud还提供一种Feign的方式调用,这种方式的操作类似于我们写的service模块的接口方式调用,更为便捷,但同时也增加的服务端的代码量。