Spring Cloud 源码分析之 Eureka 篇第一章：准备工作

作者：程序员欣宸

2022 年 7 月 04 日
本文字数：6281 字
阅读完需：约 21 分钟

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这里分类和汇总了欣宸的全部原创(含配套源码)：https://github.com/zq2599/blog_demos

大家好，从本章开始我们一起进入 SpringCloud 的源码世界，通过源码分析再结合实战，一起加深对 SpringCloud 体系的认识；

全文概览

本章是为后续的深度学习做准备工作，主要包含以下两部分：

开发三个简单应用，包括：注册中心、服务提供方、服务消费方，后续研究和实战都在这三个应用基础上进行；
下载后续分析研究中用到的源码，包括 SpringCloud 和 Netflix 的，版本和三个简单应用的一致；

版本列表

JDK：1.8；
spring boot：1.5.9.RELEASE；
spring cloud：Edgware.RELEASE；

应用简介

用列表简介本章要开发的三个应用：

实战源码下载

稍后会详细介绍这三个应用的开发和测试步骤，您也可以在 github 下载这三个应用的源码，地址和链接信息如下表所示：

这个 git 项目中有多个文件夹，本章源码分别在 springclouddeepeureka、springclouddeepprovider、springclouddeepconsumer 这三个文件夹下，如下图红框所示：

接下来准备 demo 工程吧，先从 Eureka 开始：

Eureka 应用

基于 maven 创建一个 spring boot 的 web 应用 springclouddeepeureka，pom.xml 内容如下：

<?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">  <modelVersion>4.0.0</modelVersion>
  <groupId>com.bolingcavalry</groupId>  <artifactId>springclouddeepeureka</artifactId>  <version>0.0.1-SNAPSHOT</version>  <packaging>jar</packaging>
  <name>springclouddeepeureka</name>  <description>Demo project for Eureka server</description>
  <parent>    <groupId>org.springframework.boot</groupId>    <artifactId>spring-boot-starter-parent</artifactId>    <version>1.5.9.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-netflix-eureka-server</artifactId>    </dependency>
    <dependency>      <groupId>org.springframework.boot</groupId>      <artifactId>spring-boot-starter-test</artifactId>      <scope>test</scope>    </dependency>  </dependencies>
  <!--spring cloud依赖管理-->  <!-- 引入spring cloud的依赖 -->  <dependencyManagement>    <dependencies>      <dependency>        <groupId>org.springframework.cloud</groupId>        <artifactId>spring-cloud-dependencies</artifactId>        <version>Edgware.RELEASE</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></project>

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resources 目录下创建配置文件 application.yml，内容如下：

server:  port: 8081eureka:  client:    registerWithEureka: false    fetchRegistry: false    serviceUrl:      defaultZone: http://localhost:8081/eureka/

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启动类 SpringclouddeepeurekaApplication.java 中，添加注解**@EnableEurekaServer**：

package com.bolingcavalry.springclouddeepeureka;
import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;
@SpringBootApplication@EnableEurekaServerpublic class SpringclouddeepeurekaApplication {
  public static void main(String[] args) {    SpringApplication.run(SpringclouddeepeurekaApplication.class, args);  }}

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启动应用，浏览器访问 8081 端口，可见 Eureka 页面如下图：

至此，注册中心启动成功；

服务提供者

基于 maven 创建一个 spring boot 的 web 应用 springclouddeepprovider，pom.xml 内容如下：

<?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">  <modelVersion>4.0.0</modelVersion>
  <groupId>com.bolingcavalry</groupId>  <artifactId>springclouddeepprovider</artifactId>  <version>0.0.1-SNAPSHOT</version>  <packaging>jar</packaging>
  <name>springclouddeepprovider</name>  <description>Demo project for Spring Cloud service provider</description>
  <parent>    <groupId>org.springframework.boot</groupId>    <artifactId>spring-boot-starter-parent</artifactId>    <version>1.5.9.RELEASE</version>  </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.boot</groupId>      <artifactId>spring-boot-starter-web</artifactId>    </dependency>
    <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>    </dependency>  </dependencies>
  <dependencyManagement>    <dependencies>      <dependency>        <groupId>org.springframework.cloud</groupId>        <artifactId>spring-cloud-dependencies</artifactId>        <version>Edgware.RELEASE</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></project>

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resources 目录下创建配置文件 application.yml，内容如下：

server:  port: 8082spring:  application:    name: springcloud-deep-providereureka:  client:    serviceUrl:      defaultZone: http://localhost:8081/eureka/  instance:    prefer-ip-address: true

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启动类 SpringclouddeepproviderApplication.java 中，添加注解**@EnableDiscoveryClient**：

package com.bolingcavalry.springclouddeepprovider;
import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
@SpringBootApplication@EnableDiscoveryClientpublic class SpringclouddeepproviderApplication {
  public static void main(String[] args) {    SpringApplication.run(SpringclouddeepproviderApplication.class, args);  }}

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创建一个 Controller 类，用于提供 http 服务：

package com.bolingcavalry.springclouddeepprovider.Controller;
import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.PathVariable;import org.springframework.web.bind.annotation.RestController;
import java.text.SimpleDateFormat;import java.util.Date;
/** * @Description : 提供普通的http服务 * @Author : za2599@gmail.com * @Date : 2018-08-18 18:25 */@RestControllerpublic class HelloService {
    @GetMapping("hello/{name}")    public String hello(@PathVariable String name){        return "Hello " + name + ", " + new SimpleDateFormat("yyyy-MM-dd hh:mm:ss").format(new Date());    }}

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启动应用，浏览器访问路径：http://localhost:8082/hello/123 ，可收到 server 端响应如下图：

此时去刷新 Eureka 的页面，发现服务已经注册成功了，如下图：

至此，服务提供方应用开发完毕，最后一个是服务消费方 springclouddeepconsumer；

服务消费方

基于 maven 创建一个 spring boot 的 web 应用 springclouddeepconsumer，pom.xml 内容如下：

<?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">  <modelVersion>4.0.0</modelVersion>
  <groupId>com.bolingcavalry</groupId>  <artifactId>springclouddeepconsumer</artifactId>  <version>0.0.1-SNAPSHOT</version>  <packaging>jar</packaging>
  <name>springclouddeepconsumer</name>  <description>Demo project for Spring Cloud service consumer</description>
  <parent>    <groupId>org.springframework.boot</groupId>    <artifactId>spring-boot-starter-parent</artifactId>    <version>1.5.9.RELEASE</version>  </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.boot</groupId>      <artifactId>spring-boot-starter-web</artifactId>    </dependency>
    <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>    </dependency>  </dependencies>
  <build>    <plugins>      <plugin>        <groupId>org.springframework.boot</groupId>        <artifactId>spring-boot-maven-plugin</artifactId>      </plugin>    </plugins>  </build>  </project>

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resources 目录下创建配置文件 application.yml，内容如下：

server:  port: 8083spring:  application:    name: springcloud-deep-consumereureka:  client:    serviceUrl:      defaultZone: http://localhost:8081/eureka/  instance:    prefer-ip-address: true

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启动类 SpringclouddeepconsumerApplication.java 中，添加注解**@EnableDiscoveryClient**：

package com.bolingcavalry.springclouddeepconsumer;
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.context.annotation.Bean;import org.springframework.web.client.RestTemplate;
@SpringBootApplication@EnableDiscoveryClientpublic class SpringclouddeepconsumerApplication {
  @Bean  @LoadBalanced  public RestTemplate restTemplate() {    return new RestTemplate();  }
  public static void main(String[] args) {    SpringApplication.run(SpringclouddeepconsumerApplication.class, args);  }}

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创建一个 Controller 类，用于提供 http 服务：

package com.bolingcavalry.springclouddeepconsumer.controller;
import org.springframework.beans.factory.annotation.Autowired;import org.springframework.cloud.client.ServiceInstance;import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;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;
/** * @Description : 远程调用测试的 * @Author : qin_zhao@kingdee.com * @Date : 2018-08-18 19:10 */@RestControllerpublic class ConsumerServiceController {
    @Autowired    private RestTemplate restTemplate;
    @Autowired    private LoadBalancerClient loadBalancerClient;
    @GetMapping("serviceinfo")    public String serviceinfo(){        ServiceInstance serviceInstance = loadBalancerClient.choose("springcloud-deep-provider");        return null==serviceInstance ? "service not found" : serviceInstance.toString();    }
    @GetMapping("consume/{name}")    public String consume(@PathVariable String name){               return this.restTemplate.getForObject("http://springcloud-deep-provider/hello/" + name, String.class);    }}