使用IDEA新建MAVEN的多模块项目
Spring Cloud的环境配置：
JDK/SDK：1.8.0_212
Maven version: 3.5.0
spring-boot.version：2.1.6.RELEASE
spring-cloud.version：Greenwich.RELEASE
[TOC]
一、Spring Cloud和Spring Boot的版本
注意: 截至到今天（2019/08/02），各个版本的对应情况：
| Release Train | Boot Version |
|---|---|
| Greenwich | 2.1.x |
| Finchley | 2.0.x |
| Edgware | 1.5.x |
| Dalston | 1.5.x |
请注意Spring Cloud的overview里的这段话：
Finchley builds and works with Spring Boot 2.0.x, and is not expected to work with Spring Boot 1.5.x.
Note: The Dalston release train will reach end-of-life in December 2018. Edgware will follow the end-of-life cycle of Spring Boot 1.5.x.
The Dalston and Edgware release trains build on Spring Boot 1.5.x, and are not expected to work with Spring Boot 2.0.x.
以上内容摘自：https://spring.io/projects/spring-cloud#overview
二、创建服务注册和发现中心
Spring Cloud Netflix项目提供的集成有：
服务发现（Eureka）
断路器（Hystrix）
智能路由（Zuul）
客户端负载平衡（Ribbon）
2.1、创建服务的父级工程
我使用的是Eureka，之前我也用过Consul，先说一下Eureka吧。
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注意Type的时候选择Maven POM，然后一路next就可以了。修改pom文件如下：
<?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>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.6.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.ac</groupId>
<artifactId>echo-parent</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>pom</packaging>
<name>echo-parent</name>
<description>Demo project for Spring Boot</description>
<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.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>${spring-cloud.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
2.2、创建子项目Eureka Service和Eureka Client
在echo-parent的项目上右键-->>New-->>Module，选择Spring Initializr，选择合适的GAV属性标签，这里的Type选择Maven Project，然后添加eureka对应的起步依赖即可。
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修改eureka-service的pom文件如下：
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.ac</groupId>
<artifactId>echo-parent</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<groupId>com.ac</groupId>
<artifactId>eureka-service</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>eureka-service</name>
<description>Demo project for Spring Boot</description>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
在父级pom中添加eureka的module如下：
<modules>
<module>eureka-service</module>
</modules>
在spring boot的启动类EurekaServiceApplication上添加eureka的注释@EnableEurekaServer：
@SpringBootApplication
@EnableEurekaServer
public class EurekaServiceApplication {
public static void main(String[] args) {
SpringApplication.run(EurekaServiceApplication.class, args);
}
}
配置文件采用yml格式：
spring:
application:
name: eurka-server
server:
port: 8761
eureka:
instance:
hostname: localhost
client:
registerWithEureka: false
fetchRegistry: false
serviceUrl:
defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/
在yaml文件中的registerWithEureka和fetchRegistry设置成false，表明当前是eureka的服务器端。在浏览器的地址栏输入http://localhost:8761即可以看到eureka的界面了：
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接下来创建eureka的client项目，创建过程同eureka server差不多，选择的starter是客户端：
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修改pom文件如下：
<?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>
<parent>
<groupId>com.ac</groupId>
<artifactId>echo-parent</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<groupId>com.ac</groupId>
<artifactId>eureka-client</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>eureka-client</name>
<description>Demo project for Spring Boot</description>
<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>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
application.yml文件如下：
spring:
application:
name: eureka-client
server:
port: 8762
eureka:
client:
serviceUrl:
defaultZone: http://localhost:8761/eureka/
eureka-client的启动类如下：
@SpringBootApplication
@EnableEurekaClient
@RestController
public class EurekaClientApplication {
@RequestMapping("/")
public String home() {
return "Hello world";
}
public static void main(String[] args) {
SpringApplication.run(EurekaClientApplication.class, args);
}
}
启动eureka-service和eureka-client，打开http://localhost:8761/就可以看到实例已经注册上去了，服务名称是eureka-client，端口号是8762：
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打开http://localhost:8762/，可以看到我们的hello world。
注意：现在在eureka-client可以不用输入注释@EnableEurekaClient就可以开启eureka的客户端支持！！！以下是spring cloud官方提供的说明，请注意：只要在classpath中引用了spring-cloud-starter-netflix-eureka-client的GAV就可以开始eureka的支持了，至于原理需要看一下源码才能分析出来。
The following example shows a minimal Eureka client application:
@SpringBootApplication @RestController public class Application { @RequestMapping("/") public String home() { return "Hello world"; } public static void main(String[] args) { new SpringApplicationBuilder(Application.class).web(true).run(args); } }Note that the preceding example shows a normal Spring Boot application. By having
spring-cloud-starter-netflix-eureka-clienton the classpath, your application automatically registers with the Eureka Server. Configuration is required to locate the Eureka server, as shown in the following example: ... ...
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