1. 什么是 Spring Cloud?
Spring 提供了一系列工具,可以帮助开发人员迅速搭建分布式系统中的公共组件(比如:配置管理,服务发现,断路器,智能路由,微代理,控制总线,一次性令牌,全局锁,主节点选举, 分布式 session, 集群状态)。协调分布式环境中各个系统,为各类服务提供模板性配置。使用 Spring Cloud, 开发人员可以搭建实现了这些样板的应用,并且在任何分布式环境下都能工作得非常好,小到笔记本电脑, 大到数据中心和云平台。
Spring Cloud 官网的定义比较抽象,我们可以从简单的东西开始。Spring Cloud 是基于 Spring Boot 的, 最适合用于管理 Spring Boot 创建的各个微服务应用。要管理分布式环境下的各个 Spring Boot 微服务,必然存在服务的注册问题。所以我们先从服务的注册谈起。既然是注册,必然有个管理注册中心的服务器,各个在 Spring Cloud 管理下的 Spring Boot 应用就是需要注册的 client
2. 创建 Eureka Server
1).创建一个 Maven 工程 helloworld.eureka.server, 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.chry</groupId> <artifactId>springcloud.helloworld.eureka.server</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>springcloud.helloworld.Eureka.server</name> <description>Demo Spring Eureka Server</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.3.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> <!--eureka server --> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-eureka</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-eureka-server</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-config</artifactId> </dependency> <!-- spring boot test--> <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>Dalston.RC1</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> <snapshots> <enabled>false</enabled> </snapshots> </repository> </repositories> </project>
2). 用 Spring Boot 创建一个服务类 EurekaServerApplication,需要一个注解 @EnableEurekaServer 加在 springboot 工程的启动类上
package springcloud.helloworld.eureka.server;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;
@EnableEurekaServer
@SpringBootApplication
public class EurekaServerApplication {
public static void main(String[] args) {
SpringApplication.run(EurekaServerApplication.class, args);
}
}
3).eureka server 的配置文件 appication.yml,其中 registerWithEureka:false 和 fetchRegistry:false 表明自己是一个 eureka server
server: port: 8761 eureka: instance: hostname: localhost client: registerWithEureka: false fetchRegistry: false serviceUrl: defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/
4) eureka server 的工程结构如下
5)启动 eureka server,然后访问 http://localhost:8761, 界面如下, "No instances available" 表示无 client 注册
3. 创建 Eureka Client
1). 创建一个 Maven 工程 helloworld.eureka.client, 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.chry</groupId> <artifactId>springcloud.helloworld.eureka.client</artifactId> <version>0.0.1-SNAPSHOT</version> <name>springcloud.helloworld.eureka.client</name> <packaging>jar</packaging> <description>Demo Spring Boot Client</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.3.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</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</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>Dalston.RC1</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> <snapshots> <enabled>false</enabled> </snapshots> </repository> </repositories> </project>
2). 创建主类 EurekaClientApplication
使用 @EnableEurekaClient 注解表明是 client
package springcloud.helloworld.eureka.client;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
@SpringBootApplication
@EnableEurekaClient
@RestController
public class EurekaClientApplication {
public static void main(String[] args) {
SpringApplication.run(EurekaClientApplication.class, args);
}
@Value("${server.port}")
String port;
@RequestMapping("/")
public String home() {
return "hello world from port " + port
}
}
3) eureka client 的配置文件 appication.yml
eureka: client: serviceUrl: defaultZone: http://localhost:8761/eureka/ server: port: 8762 spring: application: name: service-helloworld
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