轻松掌握SpringCloud：第一篇：服务注册和发现

梦里梦外; 2022-05-18 02:20 187阅读 0赞

今天我们正式来研究微服务框架SpringCloud，听起来就是不一样的感觉，SpringCloud为开发人员提供了快速构建分布式系统的一些工具，包括配置管理、服务发现、断路器、路由、微代理、事件总线、全局锁、决策竞选、分布式会话等等。

注意啦，如果要掌握SpringCloud，SpringBoot学习必不可少：[轻松搞定SpringBoot][SpringBoot]

其中Eureka组件是一个注册和发现模块，让我们来一睹真颜：

我们需要创建两个SpringBoot应用，一个是server，一个是client

================================创建server===============================

右键工程->创建model-> 选择spring initialir

![70][]

![70 1][]

选择Cloud Discovery -> Eureka Server

![70 2][]

之后的目录结构如下，我们把application.…改为application.yml

![70 3][]

其中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.example</groupId>
        <artifactId>eureka-server</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <packaging>jar</packaging>
    
        <name>eureka-server</name>
        <description>Demo project for Spring Boot</description>
    
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.0.3.RELEASE</version>
            <relativePath/> 
        </parent>
    
        <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>Finchley.RELEASE</spring-cloud.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>
    
        <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>

EurekaServerApplication.java添加注解@EnableEurekaServer，代码如下

package com.example.eurekaserver;
    
    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);
        }
    }

application.yml内容如下

server:
      port: 8765
    
    eureka:
      instance:
        hostname: localhost
      client:
        registerWithEureka: false
        fetchRegistry: false
        serviceUrl:
          defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/

启动服务，浏览器输入localhost:8765，看到的页面如下，我们看到页面左下角，显示No instances available，说明还没有发现注册，至此服务端就开发完成。

![70 4][]

================================创建client===============================

我们重新打开一个idea窗口创建新工程，创建方式和创建server是一样的

代码如下

pom.xml

<?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.example</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>
    
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.0.3.RELEASE</version>
            <relativePath/> 
        </parent>
    
        <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>Finchley.RELEASE</spring-cloud.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>
    
        <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>

EurekaClientApplication.java添加新注解@EnableEurekaClient，代码如下

package com.example.eurekaclient;
    
    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("/hi")
        public String home(@RequestParam String name) {
            return "hi "+name+",i am from port:" +port;
        }
    }

application.yml内容如下

eureka:
      client:
        serviceUrl:
          defaultZone: http://localhost:8765/eureka/
    server:
      port: 8766
    spring:
      application:
        name: service-hi

通过配置文件我们就看到了，其中配置了服务端的ip和端口

启动服务，我们再去服务端的页面看一下，还是熟悉的位置，还是那个老地方，我们看到了一个客户端，你没有看错，这就是刚才我们启动的端口号为8766的客户端服务

![70 5][]

我们再从浏览器输入localhost:8766/hi?name=aaa，页面ok

![70 6][]

到这，简单的发现注册就成功了

有人会问了，这是一个服务，那如果要现实负载均衡怎么办，不急，下篇文章会深入讲解

[SpringBoot]: https://blog.csdn.net/stronglyh/article/details/81236116
[70]: /images/20220518/13ff98b00fde4f049847da40300ced5d.png
[70 1]: /images/20220518/fe9b85603598451992773273c80abd05.png
[70 2]: /images/20220518/1f939a274f194913ac4fd763b6127b3d.png
[70 3]: /images/20220518/6357ffdecc00499089f8cfde49626499.png
[70 4]: /images/20220518/fe4b9f050308450ba6bb3e065f35f600.png
[70 5]: /images/20220518/83791bcb4f3341dba68e556c7b9cff0c.png
[70 6]: /images/20220518/33ab24709e93472380e527321f3d4181.png