Spring Cloud 入门教程(一): 服务注册

系统管理员 2022-04-10 14:22 194阅读 0赞

**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

Spring Cloud使用erureka server,  然后所有需要访问配置文件的应用都作为一个erureka client注册上去。eureka是一个高可用的组件，它没有后端缓存，每一个实例注册之后需要向注册中心发送心跳，在默认情况下erureka server也是一个eureka client ,必须要指定一个 server。

**2.  创建Eureka Server**

1）.创建一个Maven工程springcloud.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>
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.1.1.RELEASE</version>
            <relativePath /> 
        </parent>
        <groupId>springcloud.server</groupId>
        <artifactId>eurekaserver</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <name>eurekaserver</name>
        <description>Demo project for Spring Boot</description>
    
        <properties>
            <java.version>1.8</java.version>
            <spring-cloud.version>Greenwich.RC2</spring-cloud.version>
        </properties>
    
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
            </dependency>
            <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>
    
        <repositories>
            <repository>
                <id>spring-milestones</id>
                <name>Spring Milestones</name>
                <url>https://repo.spring.io/milestone</url>
            </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.eureka.eurekaserver;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;
    
    @SpringBootApplication
    @EnableEurekaServer
    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

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZmemhpaHVh_size_16_color_FFFFFF_t_70][]

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

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZmemhpaHVh_size_16_color_FFFFFF_t_70 1][]

**3.  创建Eureka Client**

1). 创建一个Maven工程springcloud.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>
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.1.1.RELEASE</version>
            <relativePath /> 
        </parent>
        <groupId>springcloud.client</groupId>
        <artifactId>eurekaclient</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <name>eurekaclient</name>
        <description>Demo project for Spring Boot</description>
    
        <properties>
            <java.version>1.8</java.version>
            <spring-cloud.version>Greenwich.RC2</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>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </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>

2).  创建主类EurekaClientApplication

使用@EnableEurekaClient注解表明是client

package springcloud.client.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.RequestMethod;
    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(value = "/",method = RequestMethod.GET)
        public String home() {
            return "hell word  this 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

4). Client启动后， 可以访问http://localhost:8762

![20190111151554139.png][]

5). 再次访问服务器端口, 可以看到Service Helloworld已经自动注册到之前的server中

** **![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZmemhpaHVh_size_16_color_FFFFFF_t_70 2][]

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[20190111151554139.png]: /images/20220328/e4a8c41ece2c455997f407a0db4a3e26.png
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