Spring Cloud（二）：Spring Cloud服务的注册与发现

我会带着你远行 2022-03-28 18:24 210阅读 0赞

服务的注册与发现：

这里用到了Spring cloud netflix 的eureka服务注册与发现模块。这里什么是Spring Cloud Netflix以后再说！//TODO

建一个springcloud项目：eureka-server，这是服务注册中心，所有服务都要在这里注册，所有的其他客户端调用都是从服务中心来找到需要的服务然后调用。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3c4OTM5MzI3NDc_size_16_color_FFFFFF_t_70][]

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>
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.1.1.RELEASE</version>
            <relativePath/> 
        </parent>
        <groupId>top.wj.springclouod</groupId>
        <artifactId>springcloud</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <name>springcloud</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-server</artifactId>
                <version>2.0.2.RELEASE</version>
            </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>

Application.yml：

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（因此可以在内存中完成），在默认情况下erureka server也是一个eureka client ，，通过eureka.client.registerWithEureka：false和fetchRegistry：false来表明自己是一个eureka serve

server:
      port: 8761
    
    eureka:
      instance:
        hostname: localhost
      client:
        # false和fetchRegistry：false来表明自己是一个eureka server
        registerWithEureka: false
        fetchRegistry: false
        serviceUrl:
          defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/

**启动一个服务注册中心**，只需要一个注解@EnableEurekaServer，这个注解需要在springboot工程的启动application类上加

serviceCenterApplication.java

package top.wj.springclouod;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;
    
    
    @EnableEurekaServer
    @SpringBootApplication
    public class SpringcloudApplication {
    
        public static void main(String[] args) {
            SpringApplication.run(SpringcloudApplication.class, args);
        }
    
    }

启动注册中心：在浏览器中访问localhost：8761:

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3c4OTM5MzI3NDc_size_16_color_FFFFFF_t_70 1][]

在创建一个客户端：client-server，然后在服务的注册中心注册一下，其他的客户端就可以能过服务注册中心发现这个服务，并且调用它

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3c4OTM5MzI3NDc_size_16_color_FFFFFF_t_70 2][]

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>
    	<parent>
    		<groupId>org.springframework.boot</groupId>
    		<artifactId>spring-boot-starter-parent</artifactId>
    		<version>2.1.1.RELEASE</version>
    		<relativePath/> 
    	</parent>
    	<groupId>top.wj.client</groupId>
    	<artifactId>client-server</artifactId>
    	<version>0.0.1-SNAPSHOT</version>
    	<name>client-server</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-server</artifactId>
    			<version>2.0.2.RELEASE</version>
    		</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-autoconfigure</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>

Application.yml:

eureka:
      client:
        serviceUrl:
          defaultZone: http://localhost:8761/eureka/
    server:
      port: 8762
    spring:
      application:
        name: client-service

ClientServericeApplication:

package top.wj.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 ClientServerApplication {
    
    	public static void main(String[] args) {
    		SpringApplication.run(ClientServerApplication.class, args);
    	}
    
    	@Value("${server.port}")
    	String port;
    
    	@Value("${spring.application.name}")
    	String hostName;
    
    	@RequestMapping("/hi")
    	public String home(@RequestParam String name) {
    		return "hi " + name + ",i am from port:" +hostName+":"+ port;
    
    	}
    
    }

启动客户端：在浏览器中访问

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3c4OTM5MzI3NDc_size_16_color_FFFFFF_t_70 3][]

这时刷新注册中心页面：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3c4OTM5MzI3NDc_size_16_color_FFFFFF_t_70 4][]

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