SpringCloud——服务的注册与发现Eureka

你的名字 2021-05-12 11:55 644阅读 0赞

### 一、spring cloud简介 ###

Spring Cloud为开发人员提供了快速构建分布式系统中一些常见模式的工具（例如配置管理，服务发现，断路器，智能路由，微代理，控制总线）。分布式系统的协调导致了样板模式, 使用Spring Cloud开发人员可以快速地支持实现这些模式的服务和应用程序。他们将在任何分布式环境中运行良好，包括开发人员自己的笔记本电脑，裸机数据中心，以及Cloud Foundry等托管平台。

## 特性 ##

Spring Cloud专注于提供良好的开箱即用经验的典型用例和可扩展性机制覆盖。

*  分布式/版本化配置
 *  服务注册和发现
 *  路由
 *  service - to - service调用
 *  负载均衡
 *  断路器
 *  分布式消息传递

### 二、 创建服务注册中心（eureka-server） ###

是采用Eureka作为服务注册与发现的组件

**1 、首先创建一个maven主工程**

首先创建一个主Maven工程，在其pom文件引入依赖，spring Boot版本为2.0.4.RELEASE，Spring Cloud版本为Finchley.RELEASE。

父pom.xml 文件：

<?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.demo</groupId>
    	<artifactId>springcloud-eureka</artifactId>
    	<version>0.0.1-SNAPSHOT</version>
    	<packaging>pom</packaging>
    
    	<name>springcloud-eureka</name>
    	<description>Demo project for Spring Boot</description>
    
    	<modules>
    		<module>eureka-server</module>
    		<module>eureka-client</module>
    	</modules>
    
    	<parent>
    		<groupId>com.example</groupId>
    		<artifactId>springcloud-master</artifactId>
    		<version>0.0.1-SNAPSHOT</version>
    	</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.boot</groupId>
    			<artifactId>spring-boot-starter</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>

**2 、创建两个model工程，分别为eureka-server和eureka-cient:**

2.1、eureka-server的pom.xml文件：

<?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.demo.eureka</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>com.example.demo</groupId>
    		<artifactId>springcloud-eureka</artifactId>
    		<version>0.0.1-SNAPSHOT</version>
    	</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.boot</groupId>
    			<artifactId>spring-boot-starter</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>
    
    	<build>
    		<plugins>
    			<plugin>
    				<groupId>org.springframework.boot</groupId>
    				<artifactId>spring-boot-maven-plugin</artifactId>
    			</plugin>
    		</plugins>
    	</build>
    
    
    </project>

2.2、注册中心启动类，添加注解@EnableEurekaServer，表明自己是一个eurekaserver.

package com.example.demo.eureka;
    
    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);
    	}
    }

2.3、eureka是没有后端缓存的，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 ,所以必须要指定一个 server。

eureka-server的配置文件appication.yml：

server:
      port: 8081
    
    eureka:
      instance:
        hostname: localhost
      client:
          fetch-registry: false
          register-with-eureka: false
          serviceUrl:
                  defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/
    
    spring:
      application:
        name: eureka-server

注意：通过eureka.client.fetch-registry: false:false和eureka.client.fetch-registry:false来表明自己是一个eureka server.

2.4、 启动工程,打开浏览器访问，[http://localhost:8][http_localhost_8]081 ,界面如下：

![70][]

No application available 没有服务被发现 ，因为没有注册服务。

### 三、创建一个服务提供者 (eureka-client) ###

创建过程同server类似,创建完pom.xml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.demo.erueka</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>com.example.demo</groupId>
    		<artifactId>springcloud-eureka</artifactId>
    		<version>0.0.1-SNAPSHOT</version>
    	</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.boot</groupId>
    			<artifactId>spring-boot-starter</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-web</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>

启动类添加注解@EnableEurekaClient 表明自己是一个eurekaclient.

package com.example.demo.erueka;
    
    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.GetMapping;
    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}")
    	private String port;
    
    	@GetMapping("/test")
    	public String test(String name){
    		return name + "============="+port;
    	}
    }

还需要在配置文件中注明自己的服务注册中心的地址，application.yml配置文件如下：

server:
      port: 8082
    
    spring:
      application:
        name: eureka-client
    
    eureka:
      client:
        serviceUrl:
          defaultZone: http://localhost:8081/eureka/
    #    fetch-registry: false
    #    register-with-eureka: false

注意：需要指明spring.application.name,因为在以后的服务与服务之间相互调用一般都是根据这个name 。

启动工程，打开[http://localhost:80][http_localhost_8]82

![70 1][]

这会你发现一个服务已经注册在服务中了，服务名为SERVICE-CLIENT ,端口为8082

打开 [http://localhost:8082/test?name=][http_localhost_8082_test_name]张三，浏览器上看到 :

张三=============8082

源码下载：[https://download.csdn.net/download/typ1805/10658947][https_download.csdn.net_download_typ1805_10658947]

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![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3R5cDE4MDU_size_16_color_FFFFFF_t_70][]

[http_localhost_8]: http://localhost:8761/
[70]: /images/20210511/cb17043b21ff43568ed95aaf56f430b2.png
[70 1]: /images/20210511/8e656f22118848ad87a63dfcfaaa552a.png
[http_localhost_8082_test_name]: http://localhost:8762/hi?name=forezp
[https_download.csdn.net_download_typ1805_10658947]: https://download.csdn.net/download/typ1805/10658947
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3R5cDE4MDU_size_16_color_FFFFFF_t_70]: /images/20210511/fdce083c65ad48fb8b5806260a28419f.png