目录
一、前言
二、父工程搭建
三、公共API项目搭建
四、Eureka Server端搭建
五、Eureka Client【服务提供者】搭建
六、Eureka Client【服务消费者】搭建
七、扩展
一、前言
由于SpringCloud较老版本已经停止更新，已经迭代好几个版本，加上最近SpringCloud Alibaba挺火的，所以想花一点时间去学习一下并总结一番，本文主要搭建Spring Cloud Eureka服务注册中心(单节点)，在生产环境中，基本上都是多节点负载均衡，形成一个服务注册中心集群，这样一个注册中心崩了不会影响整个系统的运行以及接口的调用。
以前已经对老版本的实现方式做了一些总结，有兴趣的小伙伴可以学习一下：/Weixiaohuai/article/details/82498822
版本说明：
SpringBoot：2.2.2.RELEASE
SpringCloud：Hoxton.SR1
二、父工程搭建
由于后面可能会学习Eureka多节点集群搭建、Ribbon负载均衡和SpringCloud Alibaba相关知识，可能会涉及很多子项目，所以这里我们搭建一个父工程用来统一管理这些子module，下面我们可以通过IDEA工具创建一个maven项目。
然后配置maven，点击下一步即可创建完成。由于需要用此父工程对子module用到的依赖包的版本统一进行控制，所以我们需要调整pom.xml：
<?xml version="1.0" encoding="UTF-8"?><project xmlns="/POM/4.0.0"xmlns:xsi="/2001/XMLSchema-instance"xsi:schemaLocation="/POM/4.0.0 /xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.wsh.springcloud</groupId><artifactId>springcloud</artifactId><version>1.0-SNAPSHOT</version><modules><module>springcloud-provider-payment8001</module><module>springcloud-consumer-order80</module><module>springcloud-api-commons</module><module>springcloud-eureka-server7001</module><module>springcloud-eureka-server7002</module><module>springcloud-provider-payment8002</module></modules><packaging>pom</packaging><!-- 统一管理jar包版本 --><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><piler.source>1.8</piler.source><piler.target>1.8</piler.target><junit.version>4.12</junit.version><log4j.version>1.2.17</log4j.version><lombok.version>1.16.18</lombok.version><mysql.version>5.1.47</mysql.version><druid.version>1.1.16</druid.version><mybatis.spring.boot.version>1.3.0</mybatis.spring.boot.version></properties><!-- 子模块继承之后，提供作用：锁定版本 + 子module (不用写groupId和version) --><dependencyManagement><dependencies><!--spring boot 2.2.2--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-dependencies</artifactId><version>2.2.2.RELEASE</version><type>pom</type><scope>import</scope></dependency><!--spring cloud Hoxton.SR1--><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-dependencies</artifactId><version>Hoxton.SR1</version><type>pom</type><scope>import</scope></dependency><!--spring cloud alibaba 2.1.0.RELEASE--><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-alibaba-dependencies</artifactId><version>2.1.0.RELEASE</version><type>pom</type><scope>import</scope></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>${mysql.version}</version></dependency><dependency><groupId>com.alibaba</groupId><artifactId>druid</artifactId><version>${druid.version}</version></dependency><dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>${mybatis.spring.boot.version}</version></dependency><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>${junit.version}</version></dependency><dependency><groupId>log4j</groupId><artifactId>log4j</artifactId><version>${log4j.version}</version></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>${lombok.version}</version><optional>true</optional></dependency></dependencies></dependencyManagement><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId><configuration><fork>true</fork><addResources>true</addResources></configuration></plugin></plugins></build></project>
至此，父工程项目搭建完成。
三、公共API项目搭建
注意，此module主要包含一些公共的实体类、工具类，然后我们结合mvn clean和mvn install后，可以供其他子模块进行在pom.xml中进行引用，避免重复在每个项目中进行声明。
项目名称：springcloud-api-commons
项目结构：
【a】pom.xml
<?xml version="1.0" encoding="UTF-8"?><project xmlns="/POM/4.0.0"xmlns:xsi="/2001/XMLSchema-instance"xsi:schemaLocation="/POM/4.0.0 /xsd/maven-4.0.0.xsd"><parent><artifactId>springcloud</artifactId><groupId>com.wsh.springcloud</groupId><version>1.0-SNAPSHOT</version></parent><modelVersion>4.0.0</modelVersion><artifactId>springcloud-api-commons</artifactId><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-devtools</artifactId><scope>runtime</scope><optional>true</optional></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></dependency><dependency><groupId>cn.hutool</groupId><artifactId>hutool-all</artifactId><version>5.1.0</version></dependency></dependencies></project>
【b】定义统一结果返回类
package com.mon;import lombok.Data;import lombok.NoArgsConstructor;/*** @Description 统一返回结果包装类* @Date /7/26 9:50* @Author weishihuai* 说明:*/@Data@NoArgsConstructorpublic class JsonResult<T> {/*** 状态码*/private Integer code;/*** 返回信息*/private String msg;/*** 返回数据*/private T data;public JsonResult(Integer code, String msg) {this.code = code;this.msg = msg;this.data = null;}public JsonResult(Integer code, String msg, T data) {this.code = code;this.msg = msg;this.data = data;}}
【c】定义实体类，后面用到
package com.wsh.springcloud.entity;import lombok.AllArgsConstructor;import lombok.Data;import lombok.NoArgsConstructor;/*** @Description 支付实体类* @Date /7/26 9:47* @Author weishihuai* 说明:*/@Data@AllArgsConstructor@NoArgsConstructorpublic class Payment {private Long pkid;private String serial;}
然后我们先执行mvn clean, clean完成后再执行mvn install安装到仓库中，这样别的微服务项目在pom.xml中就可以通过springcloud-api-commons项目的G、A、V坐标引入公共魔块。
在别的微服务中引入的方式如下所示：
<!-- 引入自己定义的api通用包，可以使用Payment支付Entity --><dependency><groupId>com.wsh.springcloud</groupId><artifactId>springcloud-api-commons</artifactId><version>${project.version}</version></dependency>
四、Eureka Server端搭建
在父工程的基础上创建一个子module，加入 Eureka-server的依赖。
【a】pom.xml
<?xml version="1.0" encoding="UTF-8"?><project xmlns="/POM/4.0.0"xmlns:xsi="/2001/XMLSchema-instance"xsi:schemaLocation="/POM/4.0.0 /xsd/maven-4.0.0.xsd"><parent><artifactId>springcloud</artifactId><groupId>com.wsh.springcloud</groupId><version>1.0-SNAPSHOT</version></parent><modelVersion>4.0.0</modelVersion><artifactId>springcloud-eureka-server7001</artifactId><dependencies><!--eureka-server--><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-netflix-eureka-server</artifactId></dependency><!-- 引入自己定义的api通用包，可以使用Payment支付Entity --><dependency><groupId>com.wsh.springcloud</groupId><artifactId>springcloud-api-commons</artifactId><version>${project.version}</version></dependency><!--boot web actuator--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-actuator</artifactId></dependency><!--一般通用配置--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-devtools</artifactId><scope>runtime</scope><optional>true</optional></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>junit</groupId><artifactId>junit</artifactId></dependency></dependencies></project>
此处需要注意的是，新版本Eureka Server引入的依赖包为：
spring-cloud-starter-netflix-eureka-server
【b】application.yml
server:port: 7001spring:application:name: springcloud-eureka-server #应用名称eureka:instance:hostname: localhost #eureka服务端的实例名称client:fetch-registry: false #false表示不需要去检索服务实例register-with-eureka: false #false表示不向注册中心注册自己service-url:defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/
【c】主启动类加上@EnableEurekaServer注解，开启Eureka服务发现的功能。
/*** @Description Eureka服务注册中心* @Date /7/26 8:55* @Author weishihuai* 说明:*/@SpringBootApplication//@EnableEurekaServer: 开启Eureka服务注册和发现功能(服务端)@EnableEurekaServerpublic class SpringCloudEurekaServiceApplication7001 {public static void main(String[] args) {SpringApplication.run(SpringCloudEurekaServiceApplication7001.class, args);}}
【d】启动项目，访问localhost:1111/
可见，此时并没有一个微服务客户端注册上来，显示no instance available暂无可用实例。下面我们搭建一个Eureka客户端注册上来。
五、Eureka Client【服务提供者】搭建
新建子模块【springcloud-provider-payment8001】，项目结构如下图：
【a】pom.xml
<?xml version="1.0" encoding="UTF-8"?><project xmlns="/POM/4.0.0"xmlns:xsi="/2001/XMLSchema-instance"xsi:schemaLocation="/POM/4.0.0 /xsd/maven-4.0.0.xsd"><parent><artifactId>springcloud</artifactId><groupId>com.wsh.springcloud</groupId><version>1.0-SNAPSHOT</version></parent><modelVersion>4.0.0</modelVersion><artifactId>springcloud-provider-payment8001</artifactId><dependencies><!-- 引入自己定义的api通用包，可以使用Payment支付Entity --><dependency><groupId>com.wsh.springcloud</groupId><artifactId>springcloud-api-commons</artifactId><version>${project.version}</version></dependency><!--包含了sleuth+zipkin--><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-zipkin</artifactId></dependency><!--eureka-client--><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-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-actuator</artifactId></dependency><dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId></dependency><dependency><groupId>com.alibaba</groupId><artifactId>druid-spring-boot-starter</artifactId><version>1.1.10</version></dependency><!--mysql-connector-java--><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId></dependency><!--jdbc--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-jdbc</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-devtools</artifactId><scope>runtime</scope><optional>true</optional></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency></dependencies></project>
【b】application.yml
server:port: 8001 #指定服务端口号spring:application:name: springcloud-payment-service #指定服务名称datasource:type: com.alibaba.druid.pool.DruidDataSource# 当前数据源操作类型driver-class-name: com.mysql.jdbc.Driver # mysql驱动包&useSSL=falseurl: jdbc:mysql://localhost:3306/springcloud?useUnicode=true&characterEncoding=utf-8 #数据库地址username: root #数据库用户名password: root #数据库用户密码mybatis:mapperLocations: classpath:mapper/*.xml #mapper.xml文件扫描位置type-aliases-package: com.wsh.springcloud.entity # 所有Entity别名类所在包eureka:client:register-with-eureka: true #注册到Eureka注册中心fetch-registry: true #开启检索服务service-url:defaultZone: http://localhost:7001/eureka/ #单机版Eureka注册中心
【c】启动类加上@EnableEurekaClient注解，表示向Eureka Server注册中心注册自己。
package com.wsh.springcloud;import org.mybatis.spring.annotation.MapperScan;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.flix.eureka.EnableEurekaClient;/*** @Description 主启动类* @Date /7/25 9:39* @Author weishihuai* 说明:*/@SpringBootApplication@EnableEurekaClient//@EnableDiscoveryClient@MapperScan("com.wsh.springcloud.mapper")public class PaymentServiceApplication8001 {public static void main(String[] args) {SpringApplication.run(PaymentServiceApplication8001.class, args);}}
【d】由于需要使用mysql数据库，下面是建表sql：
CREATE TABLE `payment` (`pkid` bigint(20) NOT NULL AUTO_INCREMENT COMMENT '主键ID',`serial_number` varchar(200) DEFAULT NULL COMMENT '流水号',PRIMARY KEY (`pkid`)) ENGINE=InnoDB DEFAULT CHARSET=utf8
【e】以下就是一些Controller、Service、Mapper接口和Mapper.xml定义，比较简单，这里就不过多说明。
(一)、PaymentMapper.xml
<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE mapper PUBLIC "-////DTD Mapper 3.0//EN" "/dtd/mybatis-3-mapper.dtd" ><mapper namespace="com.wsh.springcloud.mapper.PaymentMapper"><insert id="save" useGeneratedKeys="true" keyProperty="pkid">insert into payment(serial) values(#{serial});</insert><resultMap id="BaseResultMap" type="com.wsh.springcloud.entity.Payment"><id column="pkid" property="pkid" jdbcType="BIGINT"/><id column="serial" property="serial" jdbcType="VARCHAR"/></resultMap><select id="getPaymentById" parameterType="Long" resultMap="BaseResultMap">select * from payment where pkid = #{pkid};</select></mapper>
(二)、PaymentMapper
package com.wsh.springcloud.mapper;import com.wsh.springcloud.entity.Payment;import org.apache.ibatis.annotations.Mapper;import org.apache.ibatis.annotations.Param;/*** @Description Mapper持久层接口* @Date /7/25 9:53* @Author weishihuai* 说明:*/@Mapperpublic interface PaymentMapper {int save(Payment payment);Payment getPaymentById(@Param("pkid") Long pkid);}
(三)、PaymentService
package com.wsh.springcloud.service;import com.wsh.springcloud.entity.Payment;public interface PaymentService {int save(Payment payment);Payment getPaymentById(Long id);}
(四)、PaymentServiceImpl
package com.wsh.springcloud.service.impl;import com.wsh.springcloud.entity.Payment;import com.wsh.springcloud.mapper.PaymentMapper;import com.wsh.springcloud.service.PaymentService;import org.springframework.stereotype.Service;import javax.annotation.Resource;@Servicepublic class PaymentServiceImpl implements PaymentService {@Resourceprivate PaymentMapper paymentMapper;public int save(Payment payment) {return paymentMapper.save(payment);}public Payment getPaymentById(Long id) {return paymentMapper.getPaymentById(id);}}
(五)、PaymentController
package com.wsh.springcloud.controller;import com.mon.JsonResult;import com.wsh.springcloud.entity.Payment;import com.wsh.springcloud.service.PaymentService;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.beans.factory.annotation.Value;import org.springframework.web.bind.annotation.*;import java.util.concurrent.TimeUnit;@RestControllerpublic class PaymentController {private static final Logger logger = LoggerFactory.getLogger(PaymentController.class);@Autowiredprivate PaymentService paymentService;@Value("${server.port}")private String serverPort;@PostMapping(value = "/payment/save")public JsonResult save(@RequestBody Payment payment) {int result = paymentService.save(payment);logger.info("*****插入结果：" + result);if (result > 0) {return new JsonResult(200, "插入数据库成功,serverPort: " + serverPort, result);} else {return new JsonResult(444, "插入数据库失败", null);}}@GetMapping(value = "/payment/get/{id}")public JsonResult<Payment> getPaymentById(@PathVariable("id") Long id) {Payment payment = paymentService.getPaymentById(id);if (payment != null) {return new JsonResult(200, "查询成功,serverPort: " + serverPort, payment);} else {return new JsonResult(444, "没有对应记录,查询ID: " + id, null);}}}
下面我们启动此项目，观察http://localhost:7001/：
可以看到eureka-client已经成功注册到Eureka上面。
六、Eureka Client【服务消费者】搭建
新建子模块【springcloud-consumer-order80】，项目结构如下图所示：
【a】pm.xml
<?xml version="1.0" encoding="UTF-8"?><project xmlns="/POM/4.0.0"xmlns:xsi="/2001/XMLSchema-instance"xsi:schemaLocation="/POM/4.0.0 /xsd/maven-4.0.0.xsd"><parent><artifactId>springcloud</artifactId><groupId>com.wsh.springcloud</groupId><version>1.0-SNAPSHOT</version></parent><modelVersion>4.0.0</modelVersion><artifactId>springcloud-consumer-order80</artifactId><dependencies><!-- 引入自己定义的api通用包，可以使用Payment支付Entity --><dependency><groupId>com.wsh.springcloud</groupId><artifactId>springcloud-api-commons</artifactId><version>${project.version}</version></dependency><!--包含了sleuth+zipkin--><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-zipkin</artifactId></dependency><!--eureka客户端--><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-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-actuator</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-devtools</artifactId><scope>runtime</scope><optional>true</optional></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency></dependencies></project>
【b】application.yml
server:port: 80spring:application:name: springcloud-order-serviceeureka:instance:hostname: localhostclient:register-with-eureka: true #注册到Eureka注册中心fetch-registry: true #开启检索服务service-url:defaultZone: http://localhost:7001/eureka/ #单机版Eureka注册中心
【c】主启动类
package com.wsh.springcloud;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.flix.eureka.EnableEurekaClient;@SpringBootApplication@EnableEurekaClientpublic class OrderServiceApplication80 {public static void main(String[] args) {SpringApplication.run(OrderServiceApplication80.class, args);}}
【d】配置类
package com.wsh.springcloud.config;import org.springframework.cloud.client.loadbalancer.LoadBalanced;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.web.client.RestTemplate;/*** @Description 全局配置文件类* @Date /7/25 15:45* @Author weishihuai* 说明: 此处配置也可以放在主启动类中*/@Configurationpublic class CustomConfig {//注册到spring ioc容器中@Bean@LoadBalanced //开启负载均衡功能public RestTemplate restTemplate() {return new RestTemplate();}}
【e】Controller
package com.wsh.springcloud.controller;import com.mon.JsonResult;import com.wsh.springcloud.entity.Payment;import lombok.extern.slf4j.Slf4j;import org.springframework.cloud.client.discovery.DiscoveryClient;import org.springframework.http.ResponseEntity;import org.springframework.web.bind.annotation.*;import org.springframework.web.client.RestTemplate;import javax.annotation.Resource;@RestController@Slf4jpublic class OrderController {//支付服务提供者地址// public static final String PAYMENT_URL = "http://localhost:8001";//支付服务提供者注册到Eureka的application namepublic static final String PAYMENT_URL = "http://SPRINGCLOUD-PAYMENT-SERVICE";@Resourceprivate RestTemplate restTemplate;@Resourceprivate DiscoveryClient discoveryClient;@PostMapping("/consumer/payment/save")public JsonResult<Payment> savePayment(@RequestBody Payment payment) {return restTemplate.postForObject(PAYMENT_URL + "/payment/save", payment, JsonResult.class);}@GetMapping("/consumer/payment/get/{id}")public JsonResult<Payment> getPayment(@PathVariable("id") Long id) {return restTemplate.getForObject(PAYMENT_URL + "/payment/get/" + id, JsonResult.class);}@GetMapping("/consumer/payment/getForEntity/{id}")public JsonResult<Payment> getPayment2(@PathVariable("id") Long id) {ResponseEntity<JsonResult> entity = restTemplate.getForEntity(PAYMENT_URL + "/payment/get/" + id, JsonResult.class);if (entity.getStatusCode().is2xxSuccessful()) {return entity.getBody();} else {return new JsonResult<>(444, "操作失败");}}}
启动项目，观察http://localhost:7001/：
可以看到eureka-client已经成功注册到Eureka上面。
接着我们使用postman测试一下，访问http://localhost:80/consumer/payment/get/3，如下图：
可见，已经实现了成功从服务消费者【order端】调用服务提供者【payment端】的接口，这也说明我们Eureka Server成功搭建完成。
七、扩展
Eureka内部维护服务节点的机制：
【a】服务下线
迭代更新、终止访问某一个或者多个服务节点时，在正常关闭服务节点的情况下，Eureka Client会告诉Eureka Server我要下线了，Eureka Server收到请求后会将该服务实例的运行状态由UP修改为DOWN
【b】失效剔除
Eureka Server在启动完成后会创建一个定时器每隔60秒检查一次服务健康状况，如果其中一个服务节点超过90秒未检查到心跳，那么Eureka Server会自动从服务实例列表内将该服务剔除。(内存溢出、杀死进程、服务器宕机等非正常流程关闭服务节点)
【c】自我保护
Eureka Server的自我保护机制会检查最近15分钟内所有Eureka Client正常心跳的占比，如果低于85%就会被触发保护机制，当触发自我保护机制后Eureka Server就会锁定服务列表，不让服务列表内的服务过期，不过这样我们在访问服务时，得到的服务很有可能是已经失效的实例，如果是这样我们就会无法访问到期望的资源，会导致服务调用失败，所以这时我们就需要有对应的容错机制、熔断机制。
关闭自我保护：在application.properties配置文件中加入代码：
eureka.server.enable-self-preservation=false
相关项目的代码我已经放在Gitee上，有需要的小伙伴可以去拉取进行学习：/weixiaohuai/springcloud_Hoxton
以上就是单节点的Eureka服务注册中心搭建的详细过程，由于笔者水平有限，如有不对之处，还请小伙伴们指正，相互学习，一起进步。
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