我们在上一章的基础上进行学习。https://blog.csdn.net/qinxun2008081/article/details/131330451

什么是注册中心?它记录了服务和服务地址的映射关系。在分布式架构中，服务会注册到这里，当服务需要调用其它服务时，就到这里找到服务的地址，进行调用。

注册中心的作用就是服务的注册和服务的发现。

一、引入Nacos作为注册中心

我们查看SpringBoot和SpringCloudAlibab的版本匹配

版本说明 · alibaba/spring-cloud-alibaba Wiki · GitHub

在父项目pom.xml中添加Nacos所需的依赖：

<?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>org.example</groupId>
    <artifactId>myshop</artifactId>
    <version>1.0-SNAPSHOT</version>

    <!--设置为pom,管理依赖-->
    <packaging>pom</packaging>
    <modules>
        <module>myshop-common</module>
        <module>myshop-user</module>
        <module>myshop-stock</module>
        <module>myshop-order</module>
        <module>myshop-goods</module>
        <module>myshop-pay</module>
    </modules>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <!--统一管理项目依赖版本-->
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>2.2.6.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <!--cloud-->
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Hoxton.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <!--alibaba-->
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-alibaba-dependencies</artifactId>
                <version>2.2.0.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

</project>

在user子项目引入Nacos

<?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.example</groupId>
        <artifactId>myshop</artifactId>
        <version>1.0-SNAPSHOT</version>
    </parent>

    <artifactId>myshop-user</artifactId>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!--mysql-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.31</version>
        </dependency>
        <!--JPA-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <!--hibernate-validate-->
        <dependency>
            <groupId>org.hibernate.validator</groupId>
            <artifactId>hibernate-validator</artifactId>
        </dependency>
        <!--cloud相关依赖-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
            <version>0.2.2.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba.nacos</groupId>
            <artifactId>nacos-client</artifactId>
        </dependency>
        <!--添加common模块的依赖-->
        <dependency>
            <groupId>org.example</groupId>
            <artifactId>myshop-common</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
    </dependencies>
</project>

二、服务注册

在user模块启动类中添加注解@EnableDiscoveryClient开启服务注册发现功能

package com.example.myshop;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

/**
 * @author qx
 * @date 2023/06/21
 * @desc 启动类
 */
@SpringBootApplication
// 开启服务注册发现
@EnableDiscoveryClient
public class MyShopUserApplication {
    public static void main(String[] args) {
        SpringApplication.run(MyShopUserApplication.class, args);
    }
}

• 在配置文件application.yml中添加服务名称和Nacos Server地址

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://127.0.0.1:3306/myshop?serverTimezone=GMT%2B8&useUnicode=true&characterEncoding=utf-8&useSSL=false&rewriteBatchedStatements=true
    username: root
    password: 123456

  jpa:
    hibernate:
      ddl-auto: update
    show-sql: true

  application:
    #服务名称
    name: user-service
  cloud:
    nacos:
      discovery:
        # Nacos Server地址
        server-addr: 127.0.0.1:8848

• 启动项目，通过Nacos控制台查看，发现用户服务已经注册到了Nacos Server。

最后我们完善其它几个业务子模块，将其它几个业务模块服务也注册到Nacos注册中心 。