如何创建maven项目的多模块项目

Maven多模块项目是指一个Maven项目中包含多个子模块，每个子模块又是一个独立的Maven项目，但它们之间可以存在依赖关系。Maven多模块项目可以方便地管理多个子模块的依赖和构建过程，同时也可以提高项目的可维护性和可扩展性。

创建maven项目的父工程

<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/maven-v4_0_0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.app</groupId><artifactId>study-spring-cloud</artifactId><version>1.0.0</version><packaging>pom</packaging><modules><module>user-service</module><module>order-service</module></modules><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.3.12.RELEASE</version><relativePath/></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>Hoxton.SR12</spring.cloud.version><spring.cloud.alibaba.version>2.2.9.RELEASE</spring.cloud.alibaba.version><mysql.version>8.0.23</mysql.version><druid.version>1.1.23</druid.version><mybatis.plus.version>3.4.2</mybatis.plus.version><hutool.all.version>5.8.23</hutool.all.version></properties><!-- 管理依赖--><dependencyManagement><dependencies><!-- springCloud --><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-dependencies</artifactId><version>${spring.cloud.version}</version><type>pom</type><scope>import</scope></dependency><!-- spring-cloud-alibaba的管理依赖 --><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-alibaba-dependencies</artifactId><version>${spring.cloud.alibaba.version}</version><type>pom</type><scope>import</scope></dependency><!-- mysql驱动 --><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><!--mybatis-plus--><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-boot-starter</artifactId><version>${mybatis.plus.version}</version></dependency><dependency><groupId>cn.hutool</groupId><artifactId>hutool-all</artifactId><version>${hutool.all.version}</version></dependency></dependencies></dependencyManagement><dependencies><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId></dependency></dependencies></project>

说明：
1. modules：用于指定子模块的名称，每个子模块都应该在父项目的同级目录下，可以包含多个module
2. dependencyManagement：用来进行依赖管理的，可以统一在父工程进行版本依赖管理的作用

创建子模块工程user-service

<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/maven-v4_0_0.xsd"><modelVersion>4.0.0</modelVersion><parent><groupId>com.app</groupId><artifactId>study-spring-cloud</artifactId><version>1.0.0</version></parent><artifactId>user-service</artifactId><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId></dependency><!--mybatis-plus--><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-boot-starter</artifactId></dependency><dependency><groupId>com.alibaba</groupId><artifactId>druid</artifactId></dependency><dependency><groupId>cn.hutool</groupId><artifactId>hutool-all</artifactId></dependency></dependencies><build><finalName>app</finalName><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build></project>

创建子模块工程order-service

<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/maven-v4_0_0.xsd"><modelVersion>4.0.0</modelVersion><parent><groupId>com.app</groupId><artifactId>study-spring-cloud</artifactId><version>1.0.0</version></parent><artifactId>order-service</artifactId><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId></dependency><!--mybatis-plus--><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-boot-starter</artifactId></dependency><dependency><groupId>com.alibaba</groupId><artifactId>druid</artifactId></dependency></dependencies><build><finalName>app</finalName><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build></project>