maven 学习笔记（3）——聚合(多模块)和继承

WuJunwei

Jun 23, 2020

It takes 31 minutes to read this article.

创建父工程;创建web工程;创建service工程;创建mapper工程;项目结构; 依赖的统一管理

多模块（聚合）：将maven项目分解，为了统一开发和代码复用；

继承：使用pom配置，为了统一管理并消除重复；

聚合主要为了快速构建项目，继承主要为了消除重复

提示：两者虽然概念不同，但在企业中会一起使用。

示例：构建一个父工程，多个子工程，让父工程管理子工程。

创建父工程（usermanage-parent）

跳过骨架创建maven工程：

new maven project
勾选使用简单骨架
打包方式为pom
点击“finish”

创建web工程（usermanage-web）

右键usermanage-parent工程，创建maven module模块
勾选使用简单骨架，填写模块名称
注意打包方式选择war
点击“finish”

不要忘了maven刷新工程，并添加web.xml

把usermanage工程中的controller层的代码放入usermanage-web工程：

创建service工程（usermanage-service）

创建usermanage-service模块
勾选使用简单骨架
打包方式选jar
点击“finish”

把usermanage工程中的service层的代码放入usermanage-web工程：

创建mapper工程（usermanage-mapper）

同service工程

把usermanage工程中的mapper层的代码放入usermanage-web工程：

项目结构

打开usermanage-parent的pom.xml会发现有段儿配置：

打开工作空间,发现只有父工程目录，没有子模块目录

打开工作空间中的usermanage-parent工程，查看目录结构：子模块对应的目录都在父工程中。

依赖的统一管理

在usermanage-parent父工程的pom.xml中配置：

<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.atguigu.usermanage</groupId>
	<artifactId>usermanage-parent</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>pom</packaging>

	<!-- 集中定义依赖版本号 -->
	<properties>
		<junit.version>4.10</junit.version>
		<spring.version>4.3.22.RELEASE</spring.version>
		<mybatis.version>3.4.1</mybatis.version>
		<mybatis.spring.version>1.3.2</mybatis.spring.version>
		<mysql.version>5.1.37</mysql.version>
		<slf4j.version>1.6.4</slf4j.version>
		<jackson.version>2.9.5</jackson.version>
		<c3p0.version>0.9.1.2</c3p0.version>
		<hibernate.version>5.1.3.Final</hibernate.version>
		<jstl.version>1.2</jstl.version>
		<servlet-api.version>2.5</servlet-api.version>
		<jsp-api.version>2.0</jsp-api.version>
	</properties>

	<!--只是起到管理版本号的作用-->
	<dependencyManagement>
		<dependencies>
			<!-- 单元测试 -->
			<dependency>
				<groupId>junit</groupId>
				<artifactId>junit</artifactId>
				<version>${junit.version}</version>
				<scope>test</scope>
			</dependency>

			<!-- Spring -->
			<dependency>
				<groupId>org.springframework</groupId>
				<artifactId>spring-context</artifactId>
				<version>${spring.version}</version>
			</dependency>
			<dependency>
				<groupId>org.springframework</groupId>
				<artifactId>spring-beans</artifactId>
				<version>${spring.version}</version>
			</dependency>
			<dependency>
				<groupId>org.springframework</groupId>
				<artifactId>spring-webmvc</artifactId>
				<version>${spring.version}</version>
			</dependency>
			<dependency>
				<groupId>org.springframework</groupId>
				<artifactId>spring-jdbc</artifactId>
				<version>${spring.version}</version>
			</dependency>
			<dependency>
				<groupId>org.springframework</groupId>
				<artifactId>spring-aspects</artifactId>
				<version>${spring.version}</version>
			</dependency>

			<!-- Mybatis -->
			<dependency>
				<groupId>org.mybatis</groupId>
				<artifactId>mybatis</artifactId>
				<version>${mybatis.version}</version>
			</dependency>
			<dependency>
				<groupId>org.mybatis</groupId>
				<artifactId>mybatis-spring</artifactId>
				<version>${mybatis.spring.version}</version>
			</dependency>

			<!-- MySql -->
			<dependency>
				<groupId>mysql</groupId>
				<artifactId>mysql-connector-java</artifactId>
				<version>${mysql.version}</version>
			</dependency>

			<dependency>
				<groupId>org.hibernate</groupId>
				<artifactId>hibernate-validator</artifactId>
				<version>${hibernate.version}</version>
			</dependency>

			<dependency>
				<groupId>org.slf4j</groupId>
				<artifactId>slf4j-log4j12</artifactId>
				<version>${slf4j.version}</version>
			</dependency>

			<!-- Jackson Json处理工具包 -->
			<dependency>
				<groupId>com.fasterxml.jackson.core</groupId>
				<artifactId>jackson-databind</artifactId>
				<version>${jackson.version}</version>
			</dependency>

			<!-- 连接池 -->
			<dependency>
				<groupId>c3p0</groupId>
				<artifactId>c3p0</artifactId>
				<version>${c3p0.version}</version>
			</dependency>

			<!-- JSP相关 -->
			<dependency>
				<groupId>jstl</groupId>
				<artifactId>jstl</artifactId>
				<version>${jstl.version}</version>
			</dependency>
			<dependency>
				<groupId>javax.servlet</groupId>
				<artifactId>servlet-api</artifactId>
				<version>${servlet-api.version}</version>
				<scope>provided</scope>
			</dependency>
			<dependency>
				<groupId>javax.servlet</groupId>
				<artifactId>jsp-api</artifactId>
				<version>${jsp-api.version}</version>
				<scope>provided</scope>
			</dependency>

		</dependencies>
	</dependencyManagement>
	
	<build>
		<pluginManagement>
			<plugins>
				<!-- 配置Tomcat插件 -->
				<plugin>
					<groupId>org.apache.tomcat.maven</groupId>
					<artifactId>tomcat7-maven-plugin</artifactId>
					<version>2.2</version>
				</plugin>
			</plugins>
		</pluginManagement>
	</build>

	<modules>
		<module>usermanage-web</module>
		<module>usermanage-service</module>
		<module>usermanage-mapper</module>
	</modules>

</project>

引入依赖

子工程之间的依赖关系：

usermanage-web usermanageservice usermanage-mapper

解决代码报错，需要引入相关依赖。引入依赖的原则是：

所有的工程都需要的依赖应该在聚合工程（usermanage-parent）中导入。
在使用依赖的最底层导入。
运行时所需要的依赖在web工程中加入。

usermanage-web工程的pom.xml:

<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>com.atguigu.usermanage</groupId>
		<artifactId>usermanage-parent</artifactId>
		<version>0.0.1-SNAPSHOT</version>
	</parent>
	<artifactId>usermanage-web</artifactId>
	<packaging>war</packaging>
	<dependencies>
		<dependency>
			<groupId>com.atguigu.usermanage</groupId>
			<artifactId>usermanage-service</artifactId>
			<version>0.0.1-SNAPSHOT</version>
		</dependency>
	
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<scope>test</scope>
		</dependency>
		
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-webmvc</artifactId>
		</dependency>

		<!-- 运行时依赖 -->
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-jdbc</artifactId>
		</dependency>

		<!-- 运行时依赖 -->
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-aspects</artifactId>
		</dependency>

		<!-- 运行时依赖 -->
		<dependency>
			<groupId>org.mybatis</groupId>
			<artifactId>mybatis-spring</artifactId>
		</dependency>
		
		<!-- 运行时依赖 -->
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
		</dependency>

		<!-- 运行时依赖 -->
		<dependency>
			<groupId>org.slf4j</groupId>
			<artifactId>slf4j-log4j12</artifactId>
		</dependency>
		
		<!-- 运行时依赖 -->
		<dependency>
			<groupId>c3p0</groupId>
			<artifactId>c3p0</artifactId>
		</dependency>

		<!-- JSP相关 -->
		<dependency>
			<groupId>jstl</groupId>
			<artifactId>jstl</artifactId>
		</dependency>
		<dependency>
			<groupId>javax.servlet</groupId>
			<artifactId>servlet-api</artifactId>
			<scope>provided</scope>
		</dependency>
		<dependency>
			<groupId>javax.servlet</groupId>
			<artifactId>jsp-api</artifactId>
			<scope>provided</scope>
		</dependency>

	</dependencies>
	<build>
		<plugins>
			<!-- 配置Tomcat插件 -->
			<plugin>
				<groupId>org.apache.tomcat.maven</groupId>
				<artifactId>tomcat7-maven-plugin</artifactId>
				<configuration>
					<!-- 配置它之后，不需要项目名就可以访问 -->
					<path>/</path>
					<!-- 配置端口 -->
					<port>8080</port>
				</configuration>
			</plugin>
		</plugins>
	</build>
</project>

Usermanage-service的pom.xml：

<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>com.atguigu.usermanage</groupId>
		<artifactId>usermanage-parent</artifactId>
		<version>0.0.1-SNAPSHOT</version>
	</parent>
	<artifactId>usermanage-service</artifactId>

	<dependencies>

		<dependency>
			<groupId>com.atguigu.usermanage</groupId>
			<artifactId>usermanage-mapper</artifactId>
			<version>0.0.1-SNAPSHOT</version>
		</dependency>

	</dependencies>

</project>

Usermanage-mapper的pom.xml：

<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>com.atguigu.usermanage</groupId>
		<artifactId>usermanage-parent</artifactId>
		<version>0.0.1-SNAPSHOT</version>
	</parent>
	<artifactId>usermanage-mapper</artifactId>
	<dependencies>
		<dependency>
			<groupId>org.mybatis</groupId>
			<artifactId>mybatis</artifactId>
		</dependency>
		<dependency>
			<groupId>org.hibernate</groupId>
			<artifactId>hibernate-validator</artifactId>
		</dependency>
		<dependency>
			<groupId>com.fasterxml.jackson.core</groupId>
			<artifactId>jackson-databind</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-context</artifactId>
		</dependency>
	</dependencies>
</project>

运行测试

右键父工程
tomcat7:run