抽象的阶梯

# 第07章 Maven构建多模块工程

基于上边的三个工程分析

继承：创建一个parent工程将所需的依赖都配置在pom中

聚合：聚合多个模块运行。

# 7.1 需求

将SSM工程拆分为多个模块开发：

  • ssm_dao
  • ssm_service
  • ssm_web

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# 理解继承和聚合

通常继承和聚合同时使用。

何为继承？

继承是为了消除重复，如果将dao、service、web分开创建独立的工程则每个工程的pom.xml文件中的内容存在重复，比如：设置编译版本、锁定spring的版本的等，可以将这些重复的配置提取出来在父工程的pom.xml中定义。

何为聚合？

项目开发通常是分组分模块开发，每个模块开发完成要运行整个工程需要将每个模块聚合在一起运行，比如：dao、service、web三个工程最终会打一个独立的war运行。

# 7.2 案例实现

# 7.2.1 maven-parent父模块

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在父工程的pom.xml中抽取一些重复的配置的，比如：锁定jar包的版本、设置编译版本等。

<properties>
    <spring.version>5.0.2.RELEASE</spring.version>
    <springmvc.version>5.0.2.RELEASE</springmvc.version>
    <mybatis.version>3.4.5</mybatis.version>
</properties>


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

        <!-- springMVC -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${springmvc.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <!-- spring -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aop</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-expression</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-aspects</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-tx</artifactId>
            <version>${spring.version}</version>
        </dependency>

    </dependencies>

</dependencyManagement>

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.1</version>
            <configuration>
                <target>1.8</target>
                <source>1.8</source>
            </configuration>
        </plugin>
    </plugins>
</build>
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父工程创建完成执行install将父工程发布到仓库方便子工程继承：

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# 7.2.2 ssm_dao子模块

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只添加到层的pom，mybatis和spring的整合相关依赖

<dependencies>
    <!-- Mybatis和mybatis与spring的整合 -->
    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis</artifactId>
    </dependency>
    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis-spring</artifactId>
        <version>1.3.1</version>
    </dependency>

    <!-- MySql驱动 -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.32</version>
    </dependency>

    <!-- druid数据库连接池 -->
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>druid</artifactId>
        <version>1.0.9</version>
    </dependency>

    <!-- spring相关 -->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-core</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-aop</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-web</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-expression</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-beans</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-aspects</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context-support</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-test</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-jdbc</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-tx</artifactId>
    </dependency>
</dependencies>
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把文件夹转成sources root

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将ssm_maven工程中的dao接口、映射文件及pojo类拷贝到src/main/java中：

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将applicationContext.xml拆分出一个applicationContext-dao.xml，此文件中只配置dao相关

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:context="http://www.springframework.org/schema/context" xmlns:p="http://www.springframework.org/schema/p"
       xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
   http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd
   http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
   http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.0.xsd">

    <!-- 数据库连接池 -->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <!-- 驱动 -->
        <property name="driverClassName" value="com.mysql.jdbc.Driver" />
        <!-- url -->
        <property name="url" value="jdbc:mysql://localhost:3306/maven" />
        <!-- 用户名 -->
        <property name="username" value="root" />
        <!-- 密码 -->
        <property name="password" value="root" />
    </bean>
    <!-- mapper配置 -->
    <!-- 让spring管理sqlsessionfactory 使用mybatis和spring整合包中的 -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <!-- 数据库连接池 -->
        <property name="dataSource" ref="dataSource" />
        <property name="typeAliasesPackage" value="cn.itcast.ssm.pojo"></property>
    </bean>

    <!-- mapper扫描器 ：用来产生代理对象-->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="basePackage" value="cn.itcast.ssm.dao"></property>
    </bean>
</beans>
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首先在dao模块的pom.xml添加junit的依赖，添加时Scope选择test

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编写junit测试代码

public class ItemsMapperTest {
   @Test
   public void testFindItemsById() {
      //获取spring容器
      ApplicationContext applicationContext = new ClassPathXmlApplicationContext("classpath:applicationContext-dao.xml");
      //获取Mapper
      ItemsMapper itemsMapper =  applicationContext.getBean(ItemsMapper.class);
      //调用Mapper方法
      Items items = itemsMapper.findById(1);
      System.out.println(items);
   }
}
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把dao模块install到本地仓库

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# 7.2.3 ssm_service子模块

方法同ssm_dao模块创建方法，模块名称为ssm_service。

ssm_service模块的pom.xml文件中需要继承父模块，ssm_service依赖ssm_dao模块，添加spring相关的依赖：

<dependencies>
    <!-- spring相关 -->

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-jdbc</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-tx</artifactId>
    </dependency>
    <!--     dao层的依赖 -->
    <dependency>
        <groupId>cn.itcast.ssm</groupId>
        <artifactId>ssm_dao</artifactId>
        <version>1.0-SNAPSHOT</version>
    </dependency>
</dependencies>
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将ssm_maven工程中的service接口拷贝到src/main/java中：

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创建applicationContext-service.xml，此文件中定义的service。

<context:component-scan base-package="cn.itcast.ssm"/>
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# 7.2.4 依赖范围对传递依赖的影响

# 问题描述

当在写junit测试时发现，代码报出没有找不到类的错误信息：

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是因为没有junit.jar引起的!为什么会这样呢？我们ssm_dao模块中有junit依赖而ssm_service模块依赖了ssm_dao，难道junit不应该传递过来吗？

# 依赖范围对传递依赖的影响

是因为依赖会有依赖范围，依赖范围对传递依赖也有影响，例如有A、B、C，A依赖B、B依赖C，C可能是A的传递依赖，如下图：

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最左边一列为直接依赖，理解为A依赖B的范围，最顶层一行为传递依赖，理解为B依赖C的范围，行与列的交叉即为A传递依赖C的范围。

举例1：

比如 A对 B 有 compile 依赖，B 对C有 runtime 依赖，那么根据表格所示A对C 有 runtime 依赖。

ssm_dao依赖junit，scop为test

ssm_service依赖ssm_dao

查看下图红色框内所示传递依赖范围：

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所以ssm_dao工程所依赖的junit的jar没有加入到ssm_service工程。

举例2：

如果修改ssm_dao工程依赖junit的scop为compile，ssm_dao工程所依赖的junit的jar包会加入到ssm_service工程中，符合上边表格所示，查看下图红色框内所示：

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# 单元测试

遇到依赖没有传递过来的问题我们通常的解决方案是在本工程中直接添加依赖：

把如下依赖添加到ssm_service的工程中：

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再看测试代码也不报错了

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install

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# 7.2.5 ssm_web子模块

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ssm_web模块的pom.xml文件中需要继承父模块，ssm_web依赖ssm_service模块,和springmvc的依赖：

<dependencies>
    <!-- 依赖service -->
    <dependency>
        <groupId>cn.itcast.ssm</groupId>
        <artifactId>ssm_service</artifactId>
        <version>1.0-SNAPSHOT</version>
    </dependency>
    <!-- springMVC -->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>${springmvc.version}</version>
    </dependency>
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>servlet-api</artifactId>
        <version>2.5</version>
        <scope>provided</scope>
    </dependency>

    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>jsp-api</artifactId>
        <version>2.0</version>
        <scope>provided</scope>
    </dependency>

    <!-- jstl -->
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>jstl</artifactId>
        <version>1.2</version>
    </dependency>

</dependencies>
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将ssm_web工程中的controller代码拷贝到src/main/java中：

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配置文件

拷贝ssm_web工程中如下配置文件：

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运行调试

方法1：在ssm_web工程的pom.xml中配置tomcat插件运行

运行ssm_web工程它会从本地仓库下载依赖的jar包，所以当ssm_web依赖的jar包内容修改了必须及时发布到本地仓库，比如：ssm_web依赖的ssm_service修改了，需要及时将ssm_service发布到本地仓库。

方法2：在父工程的pom.xml中配置tomcat插件运行，自动聚合并执行

推荐方法2，如果子工程都在本地，采用方法2则不需要子工程修改就立即发布到本地仓库，父工程会自动聚合并使用最新代码执行。

注意：如果子工程和父工程中都配置了tomcat插件，运行的端口和路径以子工程为准。

# 7.3 分模块构建工程--依赖整合

每个模块都需要spring或者junit的jar，况且最终package打完包最后生成的项目中的jar就是各个模块依赖的整合，所以我们可以把项目中所需的依赖都可以放到父工程中,模块中只留模块和模块之间的依赖，那父工程的pom.xml可以如下配置：

<properties>
  <spring.version>5.0.2.RELEASE</spring.version>
  <springmvc.version>5.0.2.RELEASE</springmvc.version>
  <mybatis.version>3.4.5</mybatis.version>
</properties>


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

    <!-- springMVC -->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>${springmvc.version}</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <!-- spring -->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-core</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-aop</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-web</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-expression</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-aspects</artifactId>
      <version>${spring.version}</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context-support</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-test</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-jdbc</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-tx</artifactId>
      <version>${spring.version}</version>
    </dependency>

  </dependencies>

</dependencyManagement>

<dependencies>
  <!-- Mybatis和mybatis与spring的整合 -->
  <dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
  </dependency>
  <dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis-spring</artifactId>
    <version>1.3.1</version>
  </dependency>

  <!-- MySql驱动 -->
  <dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.32</version>
  </dependency>

  <!-- druid数据库连接池 -->
  <dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.0.9</version>
  </dependency>

  <!-- springMVC -->
  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-webmvc</artifactId>
    <version>${springmvc.version}</version>
  </dependency>



  <!-- spring相关 -->
  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-context</artifactId>
  </dependency>
  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-core</artifactId>
  </dependency>

  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-aop</artifactId>
  </dependency>

  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-web</artifactId>
  </dependency>

  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-expression</artifactId>
  </dependency>

  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-beans</artifactId>
  </dependency>


  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-aspects</artifactId>
  </dependency>

  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-context-support</artifactId>
  </dependency>
  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-test</artifactId>
  </dependency>
  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-jdbc</artifactId>
  </dependency>
  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-tx</artifactId>
  </dependency>

  <!-- spring相关 事务相关 -->

  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-jdbc</artifactId>
  </dependency>
  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-tx</artifactId>
  </dependency>

  <!-- junit测试 -->
  <dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.12</version>
    <scope>test</scope>
  </dependency>


  <dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>servlet-api</artifactId>
    <version>2.5</version>
    <scope>provided</scope>
  </dependency>

  <dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>jsp-api</artifactId>
    <version>2.0</version>
    <scope>provided</scope>
  </dependency>

  <!-- jstl -->
  <dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>jstl</artifactId>
    <version>1.2</version>
  </dependency>

</dependencies>


<build>
  <plugins>
    <plugin>
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-compiler-plugin</artifactId>
      <version>3.1</version>
      <configuration>
        <target>1.8</target>
        <source>1.8</source>
      </configuration>
    </plugin>
    <plugin>
      <groupId>org.apache.tomcat.maven</groupId>
      <artifactId>tomcat7-maven-plugin</artifactId>
      <version>2.2</version>
    </plugin>
  </plugins>
</build>
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Last Updated: 10/20/2019, 11:49:45 PM

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