Maven子父工程依赖配置，小白也能看得懂

墨蓝 2022-12-28 12:47 198阅读 0赞

# Maven子父工程依赖配置，小白也能看得懂 #

## 1.Maven子父工程依赖配置 ##

你还在对Maven子父工程依赖配置感到疑惑吗？看了这篇文章你讲对它们有个新的认知，小白也能看得懂

在阅读本文之前你要已经了解并使用过maven来管理项目的jar包

直接开干。（下面说的子模块和子工程是同一个意思）

## 2.环境/版本一览： ##

*  开发工具：Intellij IDEA 2020.2.3
 *  jdk：1.8.0\_211
 *  maven: 3.6.3

## 3.创建父工程 ##

*  新建maven项目 这里不要勾选maven模版

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzg5MzU0_size_16_color_FFFFFF_t_70][]

*  设置项目信息

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzg5MzU0_size_16_color_FFFFFF_t_70 1][]

*  修改父工程pom.xml

<?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>com.abc</groupId>
        <artifactId>project</artifactId>
        <version>1.0-SNAPSHOT</version>
    
        
        <packaging>pom</packaging>
    
        
    
        
        <dependencies>
            <dependency>
                <groupId>com.alibaba</groupId>
                <artifactId>fastjson</artifactId>
                <version>1.2.73</version>
            </dependency>
        </dependencies>
        
        <dependencyManagement>
            <dependencies>
                <dependency>
                    <groupId>mysql</groupId>
                    <artifactId>mysql-connector-java</artifactId>
                    <version>5.1.47</version>
                </dependency>
            </dependencies>
        </dependencyManagement>
    
    </project>

父工程的src不含有任何业务逻辑，我们直接将其删除

父工程建好了 依赖也配置好了，接下来我们创建几个子工程

## 4.创建子工程 ##

*  创建project-common

我们在开发中经常有些公共的工具类，现在可以创建一个子工程叫project-common 把这些类都放进去

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzg5MzU0_size_16_color_FFFFFF_t_70 2][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzg5MzU0_size_16_color_FFFFFF_t_70 3][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzg5MzU0_size_16_color_FFFFFF_t_70 4][]

子工程完毕后我们回到父工程的pom.xml  可以发现idea帮我们加入了如下配置。<modules>标签是配置该工程下的子模块名

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzg5MzU0_size_16_color_FFFFFF_t_70 5][]

检查一下project-common工程的pom.xml有没有如下标签 （因为有的idea不会自动加入这个）

<parent>
        <artifactId>project</artifactId>
        <groupId>com.abc</groupId>
        <version>1.0-SNAPSHOT</version>
      </parent>

在这个位置。这是在子模块中配置父工程的信息

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzg5MzU0_size_16_color_FFFFFF_t_70 6][]

*  查看依赖

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzg5MzU0_size_16_color_FFFFFF_t_70 7][]

可以看到子工程并没有引入 父工程<dependencyManagement>里的依赖，只是引入了父工程<dependencies>的依赖

在子工程试一下看能不能使用fastjson包里的内容

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzg5MzU0_size_16_color_FFFFFF_t_70 8][]

可以正常使用

接下来我们在project-common工程里引入一下父工程<dependencyManagement>里的包

*  引入父工程<dependencyManagement>里的包

在project-common工程的pom.xml中的<dependencies>里加入如下配置

<dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
            </dependency>

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzg5MzU0_size_16_color_FFFFFF_t_70 9][]

如果我子工程不想使用父类设置的版本呢

*  重写父工程依赖的版本

还是按照刚才的方式修改一下版本

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzg5MzU0_size_16_color_FFFFFF_t_70 10][]

可以看到子模块的依赖版本被更改了

到此为止子父工程的依赖基本使用就说完了

在实际开发中都是一个父工程有许多子工程，那么一个子工程该如何使用另一个工程的类呢

## 5.子模块之间引用依赖 ##

*  先在project-common创建一个类 MyStringUtils

package com.abc;
    
    /**
     * @description: s
     * @author: nxq email: niuxiangqian163@163.com
     * @createDate: 2020/12/17 3:15 下午
     * @updateUser: nxq email: niuxiangqian163@163.com
     * @updateDate: 2020/12/17 3:15 下午
     * @updateRemark:
     * @version: 1.0
     **/
    public class MyStringUtils {
        /**
         * 判断字符串是否为空
         * @author nxq
         * @param obj:
         * @return boolean
         */
        public static boolean isEmpty(String obj){
            return null == obj || "".equals(obj);
        }
    }

*  再创建一个子工程叫 project-auth

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzg5MzU0_size_16_color_FFFFFF_t_70 11][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzg5MzU0_size_16_color_FFFFFF_t_70 12][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzg5MzU0_size_16_color_FFFFFF_t_70 13][]

创建成功是这样

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzg5MzU0_size_16_color_FFFFFF_t_70 14][]

可以在 project的pom.xml看到新增了如下配置

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzg5MzU0_size_16_color_FFFFFF_t_70 15][]

接下来在project-auth的pom.xml加入如下配置

<parent>
          <artifactId>project</artifactId>
          <groupId>com.abc</groupId>
          <version>1.0-SNAPSHOT</version>
      </parent>
    
    
     <dependency>
          <groupId>com.abc</groupId>
          <artifactId>project-common</artifactId>
          <version>1.0-SNAPSHOT</version>
     </dependency>

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzg5MzU0_size_16_color_FFFFFF_t_70 16][]

去验证一下看能不能在project-auth里使用刚才在project-common创建的工具类MyStringUtil

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzg5MzU0_size_16_color_FFFFFF_t_70 17][]

一顿操作猛如虎，工资得涨三千五，大功告成

## 6.打包 ##

打包直接在父工程下install就行

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzg5MzU0_size_16_color_FFFFFF_t_70 18][]

## 6.补充 ##

刚才新建子工程的时候都是在父工程上右键新建的，如果在子工程上右键那么新建的工程就是被右键的工程的子工程。它们的子父关系与上面解释的同理，可以一层层创建

代码已经推送至github：[https://github.com/NiuXiangQian/parent-children-project][https_github.com_NiuXiangQian_parent-children-project]

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[https_github.com_NiuXiangQian_parent-children-project]: https://github.com/NiuXiangQian/parent-children-project