＜dependencyManagement＞的作用

1.简介

dependencyManagement是一个 Maven 项目中的元素，它的作用是集中管理项目的依赖版本

2.为什么要使用dependencyManagement？

在 Maven 中，项目的依赖管理可以在 `元素中配置，但是这些依赖的版本可能会在多个子模块中重复配置，导致维护困难。dependencyManagement`元素的出现就是为了解决这个问题。

3.使用dependencyManagement的好处

使用 `dependencyManagement` 元素，你可以在 Maven 项目的顶层父模块中声明依赖及其对应的版本号，而这些依赖的具体声明则放在各个子模块中。这样一来，子模块无需指定版本号，而是继承自父模块的依赖管理。

4.dependencyManagement的作用

1. 集中管理依赖版本：通过在父模块中声明依赖及版本，可以避免子模块中重复声明相同的版本，简化了配置和维护过程。

2. 强制统一依赖版本：所有依赖的版本由父模块统一管理，可以确保项目中各个模块使用相同的版本，减少潜在的冲突和兼容性问题。

3. 管理依赖的传递性：`dependencyManagement` 中声明的依赖可以自动传递给子模块，无需在每个子模块中显式声明。

5.示例

下面是一个父项目的pom文件，这里拿出来给大家做个示例

依赖部分内容

<dependencyManagement>
        <dependencies>
            
            <dependency>
                <groupId>com.alibabagroupId>
                <artifactId>fastjsonartifactId>
                <version>${fastjson.version}version>
            dependency>
            
            <dependency>
                <groupId>cn.hutoolgroupId>
                <artifactId>hutool-allartifactId>
                <version>${hutool.version}version>
            dependency>
            
            <dependency>
                <groupId>eu.bitwalkergroupId>
                <artifactId>UserAgentUtilsartifactId>
                <version>${bitwalker.version}version>
            dependency>
 
            
            <dependency>
                <groupId>com.github.tobatogroupId>
                <artifactId>fastdfs-clientartifactId>
                <version>${fastdfs.version}version>
            dependency>
 
            
            <dependency>
                <groupId>org.apache.dubbogroupId>
                <artifactId>dubbo-spring-boot-starterartifactId>
                <version>${dubbo.version}version>
            dependency>
            
            <dependency>
                <groupId>org.apache.dubbogroupId>
                <artifactId>dubbo-dependencies-zookeeperartifactId>
                <version>${dubbo.version}version>
                <type>pomtype>
                <exclusions>
                    <exclusion>
                        <groupId>org.slf4jgroupId>
                        <artifactId>slf4j-log4j12artifactId>
                    exclusion>
                exclusions>
            dependency>
 
            
            <dependency>
                <groupId>org.apache.shirogroupId>
                <artifactId>shiro-spring-boot-starterartifactId>
                <version>${shiro-boot.version}version>
            dependency>
            
            <dependency>
                <groupId>org.crazycakegroupId>
                <artifactId>shiro-redisartifactId>
                <version>${shiro-redis.version}version>
            dependency>
 
            
            <dependency>
                <groupId>com.baomidougroupId>
                <artifactId>mybatis-plus-boot-starterartifactId>
                <version>${mybatis-plus.version}version>
            dependency>
        dependencies>
    dependencyManagement>

所有内容

"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">
    <parent>
        <groupId>org.springframework.bootgroupId>
        <artifactId>spring-boot-starter-parentartifactId>
        <version>2.2.6.RELEASEversion>
        <relativePath/>
    parent>
 
    <modelVersion>4.0.0modelVersion>
 
    <groupId>jkw.lifegroupId>
    <artifactId>java-medicalartifactId>
    <version>1.0-SNAPSHOTversion>
    <packaging>pompackaging>
    <description>分布式医疗管理系统description>
 
    <modules>
        <module>medical-configmodule>
        <module>medical-commonsmodule>
        <module>medical-doctormodule>
        <module>medical-erpmodule>
        <module>medical-smsmodule>
        <module>medical-statisticsmodule>
        <module>medical-systemmodule>
    modules>
 
    
    <properties>
        <java.version>1.8java.version>
 
        <fastjson.version>1.2.62fastjson.version>
        <hutool.version>5.1.1hutool.version>
        <bitwalker.version>1.19bitwalker.version>
 
        <mybatis-plus.version>3.3.1.tmpmybatis-plus.version>
        <shiro-boot.version>1.5.3shiro-boot.version>
        <shiro-redis.version>3.2.3shiro-redis.version>
 
        <fastdfs.version>1.26.7fastdfs.version>
        <dubbo.version>2.7.5dubbo.version>
    properties>
 
 
    <dependencyManagement>
        <dependencies>
            
            <dependency>
                <groupId>com.alibabagroupId>
                <artifactId>fastjsonartifactId>
                <version>${fastjson.version}version>
            dependency>
            
            <dependency>
                <groupId>cn.hutoolgroupId>
                <artifactId>hutool-allartifactId>
                <version>${hutool.version}version>
            dependency>
            
            <dependency>
                <groupId>eu.bitwalkergroupId>
                <artifactId>UserAgentUtilsartifactId>
                <version>${bitwalker.version}version>
            dependency>
 
            
            <dependency>
                <groupId>com.github.tobatogroupId>
                <artifactId>fastdfs-clientartifactId>
                <version>${fastdfs.version}version>
            dependency>
 
            
            <dependency>
                <groupId>org.apache.dubbogroupId>
                <artifactId>dubbo-spring-boot-starterartifactId>
                <version>${dubbo.version}version>
            dependency>
            
            <dependency>
                <groupId>org.apache.dubbogroupId>
                <artifactId>dubbo-dependencies-zookeeperartifactId>
                <version>${dubbo.version}version>
                <type>pomtype>
                <exclusions>
                    <exclusion>
                        <groupId>org.slf4jgroupId>
                        <artifactId>slf4j-log4j12artifactId>
                    exclusion>
                exclusions>
            dependency>
 
            
            <dependency>
                <groupId>org.apache.shirogroupId>
                <artifactId>shiro-spring-boot-starterartifactId>
                <version>${shiro-boot.version}version>
            dependency>
            
            <dependency>
                <groupId>org.crazycakegroupId>
                <artifactId>shiro-redisartifactId>
                <version>${shiro-redis.version}version>
            dependency>
 
            
            <dependency>
                <groupId>com.baomidougroupId>
                <artifactId>mybatis-plus-boot-starterartifactId>
                <version>${mybatis-plus.version}version>
            dependency>
        dependencies>
    dependencyManagement>
 
 
project>