复杂的maven版本依赖优先级

查看依赖

  • install IDE plugin —— Maven Helper
  • execute goal —— mvn dependency:tree

版本号来源

直接依赖

元素 groupId，artifactId，version，scope，optional，type，classifier，exclusions

唯一标识id：groupId，artifactId，classifier（附属构件）

范围：scope

阻断传播：optional，exclusions

  • 排除依赖是控制当前项目是否使用其直接依赖传递下来的接间依赖；
  • 可选依赖是控制当前项目的依赖是否向下传递；
  • 可选依赖的优先级高于排除依赖；

示例

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<dependency>
    <groupId>com.querydsl</groupId>
    <artifactId>querydsl-apt</artifactId>
    <version>${querydsl.version}</version>
    <scope>provide</scope>
    <optional>false</optional>
    <classifier>jakarta</classifier>
    <type>jar</type>
</dependency>

依赖传递

可以传递的依赖

依赖范围（compile，test，provided，runtime，import，system）

用于控制三种classpath 运行/编译/测试

provided仅在测试和编译时生效，不会打入包中，比如说lombok

runtime仅在测试和运行时生效，打入包中，比如说用法Class.forName(“com.mysql.jdbc.Driver”)

test仅在测试时生效，不会打入包中

当前pom\上层pom provided test runtime compile
provided provided - provided provided
test - - test test
runtime - - runtime runtime
compile - - runtime compile
传递依赖的优先级
路径最近者优先

cache-starter ——> redis-cache ——> cache-base

kafka-mq ——> cache-base

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<dependencies>
     <dependency>
         <groupId>com.jpan</groupId>
         <artifactId>cache-starter</artifactId>
         <version>2.0.0</version>
     </dependency>
     <dependency>
         <groupId>com.jpan</groupId>
         <artifactId>kafka-mq</artifactId>
         <version>1.0.0</version>
     </dependency>
 </dependencies>

example 2

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<dependencyManagement>
       <dependencies>
	<dependency>
              <groupId>com.jpan</groupId>
              <artifactId>cache-base</artifactId>
              <version>2.0.0</version>
          </dependency>
      </dependencies>
  </dependencyManagement>

  <dependencies>
      <dependency>
          <groupId>com.jpan</groupId>
          <artifactId>cache-base</artifactId>
          <version>1.0.0</version>
      </dependency>
  </dependencies>
第一声明者其次

redis-cache ——> cache-base

kafka-mq ——> cache-base

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<dependencies>
       <dependency>
           <groupId>com.jpan</groupId>
           <artifactId>redis-cache</artifactId>
           <version>2.0.0</version>
       </dependency>
       <dependency>
           <groupId>com.jpan</groupId>
           <artifactId>kafka-mq</artifactId>
           <version>1.0.0</version>
       </dependency>
   </dependencies>
同级依赖后加载覆盖先加载
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<dependencies>
       <dependency>
           <groupId>com.jpan</groupId>
           <artifactId>kafka-mq</artifactId>
           <version>2.0.0</version>
       </dependency>
       <dependency>
           <groupId>com.jpan</groupId>
           <artifactId>kafka-mq</artifactId>
           <version>1.0.0</version>
       </dependency>
   </dependencies>

如果用 dependencyManagement管理版本号，顺序会和当前结果不同吗

依赖管理

dependencyManagement doc

依赖继承

继承的pom方式的版本管理比间接依赖的优先级高

可以继承的pom元素 doc

groupId, version, dependencies, dependencyManagement, properties, repositories, build

description，organization，url 等

复杂场景下版本断定

同一级别下pom方式的版本管理路径比间接依赖近

example 1 

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<dependencyManagement>
       <dependencies>
           <dependency>
               <groupId>com.jpan</groupId>
               <artifactId>redis-cache</artifactId>
               <version>1.0.0</version>
           </dependency>
           <dependency>
               <groupId>com.jpan</groupId>
               <artifactId>cache-dependencies</artifactId>
               <version>2.0.0</version>
               <type>pom</type>
               <scope>import</scope>
           </dependency>
       </dependencies>
   </dependencyManagement>

   <dependencies>
       <dependency>
           <groupId>com.jpan</groupId>
           <artifactId>redis-cache</artifactId>
       </dependency>
   </dependencies>

example 2

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<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>com.jpan</groupId>
            <artifactId>cache-dependencies</artifactId>
            <version>2.0.0</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

<dependencies>
    <dependency>
        <groupId>com.jpan</groupId>
        <artifactId>redis-cache</artifactId>
        <version>1.0.0</version>
    </dependency>
</dependencies>

example 3

parent

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<dependencyManagement>
     <dependencies>
         <dependency>
             <groupId>com.jpan</groupId>
             <artifactId>cache-dependencies</artifactId>
             <version>2.0.0</version>
             <type>pom</type>
             <scope>import</scope>
         </dependency>
     </dependencies>
 </dependencyManagement>

当前目录

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<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>com.jpan</groupId>
            <artifactId>redis-cache</artifactId>
            <version>1.0.0</version>
        </dependency>
    </dependencies>
</dependencyManagement>

<dependencies>
    <dependency>
        <groupId>com.jpan</groupId>
        <artifactId>redis-cache</artifactId>
    </dependency>
</dependencies>
父pom传递依赖的路径比当前目录管理传递依赖的路径远

example 1

parent

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<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>com.jpan</groupId>
            <artifactId>redis-cache</artifactId>
            <version>2.0.0</version>
        </dependency>
    </dependencies>
</dependencyManagement>

当前目录

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<dependencyManagement>
       <dependencies>
           <dependency>
               <groupId>com.jpan</groupId>
               <artifactId>redis-cache</artifactId>
               <version>1.0.0</version>
           </dependency>
       </dependencies>
   </dependencyManagement>

   <dependencies>
       <dependency>
           <groupId>com.jpan</groupId>
           <artifactId>redis-cache</artifactId>
       </dependency>
   </dependencies>
第一声明者优先

example 1

两个dependencies管理层级相同

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<dependencyManagement>
       <dependencies>
           <dependency>
               <groupId>com.jpan</groupId>
               <artifactId>cache-dependencies</artifactId>
               <version>1.0.0</version>
               <type>pom</type>
               <scope>import</scope>
           </dependency>
           <dependency>
               <groupId>com.jpan</groupId>
               <artifactId>mq-dependencies</artifactId>
               <version>2.0.0</version>
               <type>pom</type>
               <scope>import</scope>
           </dependency>
       </dependencies>
   </dependencyManagement>

   <dependencies>
       <dependency>
           <groupId>com.jpan</groupId>
           <artifactId>cache-base</artifactId>
       </dependency>
   </dependencies>

example 2

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<dependencyManagement>
       <dependencies>
		<dependency>
              <groupId>com.jpan</groupId>
              <artifactId>cache-base</artifactId>
              <version>2.0.0</version>
          </dependency>
          <dependency>
              <groupId>com.jpan</groupId>
              <artifactId>cache-base</artifactId>
              <version>1.0.0</version>
          </dependency>
      </dependencies>
  </dependencyManagement>
  <dependencies>
      <dependency>
          <groupId>com.jpan</groupId>
          <artifactId>cache-base</artifactId>
      </dependency>
  </dependencies>