Maven2学习笔记(2)——POM文件_汉学堂的博客_百度空间企业库|免费b2b网站

Maven2学习笔记(2)——POM文件_汉学堂的博客_百度空间

1.什么是POM

POM，即Project Object Model，通过pom.xml文件配置Maven2，然后Maven2根据此配置执行。

2.Super POM

Super POM是Maven2的默认pom.xml文件，无需显示声明，所有的pom.xml文件都默认继承此文件。
2.0.x的默认Super POM文件如下：

<project>
<modelVersion>4.0.0</modelVersion>
<name>Maven Default Project</name>

<repositories>
    <repository>
      <id>central</id>
      <name>Maven Repository Switchboard</name>
      <layout>default</layout>
      <url>http://repo1.maven.org/maven2</url>
      <snapshots>
        <enabled>false</enabled>
      </snapshots>
    </repository>
</repositories>

<pluginRepositories>
    <pluginRepository>
      <id>central</id>
      <name>Maven Plugin Repository</name>
      <url>http://repo1.maven.org/maven2</url>
      <layout>default</layout>
      <snapshots>
        <enabled>false</enabled>
      </snapshots>
      <releases>
        <updatePolicy>never</updatePolicy>
      </releases>
    </pluginRepository>
</pluginRepositories>

<build>
    <directory>${project.basedir}/target</directory>
    <outputDirectory>${project.build.directory}/classes</outputDirectory>
    <finalName>${project.artifactId}-${project.version}</finalName>
    <testOutputDirectory>${project.build.directory}/test-classes</testOutputDirectory>
    <sourceDirectory>${project.basedir}/src/main/java</sourceDirectory>
    <scriptSourceDirectory>${project.basedir}/src/main/scripts</scriptSourceDirectory>
    <testSourceDirectory>${project.basedir}/src/test/java</testSourceDirectory>
    <resources>
      <resource>
        <directory>${project.basedir}/src/main/resources</directory>
      </resource>
    </resources>
    <testResources>
      <testResource>
        <directory>${project.basedir}/src/test/resources</directory>
      </testResource>
    </testResources>
    <pluginManagement>
       <plugins>
         <plugin>
           <artifactId>maven-antrun-plugin</artifactId>
           <version>1.1</version>
         </plugin>
         <plugin>
           <artifactId>maven-assembly-plugin</artifactId>
           <version>2.2-beta-2</version>
         </plugin>
         <plugin>
           <artifactId>maven-clean-plugin</artifactId>
           <version>2.2</version>
         </plugin>
         <plugin>
           <artifactId>maven-compiler-plugin</artifactId>
           <version>2.0.2</version>
         </plugin>
         <plugin>
           <artifactId>maven-dependency-plugin</artifactId>
           <version>2.0</version>
         </plugin>
         <plugin>
           <artifactId>maven-deploy-plugin</artifactId>
           <version>2.3</version>
         </plugin>
         <plugin>
           <artifactId>maven-ear-plugin</artifactId>
           <version>2.3.1</version>
         </plugin>
         <plugin>
           <artifactId>maven-ejb-plugin</artifactId>
           <version>2.1</version>
         </plugin>
         <plugin>
           <artifactId>maven-install-plugin</artifactId>
           <version>2.2</version>
         </plugin>
         <plugin>
           <artifactId>maven-jar-plugin</artifactId>
           <version>2.2</version>
         </plugin>
         <plugin>
           <artifactId>maven-javadoc-plugin</artifactId>
           <version>2.4</version>
         </plugin>
         <plugin>
           <artifactId>maven-plugin-plugin</artifactId>
           <version>2.4.2</version>
         </plugin>
         <plugin>
           <artifactId>maven-rar-plugin</artifactId>
           <version>2.2</version>
         </plugin>
         <plugin>
           <artifactId>maven-release-plugin</artifactId>
           <version>2.0-beta-7</version>
         </plugin>
         <plugin>
           <artifactId>maven-resources-plugin</artifactId>
           <version>2.2</version>
         </plugin>
         <plugin>
           <artifactId>maven-site-plugin</artifactId>
           <version>2.0-beta-7</version>
         </plugin>
         <plugin>
           <artifactId>maven-source-plugin</artifactId>
           <version>2.0.4</version>
         </plugin>
         <plugin>
            <artifactId>maven-surefire-plugin</artifactId>
            <version>2.4.3</version>
         </plugin>
         <plugin>
           <artifactId>maven-war-plugin</artifactId>
           <version>2.1-alpha-1</version>
         </plugin>
       </plugins>
     </pluginManagement>
</build>

<reporting>
    <outputDirectory>${project.build.directory}/site</outputDirectory>
</reporting>
<profiles>
    <profile>
      <id>release-profile</id>

      <activation>
        <property>
          <name>performRelease</name>
          <value>true</value>
        </property>
      </activation>

      <build>
        <plugins>
          <plugin>
            <inherited>true</inherited>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-source-plugin</artifactId>
            <executions>
              <execution>
                <id>attach-sources</id>
                <goals>
                  <goal>jar</goal>
                </goals>
              </execution>
            </executions>
          </plugin>
          <plugin>
            <inherited>true</inherited>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-javadoc-plugin</artifactId>
            <executions>
              <execution>
                <id>attach-javadocs</id>
                <goals>
                  <goal>jar</goal>
                </goals>
              </execution>
            </executions>
          </plugin>
          <plugin>
            <inherited>true</inherited>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-deploy-plugin</artifactId>
            <configuration>
              <updateReleaseInfo>true</updateReleaseInfo>
            </configuration>
          </plugin>
        </plugins>
      </build>
    </profile>
</profiles>

</project>

3.Minimal POM

最小的POM文件应该具有以下几个元素

project root
modelVersion - should be set to 4.0.0
groupId - the id of the project's group.
artifactId - the id of the artifact (project)
version - the version of the artifact under the specified group

4.Project Inheritance(注意，是继承而不是组合)

POM中的以下元素会被合并:

    * dependencies
    * developers and contributors
    * plugin lists (including reports)
    * plugin executions with matching ids
    * plugin configuration
    * resources

示例：

设pom.xml文件为
<project>
<modelVersion>4.0.0</modelVersion>
<groupId>com.mycompany.app</groupId>
<artifactId>my-app</artifactId>
<version>1</version>
</project>

1.标准目录结构下的继承

.
 |-- my-module
 |   `-- pom.xml
 `-- pom.xml

my-module下的pom.xml文件为

<project>
  <parent>
    <groupId>com.mycompany.app</groupId>
    <artifactId>my-app</artifactId>
    <version>1</version>
  </parent>
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.mycompany.app</groupId>  //可以省略，省略则继承parent pom相同的groupId
  <artifactId>my-module</artifactId>
  <version>1</version>
</project>

2.非标准目录结构下的继承
.

 |-- my-module
 |   `-- pom.xml
 `-- parent
     `-- pom.xml

<project>
  <parent>
    <groupId>com.mycompany.app</groupId>
    <artifactId>my-app</artifactId>
    <version>1</version>
    <relativePath>../parent/pom.xml</relativePath>    //注意这里的区别
  </parent>
  <modelVersion>4.0.0</modelVersion>
  <artifactId>my-module</artifactId>
</project>

5. Project Aggresgation

改用组合，需要做以下工作

Change the parent POMs packaging to the value "pom" .
Specify in the parent POM the directories of its modules (children POMs)

即，通过在parent pom文件中添加以下元素，即可
<modules>
  <module>relativePath/To/Module</module>  //如果是标准目录结构，则直接指定子模块文件夹名
  ...
</modules>

6.Aggregation和Inheritance的区别

当构建一个工程时，需要执行几个子工程，那么就可以使用aggregation

当需要抽取多个工程中的相同配置的话，那么可以使用inheritance

实际使用中，往往两者相结合使用，方法如下：

Specify in every child POM who their parent POM is.
Change the parent POMs packaging to the value "pom" .
Specify in the parent POM the directories of its modules (children POMs)

郑重声明：资讯【Maven2学习笔记(2)——POM文件_汉学堂的博客_百度空间】由发布，版权归原作者及其所在单位，其原创性以及文中陈述文字和内容未经(企业库qiyeku.com)证实，请读者仅作参考，并请自行核实相关内容。若本文有侵犯到您的版权，请你提供相关证明及申请并与我们联系（qiyeku # qq.com）或【在线投诉】，我们审核后将会尽快处理。

—— 相关资讯 ——