超級POM
所有的Maven項目的POM都擴展自超級POM。你可以在${M2_HOME}/lib中的maven-2.0.9-uber.jar文件中找到pom-4.0.0.xml。
超級pom：
<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>target</directory>
    <outputDirectory>target/classes</outputDirectory>
    <finalName>content-zh-0.5</finalName>
    <testOutputDirectory>target/test-classes</testOutputDirectory>
    <sourceDirectory>src/main/java</sourceDirectory>
    <scriptSourceDirectory>src/main/scripts</scriptSourceDirectory>
    <testSourceDirectory>src/test/java</testSourceDirectory>
    <resources>
      <resource>
        <directory>src/main/resources</directory>
      </resource>
    </resources>
    <testResources>
      <testResource>
        <directory>src/test/resources</directory>
      </testResource>
    </testResources>
  </build>

      <pluginManagement>
       <plugins>
         <plugin>
           <artifactId>maven-antrun-plugin</artifactId>
           <version>1.1</version>
         </plugin>      
         <plugin>
           <artifactId>maven-assembly-plugin</artifactId>
           <version>2.2-beta-1</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>2.3</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-6</version>
         </plugin>
         <plugin>
           <artifactId>maven-source-plugin</artifactId>
           <version>2.0.4</version>
         </plugin>        
         <plugin>
            <artifactId>maven-surefire-plugin</artifactId>
            <version>2.4.2</version>
         </plugin>
         <plugin>
           <artifactId>maven-war-plugin</artifactId>
           <version>2.1-alpha-1</version>
         </plugin>
       </plugins>
     </pluginManagement>
 
  <reporting>
    <outputDirectory>target/site</outputDirectory>
  </reporting>
</project>

1).默認的超級POM定義了一個單獨的遠程Maven倉庫，ID為central,這是所有Maven客戶端默認配置訪問的中央Maven倉庫;該配置可以通過一個自定義的settings.xml文件來覆蓋,注意這個默認的超級POM關閉了從中央Maven倉庫下載snapshot構件的功能。如果你需要使用一個snapshot倉庫，你就要在你的pom.xml或者settings.xml中自定義倉庫設置.
2)build元素設置Maven標準目錄布局中那些目錄的默認值.
3)POM中定義的groupId，artifactId和version：這三項是所有項目都需要的坐標