maven pom.xml 詳細

1、什麼是POM

Project Object Model，項目對象模型。經過xml格式保存的pom.xml文件。做用相似ant的build.xml文件，功能更強大。該文件用於管理：源代碼、配置文件、開發者的信息和角色、問題追蹤系統、組織信息、項目受權、項目的url、項目的依賴關係等等。

 

一個完整的pom.xml文件，放置在項目的根目錄下。

 

<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/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <!– The Basics –>
  <groupId>…</groupId>
  <artifactId>…</artifactId>
  <version>…</version>
  <packaging>…</packaging>
  <dependencies>…</dependencies>
  <parent>…</parent>
  <dependencyManagement>…</dependencyManagement>
  <modules>…</modules>
  <properties>…</properties>
  <!– Build Settings –>
  <build>…</build>
  <reporting>…</reporting>
  <!– More Project Information –>
  <name>…</name>
  <description>…</description>
  <url>…</url>
  <inceptionYear>…</inceptionYear>
  <licenses>…</licenses>
  <organization>…</organization>
  <developers>…</developers>
  <contributors>…</contributors>
  <!– Environment Settings –>
  <issueManagement>…</issueManagement>
  <ciManagement>…</ciManagement>
  <mailingLists>…</mailingLists>
  <scm>…</scm>
  <prerequisites>…</prerequisites>
  <repositories>…</repositories>
  <pluginRepositories>…</pluginRepositories>
  <distributionManagement>…</distributionManagement>
  <profiles>…</profiles>
</project>

2、基本設置

 

 

一、maven的協做相關屬性

<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/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>org.codehaus.mojo</groupId>
  <artifactId>my-project</artifactId>
  <version>1.0</version>
  <packaging>war</packaging>
</project>

1. groupId : 組織標識，例如：org.codehaus.mojo，在M2_REPO目錄下，將是: org/codehaus/mojo目錄。
2. artifactId : 項目名稱，例如：my-project，在M2_REPO目錄下，將是：org/codehaus/mojo/my-project目錄。
3. version : 版本號，例如：1.0，在M2_REPO目錄下，將是：org/codehaus/mojo/my-project/1.0目錄。
4. packaging : 打包的格式，能夠爲：pom , jar , maven-plugin , ejb , war , ear , rar , par

二、POM之間的關係

主要用於POM文件的複用。

a）依賴關係：依賴關係列表（dependency list）是POM的重要部分

 

 

<dependencies>
   <dependency>
     <groupId>junit</groupId>
     <artifactId>junit</artifactId>
     <version>4.0</version>
     <scope>test</scope>
   </dependency>
   …
 </dependencies>

1. groupId , artifactId , version :
2. scope : compile(default),provided,runtime,test,system
3. exclusions

b）繼承關係：繼承其餘pom.xml配置的機制。

好比父pom.xml：

 

 

<project>
  [...]
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.4</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
  [...]
</project>

在子pom.xml文件繼承它的依賴（還能夠繼承其餘的：developers and contributors、plugin lists、reports lists、plugin executions with matching ids、plugin configuration）：

[...]
<parent>
<groupId>com.devzuz.mvnbook.proficio</groupId>
  <artifactId>proficio</artifactId>
  <version>1.0-SNAPSHOT</version>
</parent>
[...]

在這種機制下，maven還提供了一個相似java.lang.Object的頂級父pom.xml文件：

<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>${project.artifactId}-${project.version}</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>
    <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>2.4.1</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>
  </build>
  <reporting>
    <outputDirectory>target/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>

能夠經過下面命令查看當前pom.xml受到超pom.xml文件的影響：
mvn help:effective-pom

 

c）聚合關係：用於將多個maven項目聚合爲一個大的項目。

 

<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/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>org.codehaus.mojo</groupId>
  <artifactId>my-parent</artifactId>
  <version>2.0</version>
  <modules>
    <module>my-project<module>
  </modules>
</project>

 

 

三、屬性

 

maven的屬性，是值的佔位符，相似EL，相似ant的屬性，好比${X}，可用於pom文件任何賦值的位置。有如下分類：

 

1. env.X：操做系統環境變量，好比${env.PATH}
2. project.x：pom文件中的屬性，好比：<project><version>1.0</version></project>，引用方式：${project.version}
3. settings.x：settings.xml文件中的屬性，好比：<settings><offline>false</offline></settings>，引用方式：${settings.offline}
4. Java System Properties：java.lang.System.getProperties()中的屬性，好比java.home，引用方式：${java.home}
5. 自定義：在pom文件中能夠：<properties><installDir>c:/apps/cargo-installs</installDir></properties>，引用方式：${installDir}

四、構建設置

構建有兩種build標籤：

 

 

<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/maven-v4_0_0.xsd">
  …
  <!– "Project Build" contains more elements than just the BaseBuild set –>
  <build>…</build>
  <profiles>
    <profile>
      <!– "Profile Build" contains a subset of "Project Build"s elements –>
      <build>…</build>
    </profile>
  </profiles>
</project>

 

build中的主要標籤：Resources和Plugins。

Resources：用於排除或包含某些資源文件

<resources>
  <resource>
    <targetPath>META-INF/plexus</targetPath>
    <filtering>false</filtering>
    <directory>${basedir}/src/main/plexus</directory>
    <includes>
      <include>configuration.xml</include>
    </includes>
    <excludes>
      <exclude>**/*.properties</exclude>
    </excludes>
  </resource>
</resources>

Plugins：設置構建的插件

<build>
   …
   <plugins>
     <plugin>
       <groupId>org.apache.maven.plugins</groupId>
       <artifactId>maven-jar-plugin</artifactId>
       <version>2.0</version>
       <extensions>false</extensions>
       <inherited>true</inherited>
       <configuration>
         <classifier>test</classifier>
       </configuration>
       <dependencies>…</dependencies>
       <executions>…</executions>
     </plugin>