pom.xml详解

Posted 2020-10-01

一、什么是POM

Project Object Model，项目对象模型。通过xml格式保存的pom.xml文件。作用类似ant的build.xml文件，功能更强大。该文件用于管理：源代码、配置文件、开发者的信息和角色、问题追踪系统、组织信息、项目授权、项目的url、项目的依赖关系等等。

 

一个完整的pom.xml文件，放置在项目的根目录下。

 

1. <project xmlns="http://maven.apache.org/POM/4.0.0"  
2.   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
3.   xsi:schemaLocation="http://maven.apache.org/POM/4.0.0  
4.                       http://maven.apache.org/maven-v4_0_0.xsd">  
5.   <modelVersion>4.0.0</modelVersion>  
6.   <!– The Basics –>  
7.   <groupId>…</groupId>  
8.   <artifactId>…</artifactId>  
9.   <version>…</version>  
10.   <packaging>…</packaging>  
11.   <dependencies>…</dependencies>  
12.   <parent>…</parent>  
13.   <dependencyManagement>…</dependencyManagement>  
14.   <modules>…</modules>  
15.   <properties>…</properties>  
16.   <!– Build Settings –>  
17.   <build>…</build>  
18.   <reporting>…</reporting>  
19.   <!– More Project Information –>  
20.   <name>…</name>  
21.   <description>…</description>  
22.   <url>…</url>  
23.   <inceptionYear>…</inceptionYear>  
24.   <licenses>…</licenses>  
25.   <organization>…</organization>  
26.   <developers>…</developers>  
27.   <contributors>…</contributors>  
28.   <!– Environment Settings –>  
29.   <issueManagement>…</issueManagement>  
30.   <ciManagement>…</ciManagement>  
31.   <mailingLists>…</mailingLists>  
32.   <scm>…</scm>  
33.   <prerequisites>…</prerequisites>  
34.   <repositories>…</repositories>  
35.   <pluginRepositories>…</pluginRepositories>  
36.   <distributionManagement>…</distributionManagement>  
37.   <profiles>…</profiles>  
38. </project>  

二、基本设置

 

 

1、maven的协作相关属性

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1. <project xmlns="http://maven.apache.org/POM/4.0.0"  
2.   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
3.   xsi:schemaLocation="http://maven.apache.org/POM/4.0.0  
4.                       http://maven.apache.org/maven-v4_0_0.xsd">  
5.   <modelVersion>4.0.0</modelVersion>  
6.   <groupId>org.codehaus.mojo</groupId>  
7.   <artifactId>my-project</artifactId>  
8.   <version>1.0</version>  
9.   <packaging>war</packaging>  
10. </project>  

1. groupId : 组织标识，例如：org.codehaus.mojo，在M2_REPO目录下，将是: org/codehaus/mojo目录。
2. artifactId : 项目名称，例如：my-project，在M2_REPO目录下，将是：org/codehaus/mojo/my-project目录。
3. version : 版本号，例如：1.0，在M2_REPO目录下，将是：org/codehaus/mojo/my-project/1.0目录。
4. packaging : 打包的格式，可以为：pom , jar , maven-plugin , ejb , war , ear , rar , par

2、POM之间的关系

主要用于POM文件的复用。

a）依赖关系：依赖关系列表（dependency list）是POM的重要部分

 

 

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1. <dependencies>  
2.    <dependency>  
3.      <groupId>junit</groupId>  
4.      <artifactId>junit</artifactId>  
5.      <version>4.0</version>  
6.      <scope>test</scope>  
7.    </dependency>  
8.    …  
9.  </dependencies>  

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

b）继承关系：继承其他pom.xml配置的机制。

比如父pom.xml：

 

 

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1. <project>  
2.   [...]  
3.   <dependencies>  
4.     <dependency>  
5.       <groupId>junit</groupId>  
6.       <artifactId>junit</artifactId>  
7.       <version>4.4</version>  
8.       <scope>test</scope>  
9.     </dependency>  
10.   </dependencies>  
11.   [...]  
12. </project>  

在子pom.xml文件继承它的依赖（还可以继承其他的：developers and contributors、plugin lists、reports lists、plugin executions with matching ids、plugin configuration）：

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1. [...]  
2. <parent>  
3. <groupId>com.devzuz.mvnbook.proficio</groupId>  
4.   <artifactId>proficio</artifactId>  
5.   <version>1.0-SNAPSHOT</version>  
6. </parent>  
7. [...]  

在这种机制下，maven还提供了一个类似java.lang.Object的顶级父pom.xml文件：

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1. <project>  
2.   <modelVersion>4.0.0</modelVersion>  
3.   <name>Maven Default Project</name>  
4.   <repositories>  
5.     <repository>  
6.       <id>central</id>  
7.       <name>Maven Repository Switchboard</name>  
8.       <layout>default</layout>  
9.       <url>http://repo1.maven.org/maven2</url>  
10.       <snapshots>  
11.         <enabled>false</enabled>  
12.       </snapshots>  
13.     </repository>  
14.   </repositories>  
15.   <pluginRepositories>  
16.     <pluginRepository>  
17.       <id>central</id>  
18.       <name>Maven Plugin Repository</name>  
19.       <url>http://repo1.maven.org/maven2</url>  
20.       <layout>default</layout>  
21.       <snapshots>  
22.         <enabled>false</enabled>  
23.       </snapshots>  
24.       <releases>  
25.         <updatePolicy>never</updatePolicy>  
26.       </releases>  
27.     </pluginRepository>  
28.   </pluginRepositories>  
29.   <build>  
30.     <directory>target</directory>  
31.     <outputDirectory>target/classes</outputDirectory>  
32.     <finalName>${project.artifactId}-${project.version}</finalName>  
33.     <testOutputDirectory>target/test-classes</testOutputDirectory>  
34.     <sourceDirectory>src/main/java</sourceDirectory>  
35.     <scriptSourceDirectory>src/main/scripts</scriptSourceDirectory>  
36.     <testSourceDirectory>src/test/java</testSourceDirectory>  
37.     <resources>  
38.       <resource>  
39.         <directory>src/main/resources</directory>  
40.       </resource>  
41.     </resources>  
42.     <testResources>  
43.       <testResource>  
44.         <directory>src/test/resources</directory>  
45.       </testResource>  
46.     </testResources>  
47.     <pluginManagement>  
48.        <plugins>  
49.          <plugin>  
50.            <artifactId>maven-antrun-plugin</artifactId>  
51.            <version>1.1</version>  
52.          </plugin>        
53.          <plugin>  
54.            <artifactId>maven-assembly-plugin</artifactId>  
55.            <version>2.2-beta-2</version>  
56.          </plugin>  
57.          <plugin>  
58.            <artifactId>maven-clean-plugin</artifactId>  
59.            <version>2.2</version>  
60.          </plugin>  
61.          <plugin>  
62.            <artifactId>maven-compiler-plugin</artifactId>  
63.            <version>2.0.2</version>  
64.          </plugin>  
65.          <plugin>  
66.            <artifactId>maven-dependency-plugin</artifactId>  
67.            <version>2.0</version>  
68.          </plugin>  
69.          <plugin>  
70.            <artifactId>maven-deploy-plugin</artifactId>  
71.            <version>2.3</version>  
72.          </plugin>  
73.          <plugin>  
74.            <artifactId>maven-ear-plugin</artifactId>  
75.            <version>2.3.1</version>  
76.          </plugin>  
77.          <plugin>  
78.            <artifactId>maven-ejb-plugin</artifactId>  
79.            <version>2.1</version>  
80.          </plugin>  
81.          <plugin>  
82.            <artifactId>maven-install-plugin</artifactId>  
83.            <version>2.2</version>  
84.          </plugin>  
85.          <plugin>  
86.            <artifactId>maven-jar-plugin</artifactId>  
87.            <version>2.2</version>  
88.          </plugin>  
89.          <plugin>  
90.            <artifactId>maven-javadoc-plugin</artifactId>  
91.            <version>2.4</version>  
92.          </plugin>  
93.          <plugin>  
94.            <artifactId>maven-plugin-plugin</artifactId>  
95.            <version>2.4.1</version>  
96.          </plugin>  
97.          <plugin>  
98.            <artifactId>maven-rar-plugin</artifactId>  
99.            <version>2.2</version>  
100.          </plugin>  
101.          <plugin>                 
102.            <artifactId>maven-release-plugin</artifactId>  
103.            <version>2.0-beta-7</version>  
104.          </plugin>  
105.          <plugin>                 
106.            <artifactId>maven-resources-plugin</artifactId>  
107.            <version>2.2</version>  
108.          </plugin>  
109.          <plugin>  
110.            <artifactId>maven-site-plugin</artifactId>  
111.            <version>2.0-beta-6</version>  
112.          </plugin>  
113.          <plugin>  
114.            <artifactId>maven-source-plugin</artifactId>  
115.            <version>2.0.4</version>  
116.          </plugin>           
117.          <plugin>  
118.             <artifactId>maven-surefire-plugin</artifactId>  
119.             <version>2.4.2</version>  
120.          </plugin>  
121.          <plugin>  
122.            <artifactId>maven-war-plugin</artifactId>  
123.            <version>2.1-alpha-1</version>  
124.          </plugin>  
125.        </plugins>  
126.      </pluginManagement>  
127.   </build>  
128.   <reporting>  
129.     <outputDirectory>target/site</outputDirectory>  
130.   </reporting>  
131.   <profiles>  
132.     <profile>  
133.       <id>release-profile</id>  
134.       <activation>  
135.         <property>  
136.           <name>performRelease</name>  
137.           <value>true</value>  
138.         </property>  
139.       </activation>  
140.       <build>  
141.         <plugins>  
142.           <plugin>  
143.             <inherited>true</inherited>  
144.             <groupId>org.apache.maven.plugins</groupId>  
145.             <artifactId>maven-source-plugin</artifactId>  
146.             <executions>  
147.               <execution>  
148.                 <id>attach-sources</id>  
149.                 <goals>  
150.                   <goal>jar</goal>  
151.                 </goals>  
152.               </execution>  
153.             </executions>  
154.           </plugin>  
155.           <plugin>  
156.             <inherited>true</inherited>  
157.             <groupId>org.apache.maven.plugins</groupId>  
158.             <artifactId>maven-javadoc-plugin</artifactId>  
159.             <executions>  
160.               <execution>  
161.                 <id>attach-javadocs</id>  
162.                 <goals>  
163.                   <goal>jar</goal>  
164.                 </goals>  
165.               </execution>  
166.             </executions>  
167.           </plugin>  
168.           <plugin>  
169.             <inherited>true</inherited>  
170.             <groupId>org.apache.maven.plugins</groupId>  
171.             <artifactId>maven-deploy-plugin</artifactId>  
172.             <configuration>  
173.               <updateReleaseInfo>true</updateReleaseInfo>  
174.             </configuration>  
175.           </plugin>  
176.         </plugins>  
177.       </build>  
178.     </profile>  
179.   </profiles>  
180. </project>  

可以通过下面命令查看当前pom.xml受到超pom.xml文件的影响：
mvn help:effective-pom

 

c）聚合关系：用于将多个maven项目聚合为一个大的项目。

 

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1. <project xmlns="http://maven.apache.org/POM/4.0.0"  
2.   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
3.   xsi:schemaLocation="http://maven.apache.org/POM/4.0.0  
4.                       http://maven.apache.org/maven-v4_0_0.xsd">  
5.   <modelVersion>4.0.0</modelVersion>  
6.   <groupId>org.codehaus.mojo</groupId>  
7.   <artifactId>my-parent</artifactId>  
8.   <version>2.0</version>  
9.   <modules>  
10.     <module>my-project<module>  
11.   </modules>  
12. </project>  

 

 

3、属性

 

maven的属性，是值的占位符，类似EL，类似ant的属性，比如${X}，可用于pom文件任何赋值的位置。有以下分类：

 

1. env.X：操作系统环境变量，比如${env.PATH}
2. project.x：pom文件中的属性，比如：<project><version>1.0</version></project>，引用方式：${project.version}
3. settings.x：settings.xml文件中的属性，比如：<settings><offline>false</offline></settings>，引用方式：${settings.offline}
4. Java System Properties：java.lang.System.getProperties()中的属性，比如java.home，引用方式：${java.home}
5. 自定义：在pom文件中可以：<properties><installDir>c:/apps/cargo-installs</installDir></properties>，引用方式：${installDir}

4、构建设置

构建有两种build标签：

 

 

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1. <project xmlns="http://maven.apache.org/POM/4.0.0"  
2.   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
3.   xsi:schemaLocation="http://maven.apache.org/POM/4.0.0  
4.                       http://maven.apache.org/maven-v4_0_0.xsd">  
5.   …  
6.   <!– "Project Build" contains more elements than just the BaseBuild set –>  
7.   <build>…</build>  
8.   <profiles>  
9.     <profile>  
10.       <!– "Profile Build" contains a subset of "Project Build"s elements –>  
11.       <build>…</build>  
12.     </profile>  
13.   </profiles>  
14. </project>  

 

build中的主要标签：Resources和Plugins。

Resources：用于排除或包含某些资源文件

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1. <resources>  
2.   <resource>  
3.     <targetPath>META-INF/plexus</targetPath>  
4.     <filtering>false</filtering>  
5.     <directory>${basedir}/src/main/plexus</directory>  
6.     <includes>  
7.       <include>configuration.xml</include>  
8.     </includes>  
9.     <excludes>  
10.       <exclude>**/*.properties</exclude>  
11.     </excludes>  
12.   </resource>  
13. </resources>  

Plugins：设置构建的插件

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1. <build>  
2.    …  
3.    <plugins>  
4.      <plugin>  
5.        <groupId>org.apache.maven.plugins</groupId>  
6.        <artifactId>maven-jar-plugin</artifactId>  
7.        <version>2.0</version>  
8.        <extensions>false</extensions>  
9.        <inherited>true</inherited>  
10.        <configuration>  
11.          <classifier>test</classifier>  
12.        </configuration>  
13.        <dependencies>…</dependencies>  
14.        <executions>…</executions>  
15.      </plugin>