maven pom.xml 详细

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

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

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：

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）：

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：

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。

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：

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

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

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>