Maven POM
POM( Project Object Model,项目对象模型 ) 是 Maven 工程的基本工作单元,是一个XML文件,包含了项目的基本信息,用于描述项目如何构建,声明项目依赖,等等。
执行任务或目标时,Maven 会在当前目录中查找 POM。它读取 POM,获取所需的配置信息,然后执行目标。
POM 中可以指定以下配置:
- 项目依赖
- 插件
- 执行目标
- 项目构建 profile
- 项目版本
- 项目开发者列表
- 相关邮件列表信息
在创建 POM 之前,我们首先需要描述项目组 (groupId), 项目的唯一ID。
<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/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.companyname.project-group</groupId>
<artifactId>project</artifactId>
<version>1.0</version>
</project>
所有 POM 文件都需要 project 元素和三个必需字段:groupId,artifactId,version。
节点 |
描述 |
project |
工程的根标签。 |
modelVersion |
模型版本需要设置为 4.0。 |
groupId |
这是工程组的标识。它在一个组织或者项目中通常是唯一的。例如,一个银行组织 com.companyname.project-group 拥有所有的和银行相关的项目。 |
artifactId |
这是工程的标识。它通常是工程的名称。例如,消费者银行。groupId 和 artifactId 一起定义了 artifact 在仓库中的位置。 |
version |
这是工程的版本号。在 artifact 的仓库中,它用来区分不同的版本。例如:
com.company.bank:consumer-banking:1.0
com.company.bank:consumer-banking:1.1
|
父(Super)POM
父(Super)POM是 Maven 默认的 POM。所有的 POM 都继承自一个父 POM(无论是否显式定义了这个父 POM)。父 POM 包含了一些可以被继承的默认设置。因此,当 Maven 发现需要下载 POM 中的 依赖时,它会到 Super POM 中配置的默认仓库 http://repo1.maven.org/maven2 去下载。
Maven 使用 effective pom(Super pom 加上工程自己的配置)来执行相关的目标,它帮助开发者在 pom.xml 中做尽可能少的配置,当然这些配置可以被重写。
使用以下命令来查看 Super POM 默认配置:
mvn help:effective-pom
接下来我们创建目录 MVN/project,在该目录下创建 pom.xml,内容如下:
<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/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.companyname.project-group</groupId>
<artifactId>project</artifactId>
<version>1.0</version>
</project>
在命令控制台,进入 MVN/project 目录,执行以下命令:
C:\MVN\project>mvn help:effective-pom
Maven 将会开始处理并显示 effective-pom。
[INFO] Scanning for projects...
Downloading: https://repo.maven.apache.org/maven2/org/apache/maven/plugins/maven-clean-plugin/2.5/maven-clean-plugin-2.5.pom
...
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 01:36 min
[INFO] Finished at: 2018-09-05T11:31:28+08:00
[INFO] Final Memory: 15M/149M
[INFO] ------------------------------------------------------------------------
Effective POM 的结果就像在控制台中显示的一样,经过继承、插值之后,使配置生效。
<?xml version="1.0" encoding="UTF-8"?>
<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 h
ttp://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.companyname.project-group</groupId>
<artifactId>project</artifactId>
<version>1.0</version>
<build>
<sourceDirectory>C:\MVN\project\src\main\java</sourceDirectory>
<scriptSourceDirectory>src/main/scripts</scriptSourceDirectory>
<testSourceDirectory>C:\MVN\project\src\test\java</testSourceDirectory>
<outputDirectory>C:\MVN\project\target\classes</outputDirectory>
<testOutputDirectory>C:\MVN\project\target\test-classes</testOutputDirectory>
<resources>
<resource>
<mergeId>resource-0</mergeId>
<directory>C:\MVN\project\src\main\resources</directory>
</resource>
</resources>
<testResources>
<testResource>
<mergeId>resource-1</mergeId>
<directory>C:\MVN\project\src\test\resources</directory>
</testResource>
</testResources>
<directory>C:\MVN\project\target</directory>
<finalName>project-1.0</finalName>
<pluginManagement>
<plugins>
<plugin>
<artifactId>maven-antrun-plugin</artifactId>
<version>1.3</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>2.4</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>2.5</version>
</plugin>
<plugin>
<artifactId>maven-plugin-plugin</artifactId>
<version>2.4.3</version>
</plugin>
<plugin>
<artifactId>maven-rar-plugin</artifactId>
<version>2.2</version>
</plugin>
<plugin>
<artifactId>maven-release-plugin</artifactId>
<version>2.0-beta-8</version>
</plugin>
<plugin>
<artifactId>maven-resources-plugin</artifactId>
<version>2.3</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-2</version>
</plugin>
</plugins>
</pluginManagement>
<plugins>
<plugin>
<artifactId>maven-help-plugin</artifactId>
<version>2.1.1</version>
</plugin>
</plugins>
</build>
<repositories>
<repository>
<snapshots>
<enabled>false</enabled>
</snapshots>
<id>central</id>
<name>Maven Repository Switchboard</name>
<url>http://repo1.maven.org/maven2</url>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<releases>
<updatePolicy>never</updatePolicy>
</releases>
<snapshots>
<enabled>false</enabled>
</snapshots>
<id>central</id>
<name>Maven Plugin Repository</name>
<url>http://repo1.maven.org/maven2</url>
</pluginRepository>
</pluginRepositories>
<reporting>
<outputDirectory>C:\MVN\project\target/site</outputDirectory>
</reporting>
</project>
在上面的 pom.xml 中,你可以看到 Maven 在执行目标时需要用到的默认工程源码目录结构、输出目录、需要的插件、仓库和报表目录。
Maven 的 pom.xml 文件也不需要手工编写。
Maven 提供了大量的原型插件来创建工程,包括工程结构和 pom.xml。
POM 标签大全详解
<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/4.0.0http://maven.apache.org/maven-v4_0_0.xsd">
<parent>
<artifactId />
<groupId />
<version />
<relativePath />
</parent>
<modelVersion>4.0.0</modelVersion>
<groupId>asia.banseon</groupId>
<artifactId>banseon-maven2</artifactId>
<packaging>jar</packaging>
<version>1.0-SNAPSHOT</version>
<name>banseon-maven</name>
<url>http://www.baidu.com/banseon</url>
<description>A maven project to study maven.</description>
<prerequisites>
<maven />
</prerequisites>
<issueManagement>
<system>jira</system>
<url>http://jira.baidu.com/banseon</url>
</issueManagement>
<ciManagement>
<system />
<url />
<notifiers>
<notifier>
<type />
<sendOnError />
<sendOnFailure />
<sendOnSuccess />
<sendOnWarning />
<address />
<configuration />
</notifier>
</notifiers>
</ciManagement>
<inceptionYear />
<mailingLists>
<mailingList>
<name>Demo</name>
<post>banseon@126.com</post>
<subscribe>banseon@126.com</subscribe>
<unsubscribe>banseon@126.com</unsubscribe>
<archive>http:/hi.baidu.com/banseon/demo/dev/</archive>
</mailingList>
</mailingLists>
<developers>
<developer>
<id>HELLO WORLD</id>
<name>banseon</name>
<email>banseon@126.com</email>
<url />
<roles>
<role>Project Manager</role>
<role>Architect</role>
</roles>
<organization>demo</organization>
<organizationUrl>http://hi.baidu.com/banseon</organizationUrl>
<properties>
<dept>No</dept>
</properties>
<timezone>-5</timezone>
</developer>
</developers>
<contributors>
<contributor>
<name />
<email />
<url />
<organization />
<organizationUrl />
<roles />
<timezone />
<properties />
</contributor>
</contributors>
<licenses>
<license>
<name>Apache 2</name>
<url>http://www.baidu.com/banseon/LICENSE-2.0.txt</url>
<distribution>repo</distribution>
<comments>A business-friendly OSS license</comments>
</license>
</licenses>
<scm>
<connection>
scm:svn:http://svn.baidu.com/banseon/maven/banseon/banseon-maven2-trunk(dao-trunk)
</connection>
<developerConnection>
scm:svn:http://svn.baidu.com/banseon/maven/banseon/dao-trunk
</developerConnection>
<tag />
<url>http://svn.baidu.com/banseon</url>
</scm>
<organization>
<name>demo</name>
<url>http://www.baidu.com/banseon</url>
</organization>
<build>
<sourceDirectory />
<scriptSourceDirectory />
<testSourceDirectory />
<outputDirectory />
<testOutputDirectory />
<extensions>
<extension>
<groupId />
<artifactId />
<version />
</extension>
</extensions>
<defaultGoal />
<resources>
<resource>
<targetPath />
<filtering />
<directory />
<includes />
<excludes />
</resource>
</resources>
<testResources>
<testResource>
<targetPath />
<filtering />
<directory />
<includes />
<excludes />
</testResource>
</testResources>
<directory />
<finalName />
<filters />
<pluginManagement>
<plugins>
<plugin>
<groupId />
<artifactId />
<version />
<extensions />
<executions>
<execution>
<id />
<phase />
<goals />
<inherited />
<configuration />
</execution>
</executions>
<dependencies>
<dependency>
......
</dependency>
</dependencies>
<inherited />
<configuration />
</plugin>
</plugins>
</pluginManagement>
<plugins>
<plugin>
<groupId />
<artifactId />
<version />
<extensions />
<executions>
<execution>
<id />
<phase />
<goals />
<inherited />
<configuration />
</execution>
</executions>
<dependencies>
<dependency>
......
</dependency>
</dependencies>
<goals />
<inherited />
<configuration />
</plugin>
</plugins>
</build>
<profiles>
<profile>
<id />
<activation>
<activeByDefault />
<jdk />
<os>
<name>Windows XP</name>
<family>Windows</family>
<arch>x86</arch>
<version>5.1.2600</version>
</os>
<property>
<name>mavenVersion</name>
<value>2.0.3</value>
</property>
<file>
<exists>/usr/local/hudson/hudson-home/jobs/maven-guide-zh-to-production/workspace/
</exists>
<missing>/usr/local/hudson/hudson-home/jobs/maven-guide-zh-to-production/workspace/
</missing>
</file>
</activation>
<build>
<defaultGoal />
<resources>
<resource>
<targetPath />
<filtering />
<directory />
<includes />
<excludes />
</resource>
</resources>
<testResources>
<testResource>
<targetPath />
<filtering />
<directory />
<includes />
<excludes />
</testResource>
</testResources>
<directory />
<finalName />
<filters />
<pluginManagement>
<plugins>
<plugin>
<groupId />
<artifactId />
<version />
<extensions />
<executions>
<execution>
<id />
<phase />
<goals />
<inherited />
<configuration />
</execution>
</executions>
<dependencies>
<dependency>
......
</dependency>
</dependencies>
<goals />
<inherited />
<configuration />
</plugin>
</plugins>
</pluginManagement>
<plugins>
<plugin>
<groupId />
<artifactId />
<version />
<extensions />
<executions>
<execution>
<id />
<phase />
<goals />
<inherited />
<configuration />
</execution>
</executions>
<dependencies>
<dependency>
......
</dependency>
</dependencies>
<goals />
<inherited />
<configuration />
</plugin>
</plugins>
</build>
<modules />
<repositories>
<repository>
<releases>
<enabled />
<updatePolicy />
<checksumPolicy />
</releases>
<snapshots>
<enabled />
<updatePolicy />
<checksumPolicy />
</snapshots>
<id />
<name />
<url />
<layout />
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<releases>
<enabled />
<updatePolicy />
<checksumPolicy />
</releases>
<snapshots>
<enabled />
<updatePolicy />
<checksumPolicy />
</snapshots>
<id />
<name />
<url />
<layout />
</pluginRepository>
</pluginRepositories>
<dependencies>
<dependency>
......
</dependency>
</dependencies>
<reports />
<reporting>
......
</reporting>
<dependencyManagement>
<dependencies>
<dependency>
......
</dependency>
</dependencies>
</dependencyManagement>
<distributionManagement>
......
</distributionManagement>
<properties />
</profile>
</profiles>
<modules />
<repositories>
<repository>
<releases>
<enabled />
<updatePolicy />
<checksumPolicy />
</releases>
<snapshots>
<enabled />
<updatePolicy />
<checksumPolicy />
</snapshots>
<id>banseon-repository-proxy</id>
<name>banseon-repository-proxy</name>
<url>http://192.168.1.169:9999/repository/</url>
<layout>default</layout>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
......
</pluginRepository>
</pluginRepositories>
<dependencies>
<dependency>
<groupId>org.apache.maven</groupId>
<artifactId>maven-artifact</artifactId>
<version>3.8.1</version>
<type>jar</type>
<classifier></classifier>
<scope>test</scope>
<systemPath></systemPath>
<exclusions>
<exclusion>
<artifactId>spring-core</artifactId>
<groupId>org.springframework</groupId>
</exclusion>
</exclusions>
<optional>true</optional>
</dependency>
</dependencies>
<reports></reports>
<reporting>
<excludeDefaults />
<outputDirectory />
<plugins>
<plugin>
<groupId />
<artifactId />
<version />
<inherited />
<configuration />
<reportSets>
<reportSet>
<id />
<configuration />
<inherited />
<reports />
</reportSet>
</reportSets>
</plugin>
</plugins>
</reporting>
<dependencyManagement>
<dependencies>
<dependency>
......
</dependency>
</dependencies>
</dependencyManagement>
<distributionManagement>
<repository>
<uniqueVersion />
<id>banseon-maven2</id>
<name>banseon maven2</name>
<url>file://${basedir}/target/deploy</url>
<layout />
</repository>
<snapshotRepository>
<uniqueVersion />
<id>banseon-maven2</id>
<name>Banseon-maven2 Snapshot Repository</name>
<url>scp://svn.baidu.com/banseon:/usr/local/maven-snapshot</url>
<layout />
</snapshotRepository>
<site>
<id>banseon-site</id>
<name>business api website</name>
<url>
scp://svn.baidu.com/banseon:/var/www/localhost/banseon-web
</url>
</site>
<downloadUrl />
<relocation>
<groupId />
<artifactId />
<version />
<message />
</relocation>
<status />
</distributionManagement>
<properties />
</project>
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