Maven POM

灰太狼 2020-05-24 13:59 1872阅读 0赞

# 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。

```xml
<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。

------

## 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：

```shell
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：

```xml
<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：

```shell
C:\MVN\project>mvn help:effective-pom
```

Maven 将会开始处理并显示 effective-pom。

```shell
[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
<?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

```xml
<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>

```