maven 继承关系和聚合

maven继承管理 让版本的管理只在一个地方改变

modules用于聚合，把执行的项目都放到同一的地方用module包括，可以省去一个个项目去mvn install,这样可以所有项目一次聚合 mvn install

传递性依赖原则：

A-->B
A-->C

1.路径最近者优先
2.路径相同，第一声明者优先

注意：
1.dependencyManagement中定义的依赖子module不会共享
2.dependencies中定义的依赖子module可以共享

dependencyManagement的使用 就是方便管理版本,子项目中要引入group id和atifact id

在parent项目的pom.xml配置

<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>cn.itcast.maven</groupId>
<artifactId>Parent</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>pom</packaging>

<name>Parent</name>
<url>http://maven.apache.org</url>
<!--聚合-->
<modules>
<module>../Hello</module>
<module>../HelloFriend</module>
<module>../MakeFriends</module>
<module>../Web</module>
</modules>

<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>

<!--定义了依赖的关系，让其他项目继承这些包，不用写版本，同一控制了-->
<dependencyManagement>

<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.9</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>cn.itcast.maven</groupId>
<artifactId>Hello</artifactId>
<version>0.0.1-SNAPSHOT</version>
<scope>compile</scope>
</dependency>
<dependency>
<groupId>cn.itcast.maven</groupId>
<artifactId>HelloFriend</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>cn.itcast.maven</groupId>
<artifactId>MakeFriends</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
</dependencies>
</dependencyManagement>

<distributionManagement>
<repository>
<id>releases</id>
<name>Internal Releases</name>
<url>http://localhost:8080/nexus-2.1.2/content/repositories/releases/</url>
</repository>
<snapshotRepository>
<id>snapshots</id>
<name>Internal Snapshots</name>
<url>http://localhost:8080/nexus-2.1.2/content/repositories/snapshots/</url>
</snapshotRepository>
</distributionManagement>

</project>

Hello.pom

<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>

<artifactId>Hello</artifactId>

<parent>
<groupId>cn.itcast.maven</groupId>
<artifactId>Parent</artifactId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>../Parent/pom.xml</relativePath>
</parent>
<dependencies>
<!--不用写版本了  parent那里同一控制了-->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
</dependency>
</dependencies>

</project>

HelloFriend pom.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>

<artifactId>HelloFriend</artifactId>

<name>HelloFriend</name>

<parent>
<groupId>cn.itcast.maven</groupId>
<artifactId>Parent</artifactId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>../Parent/pom.xml</relativePath>
</parent>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
</dependency>
<dependency>
<groupId>cn.itcast.maven</groupId>
<artifactId>Hello</artifactId>
</dependency>
</dependencies>
</project>