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
1 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 2 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> 3 <modelVersion>4.0.0</modelVersion> 4 5 <groupId>cn.itcast.maven</groupId> 6 <artifactId>Parent</artifactId> 7 <version>0.0.1-SNAPSHOT</version> 8 <packaging>pom</packaging> 9 10 <name>Parent</name> 11 <url>http://maven.apache.org</url> 12 <!--聚合--> 13 <modules> 14 <module>../Hello</module> 15 <module>../HelloFriend</module> 16 <module>../MakeFriends</module> 17 <module>../Web</module> 18 </modules> 19 20 <properties> 21 <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> 22 </properties> 23 24 <!--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--> 25 <dependencyManagement> 26 27 28 <dependencies> 29 <dependency> 30 <groupId>junit</groupId> 31 <artifactId>junit</artifactId> 32 <version>4.9</version> 33 <scope>test</scope> 34 </dependency> 35 <dependency> 36 <groupId>cn.itcast.maven</groupId> 37 <artifactId>Hello</artifactId> 38 <version>0.0.1-SNAPSHOT</version> 39 <scope>compile</scope> 40 </dependency> 41 <dependency> 42 <groupId>cn.itcast.maven</groupId> 43 <artifactId>HelloFriend</artifactId> 44 <version>0.0.1-SNAPSHOT</version> 45 </dependency> 46 <dependency> 47 <groupId>cn.itcast.maven</groupId> 48 <artifactId>MakeFriends</artifactId> 49 <version>0.0.1-SNAPSHOT</version> 50 </dependency> 51 </dependencies> 52 </dependencyManagement> 53 54 <distributionManagement> 55 <repository> 56 <id>releases</id> 57 <name>Internal Releases</name> 58 <url>http://localhost:8080/nexus-2.1.2/content/repositories/releases/</url> 59 </repository> 60 <snapshotRepository> 61 <id>snapshots</id> 62 <name>Internal Snapshots</name> 63 <url>http://localhost:8080/nexus-2.1.2/content/repositories/snapshots/</url> 64 </snapshotRepository> 65 </distributionManagement> 66 67 68 </project>
Hello.pom
1 <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"> 2 <modelVersion>4.0.0</modelVersion> 3 4 <artifactId>Hello</artifactId> 5 6 7 <parent> 8 <groupId>cn.itcast.maven</groupId> 9 <artifactId>Parent</artifactId> 10 <version>0.0.1-SNAPSHOT</version> 11 <relativePath>../Parent/pom.xml</relativePath> 12 </parent> 13 <dependencies> 14 <!--不用写版本了 parent那里同一控制了--> 15 <dependency> 16 <groupId>junit</groupId> 17 <artifactId>junit</artifactId> 18 </dependency> 19 </dependencies> 20 21 </project>
HelloFriend pom.xml
1 <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"> 2 <modelVersion>4.0.0</modelVersion> 3 4 <artifactId>HelloFriend</artifactId> 5 6 <name>HelloFriend</name> 7 8 <parent> 9 <groupId>cn.itcast.maven</groupId> 10 <artifactId>Parent</artifactId> 11 <version>0.0.1-SNAPSHOT</version> 12 <relativePath>../Parent/pom.xml</relativePath> 13 </parent> 14 <dependencies> 15 <dependency> 16 <groupId>junit</groupId> 17 <artifactId>junit</artifactId> 18 </dependency> 19 <dependency> 20 <groupId>cn.itcast.maven</groupId> 21 <artifactId>Hello</artifactId> 22 </dependency> 23 </dependencies> 24 </project>