maven的聚合模块和pom继承使用(六)

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转载请注明出处哈:http://yanan0628.iteye.com/blog/2270411

1.什么是maven的聚合模块？

聚合模块为项目目录的最顶层，其他模块作为聚合模块子目录而存在。目的是为一次构建多个项目模块。

1.1 项目结构

我自己化了一个关于项目的关系：

1.2 pom标签配置-module

maven-aggregate作为maven pom项目，需要定义pom.xml的 packaging 为 pom类型

我们还是参照 maven的依赖特性,冲突解决(五) 创建 maven-01 maven-02 maven-03工程，通过maven-aggregate pom工程对这三个maven项目做一个聚合，配置如下：

Xml代码

<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.sohu.train</groupId>
<artifactId>maven-aggregate</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>pom</packaging>
<modules>
<module>../maven-01</module>
<module>../maven-02</module>
<module>..maven-03</module>
</modules>
</project>

对 maven-aggregate执行下mvn clean compile

Xml代码

[INFO] Scanning for projects...
[WARNING]
[WARNING] Some problems were encountered while building the effective model for com.sohu.train:maven-02:jar:1.0-SNAPSHORT
[WARNING] 'dependencies.dependency.exclusions.exclusion.groupId' for junit:junit:jar is missing. @ line 38, column 16
[WARNING] 'dependencies.dependency.exclusions.exclusion.artifactId' for junit:junit:jar is missing. @ line 38, column 16
[WARNING]
[WARNING] It is highly recommended to fix these problems because they threaten the stability of your build.
[WARNING]
[WARNING] For this reason, future Maven versions might no longer support building such malformed projects.
[WARNING]
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Build Order: //构建 maven 的反应堆，执行清理编译的顺序
[INFO]
[INFO] maven-02
[INFO] maven-01
[INFO] maven-03
[INFO] maven-aggregate
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building maven-02 1.0-SNAPSHORT
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ maven-02 ---
[INFO] Deleting E:\train\test\maven-02\target
[INFO]
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ maven-02 ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory E:\train\test\maven-02\src\main\resources
[INFO]
[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ maven-02 ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 1 source file to E:\train\test\maven-02\target\classes
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building maven-01 1.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ maven-01 ---
[INFO] Deleting E:\train\test\maven-01\target
[INFO]
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ maven-01 ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Copying 1 resource
[INFO]
[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ maven-01 ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 1 source file to E:\train\test\maven-01\target\classes
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building maven-03 0.0.1-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ maven-03 ---
[INFO] Deleting E:\train\test\maven-03\target
[INFO]
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ maven-03 ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory E:\train\test\maven-03\src\main\resources
[INFO]
[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ maven-03 ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 1 source file to E:\train\test\maven-03\target\classes
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building maven-aggregate 0.0.1-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ maven-aggregate ---
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary: // 可以看到对3个maven项目一起执行编译
[INFO]
[INFO] maven-02 ........................................... SUCCESS [ 1.874 s]
[INFO] maven-01 ........................................... SUCCESS [ 0.108 s]
[INFO] maven-03 ........................................... SUCCESS [ 0.158 s]
[INFO] maven-aggregate .................................... SUCCESS [ 0.002 s]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 2.263 s
[INFO] Finished at: 2016-01-15T14:35:41+08:00
[INFO] Final Memory: 14M/227M
[INFO] ------------------------------------------------------------------------

这样我们就完成 maven对子模块的聚合，像我们平常用的dubbo jetty tomcat spring hibernate等等都是按模块去开发，一次编译各个模块都能紧密联系在一起了。我们在平常开发项目也需要适当的去分模块开发，这是dubbo的子模块，分了很多子模块：

2.什么是pom继承？

pom继承是为了抽出重复配置，通常配置在父模块中，为子模块提供使用，这样可以做到“一处声明，处处使用”。

2.1 继承结构

2.2 pom标签配置-parent,*Management

1.常用的pom被继承的元素

Xml代码

groupId ：项目组 ID ，项目坐标的核心元素；
version ：项目版本，项目坐标的核心元素；
description ：项目的描述信息；
properties ：自定义的 Maven 属性；
dependencies ：项目的依赖配置；
dependencyManagement ：醒目的依赖管理配置；
repositories ：项目的仓库配置；
build ：包括项目的源码目录配置、输出目录配置、插件配置、插件管理配置等；

1.配置maven-aggregate pom文件：

Xml代码

<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.sohu.train</groupId>
<artifactId>maven-aggregate</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>pom</packaging>
<modules>
<module>../maven-01</module>
<module>../maven-02</module>
<module>../maven-03</module>
</modules>
<properties>
<junit.version>3.8.1</junit.version>
</properties>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>${junit.version}</version>
<scope>test</scope>
</dependency>
</dependencies>
</dependencyManagement>
</project>

maven-01,maven-02,maven-03 需要配置parent ,dependencies，同时对junit做一个依赖,3个工程的pom配置如下：

Xml代码

<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>
<parent>
<groupId>com.sohu.train</groupId>
<artifactId>maven-aggregate</artifactId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>../maven-aggregate/pom.xml</relativePath>
</parent>
<artifactId>maven-03</artifactId>
<packaging>jar</packaging>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
</dependency>
</dependencies>
</project>

这样就完成pom的继承，将公用的jar一次配置，就可以实现多处引用了。

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