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23.5. Maven Module
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23.5. Maven Module

对于大型互联网项目，不可能把所有代码都放在一个项目目录下，常常会将一个项目拆分成多个子项目

例如一个电商系统

  1. 网站
  2. 资讯中心
  3. 商品中心
  4. 物流中心
  5. 订单中心
  6. 客服中心
  7. 后台

在开发过程中常常会遇到这种需求，有一个部分代码是共用的，所有项目都会使用到。所以需要将这部分代码独立成一个项目。

测试目录深度

		
Project
    |
    |--- common -> https://example.com/xxxx/common.git
    |     | ---pom.xml
    |--- project1
    |     |--- pom.xml
    |--- project2
    |     |--- pom.xml
    |---pom.xml

common 是公共项目，独立仓库。通过git submodule 技术挂载到项目目录。project1，project2 构建依赖 common 项目产生的 jar 包。

23.5.1. Parent

例 23.4. Maven parent

				
<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>

	<groupId>demo</groupId>
	<artifactId>maven</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>pom</packaging>

	<name>maven</name>
	<url>http://maven.apache.org</url>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<maven.compiler.source>11</maven.compiler.source>
		<maven.compiler.target>${maven.compiler.source}</maven.compiler.target>
		<junit.jupiter.version>5.4.0</junit.jupiter.version>
	</properties>

	<dependencies>


	</dependencies>
	<modules>
		<module>project1</module>
		<module>project2</module>
		<module>common</module>
	</modules>
	<build>

		<plugins>
			<plugin>
				<artifactId>maven-surefire-plugin</artifactId>
				<version>3.0.0-M3</version>
			</plugin>
			<plugin>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>3.8.0</version>
			</plugin>

		</plugins>
	</build>
</project>

注意

			
<packaging>pom</packaging> 必须是 pom

项目下面的子模块

			
    <modules>
		<module>project1</module>
		<module>project2</module>
		<module>common</module>
    </modules>

23.5.2. 公共项目 common

例 23.5. watir-webdriver example

				
<?xml version="1.0"?>
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>demo</groupId>
		<artifactId>maven</artifactId>
		<version>0.0.1-SNAPSHOT</version>
	</parent>
	<groupId>demo</groupId>
	<artifactId>common</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>common</name>
	<url>http://maven.apache.org</url>
	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
	</properties>
	<dependencies>

	</dependencies>
</project>

添加 parent 标签, 声明项目的父子关系

			
    <parent>
		<groupId>demo</groupId>
		<artifactId>maven</artifactId>
		<version>0.0.1-SNAPSHOT</version>
    </parent>

23.5.3. 常规项目

			
<?xml version="1.0"?>
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>demo</groupId>
		<artifactId>maven</artifactId>
		<version>0.0.1-SNAPSHOT</version>
	</parent>
	<groupId>demo</groupId>
	<artifactId>project1</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>project1</name>
	<url>http://maven.apache.org</url>
	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
	</properties>
	<dependencies>
		<dependency>
			<groupId>demo</groupId>
			<artifactId>common</artifactId>
			<version>0.0.1-SNAPSHOT</version>
		</dependency>
	</dependencies>
</project>

声明项目的父子关系

			
    <parent>
		<groupId>demo</groupId>
		<artifactId>maven</artifactId>
		<version>0.0.1-SNAPSHOT</version>
	</parent>

由于 project1 依赖 common 加入下面依赖

			
		<dependency>
			<groupId>demo</groupId>
			<artifactId>common</artifactId>
			<version>0.0.1-SNAPSHOT</version>
		</dependency>

project2 跟 project1 类似

23.5.4. 现在测试效果

在父项目目录运行 mvn package

			
neo@MacBook-Pro ~/workspace/maven % mvn package
[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Build Order:
[INFO] 
[INFO] maven                                                              [pom]
[INFO] common                                                             [jar]
[INFO] project1                                                           [jar]
[INFO] project2                                                           [jar]
[INFO] 
[INFO] -----------------------------< demo:maven >-----------------------------
[INFO] Building maven 0.0.1-SNAPSHOT                                      [1/4]
[INFO] --------------------------------[ pom ]---------------------------------
[INFO] 
[INFO] ----------------------------< demo:common >-----------------------------
[INFO] Building common 0.0.1-SNAPSHOT                                     [2/4]
[INFO] --------------------------------[ jar ]---------------------------------
[INFO] 
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ common ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /Users/neo/workspace/maven/common/src/main/resources
[INFO] 
[INFO] --- maven-compiler-plugin:3.8.0:compile (default-compile) @ common ---
[INFO] Nothing to compile - all classes are up to date
[INFO] 
[INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ common ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /Users/neo/workspace/maven/common/src/test/resources
[INFO] 
[INFO] --- maven-compiler-plugin:3.8.0:testCompile (default-testCompile) @ common ---
[INFO] Nothing to compile - all classes are up to date
[INFO] 
[INFO] --- maven-surefire-plugin:3.0.0-M3:test (default-test) @ common ---
[INFO] 
[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] 
[INFO] Results:
[INFO] 
[INFO] Tests run: 0, Failures: 0, Errors: 0, Skipped: 0
[INFO] 
[INFO] 
[INFO] --- maven-jar-plugin:2.4:jar (default-jar) @ common ---
[INFO] Building jar: /Users/neo/workspace/maven/common/target/common-0.0.1-SNAPSHOT.jar
[INFO] META-INF/maven/demo/common/pom.xml already added, skipping
[INFO] META-INF/maven/demo/common/pom.properties already added, skipping
[INFO] 
[INFO] ---------------------------< demo:project1 >----------------------------
[INFO] Building project1 0.0.1-SNAPSHOT                                   [3/4]
[INFO] --------------------------------[ jar ]---------------------------------
[INFO] 
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ project1 ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /Users/neo/workspace/maven/project1/src/main/resources
[INFO] 
[INFO] --- maven-compiler-plugin:3.8.0:compile (default-compile) @ project1 ---
[INFO] Nothing to compile - all classes are up to date
[INFO] 
[INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ project1 ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /Users/neo/workspace/maven/project1/src/test/resources
[INFO] 
[INFO] --- maven-compiler-plugin:3.8.0:testCompile (default-testCompile) @ project1 ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 1 source file to /Users/neo/workspace/maven/project1/target/test-classes
[INFO] 
[INFO] --- maven-surefire-plugin:3.0.0-M3:test (default-test) @ project1 ---
[INFO] 
[INFO] --- maven-jar-plugin:2.4:jar (default-jar) @ project1 ---
[INFO] Building jar: /Users/neo/workspace/maven/project1/target/project1-0.0.1-SNAPSHOT.jar
[INFO] META-INF/maven/demo/project1/pom.xml already added, skipping
[INFO] META-INF/maven/demo/project1/pom.properties already added, skipping
[INFO] 
[INFO] ---------------------------< demo:project2 >----------------------------
[INFO] Building project2 0.0.1-SNAPSHOT                                   [4/4]
[INFO] --------------------------------[ jar ]---------------------------------
[INFO] 
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ project2 ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /Users/neo/workspace/maven/project2/src/main/resources
[INFO] 
[INFO] --- maven-compiler-plugin:3.8.0:compile (default-compile) @ project2 ---
[INFO] Nothing to compile - all classes are up to date
[INFO] 
[INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ project2 ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /Users/neo/workspace/maven/project2/src/test/resources
[INFO] 
[INFO] --- maven-compiler-plugin:3.8.0:testCompile (default-testCompile) @ project2 ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 1 source file to /Users/neo/workspace/maven/project2/target/test-classes
[INFO] 
[INFO] --- maven-surefire-plugin:3.0.0-M3:test (default-test) @ project2 ---
[INFO] 
[INFO] --- maven-jar-plugin:2.4:jar (default-jar) @ project2 ---
[INFO] Building jar: /Users/neo/workspace/maven/project2/target/project2-0.0.1-SNAPSHOT.jar
[INFO] META-INF/maven/demo/project2/pom.xml already added, skipping
[INFO] META-INF/maven/demo/project2/pom.properties already added, skipping
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary for maven 0.0.1-SNAPSHOT:
[INFO] 
[INFO] maven .............................................. SUCCESS [  0.006 s]
[INFO] common ............................................. SUCCESS [  2.317 s]
[INFO] project1 ........................................... SUCCESS [  0.539 s]
[INFO] project2 ........................................... SUCCESS [  0.101 s]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  3.115 s
[INFO] Finished at: 2019-02-28T17:03:29+08:00
[INFO] ------------------------------------------------------------------------
neo@MacBook-Pro ~/workspace/maven %

我们可以看到有三个包产生

			
neo@MacBook-Pro ~/workspace/maven % find . -iname '*.jar'
./project1/target/project1-0.0.1-SNAPSHOT.jar
./common/target/common-0.0.1-SNAPSHOT.jar
./project2/target/project2-0.0.1-SNAPSHOT.jar

我们也可以单独编译子项目

			
neo@MacBook-Pro ~/workspace/maven/project1 % mvn package
[INFO] Scanning for projects...
[INFO] 
[INFO] ---------------------------< demo:project1 >----------------------------
[INFO] Building project1 0.0.1-SNAPSHOT
[INFO] --------------------------------[ jar ]---------------------------------
[INFO] 
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ project1 ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /Users/neo/workspace/maven/project1/src/main/resources
[INFO] 
[INFO] --- maven-compiler-plugin:3.8.0:compile (default-compile) @ project1 ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 1 source file to /Users/neo/workspace/maven/project1/target/classes
[INFO] 
[INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ project1 ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /Users/neo/workspace/maven/project1/src/test/resources
[INFO] 
[INFO] --- maven-compiler-plugin:3.8.0:testCompile (default-testCompile) @ project1 ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 1 source file to /Users/neo/workspace/maven/project1/target/test-classes
[INFO] 
[INFO] --- maven-surefire-plugin:3.0.0-M3:test (default-test) @ project1 ---
[INFO] 
[INFO] --- maven-jar-plugin:2.4:jar (default-jar) @ project1 ---
[INFO] Building jar: /Users/neo/workspace/maven/project1/target/project1-0.0.1-SNAPSHOT.jar
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  2.015 s
[INFO] Finished at: 2019-02-28T17:09:18+08:00
[INFO] ------------------------------------------------------------------------

共享库 common-0.0.1-SNAPSHOT.jar 已经安装到 ～/.m2 目录下。

			
neo@MacBook-Pro ~/workspace/maven/project1 % find ~/.m2 -iname 'common-0.0.1-SNAPSHOT.jar'
/Users/neo/.m2/repository/demo/common/0.0.1-SNAPSHOT/common-0.0.1-SNAPSHOT.jar
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23.4. pom.xml 起始页 23.6. 依赖管理