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Maven:分模块构建工程

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分模块构建maven工程分析

在企业项目开发过程中 由于项目规模庞大,业务复杂,参与的人员比较多,一般会通过合理的模块拆分将一个大型的项目拆分为N多个小模块,分别进行开发。而且拆分出的模块可以非常容易的被其他模块复用。

常见的拆分方式有两种

第一种:

按照业务模块进行拆分,每个模块拆分成一个maven工程,例如将一个项目分为用户模块、订单模块、购物车模块等,每个模块对应就是一个maven工程

第二种:

按照层进行拆分,例如持久层、业务层、表现层等,每个层对应就是一个maven工程

 

不管是上面哪种拆分方式,通常都会提供一个父工程,将一些公共的代码和配置提取到父工程中进行统一管理和配置。

Maven工程的继承

在Java语言中,类之间是可以继承的,通过继承,子类就可以引用父类中非private的属性和方法。同样,在maven工程之间也可以继承,子工程继承父工程后,就可以使用在父工程中引入的依赖。继承的目的是为了消除重复代码。

被继承的Maven项目中的POM的关键部分定义:

 被继承的maven工程通常称为父工程,父工程的打包方式必须为pom,所以我们区分某个maven工程是否为父工程就看这个工程的打包方式是否为pom

继承的Maven项目中的POM的关键部分:

 继承其他maven父工程的工程通常称为子工程,在pom.xml文件中通过parent标签进行父工程的继承

优点:
父子项目,合理有效的附庸依赖jar包,子项目互相独立,更加便于敏捷开发和独立管理

缺点:
父子项目,项目之间的系统集成性能比较差

eg:

创建父工程:

 

 

 pom.xml文件信息:

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 
 3 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4   xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 5   <modelVersion>4.0.0</modelVersion>
 6 
 7   <groupId>com.jw</groupId>
 8   <artifactId>jw-parent</artifactId>
 9   <version>1.0-SNAPSHOT</version>
10   <packaging>pom</packaging>
11 
12   <name>jw-parent</name>
13   <!-- FIXME change it to the project's website -->
14   <url>http://www.example.com</url>
15 
16   <properties>
17     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
18     <maven.compiler.source>1.8</maven.compiler.source>
19     <maven.compiler.target>1.8</maven.compiler.target>
20     <spring.version>5.3.3</spring.version>
21   </properties>
22 
23   <dependencies>
24     <dependency>
25       <groupId>junit</groupId>
26       <artifactId>junit</artifactId>
27       <version>4.11</version>
28       <scope>test</scope>
29     </dependency>
30     <dependency>
31       <groupId>org.springframework</groupId>
32       <artifactId>spring-context</artifactId>
33       <version>${spring.version}</version>
34     </dependency>
35   </dependencies>
36 
37   <dependencyManagement>
38     <dependencies>
39       <dependency>
40         <groupId>mysql</groupId>
41         <artifactId>mysql-connector-java</artifactId>
42         <version>8.0.22</version>
43       </dependency>
44     </dependencies>
45   </dependencyManagement>
46 
47   <build>
48     <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
49       <plugins>
50         <!-- clean lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#clean_Lifecycle -->
51         <plugin>
52           <artifactId>maven-clean-plugin</artifactId>
53           <version>3.1.0</version>
54         </plugin>
55         <!-- default lifecycle, jar packaging: see https://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_jar_packaging -->
56         <plugin>
57           <artifactId>maven-resources-plugin</artifactId>
58           <version>3.0.2</version>
59         </plugin>
60         <plugin>
61           <artifactId>maven-compiler-plugin</artifactId>
62           <version>3.8.0</version>
63         </plugin>
64         <plugin>
65           <artifactId>maven-surefire-plugin</artifactId>
66           <version>2.22.1</version>
67         </plugin>
68         <plugin>
69           <artifactId>maven-jar-plugin</artifactId>
70           <version>3.0.2</version>
71         </plugin>
72         <plugin>
73           <artifactId>maven-install-plugin</artifactId>
74           <version>2.5.2</version>
75         </plugin>
76         <plugin>
77           <artifactId>maven-deploy-plugin</artifactId>
78           <version>2.8.2</version>
79         </plugin>
80         <!-- site lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#site_Lifecycle -->
81         <plugin>
82           <artifactId>maven-site-plugin</artifactId>
83           <version>3.7.1</version>
84         </plugin>
85         <plugin>
86           <artifactId>maven-project-info-reports-plugin</artifactId>
87           <version>3.0.0</version>
88         </plugin>
89       </plugins>
90     </pluginManagement>
91   </build>
92 </project>

创建子工程:

pom.xml文件信息:

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <project xmlns="http://maven.apache.org/POM/4.0.0"
 3          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 5     <modelVersion>4.0.0</modelVersion>
 6 
 7     <parent>
 8         <groupId>com.jw</groupId>
 9         <artifactId>jw-parent</artifactId>
10         <version>1.0-SNAPSHOT</version>
11         <relativePath>../jw-parent/pom.xml</relativePath>
12     </parent>
13 
14     <groupId>com.jw</groupId>
15     <artifactId>jw-model</artifactId>
16     <version>1.0-SNAPSHOT</version>
17 
18     <dependencies>
19         <dependency>
20             <groupId>mysql</groupId>
21             <artifactId>mysql-connector-java</artifactId>
22         </dependency>
23     </dependencies>
24 
25 </project>

Maven工程的聚合

在maven工程的pom.xml文件中可以使用<modules>标签将其他maven工程聚合到一起,聚合的目的是为了进行统一操作。
例如拆分后的maven工程有多个,如果要进行打包,就需要针对每个工程分别执行打包命令,操作起来非常繁琐。这时就可以使用<modules>标签将这些工程统一聚合到maven工程中,需要打包的时候,只需要在此工程中执行一次打包命令,其下被聚合的工程就都会被打包了。

优点:
项目之间的整体性较高,便于系统集成和维护。

 

创建父工程jw-aggregation,和上面类似;

父工程的 src目录不需要,可以删除

 创建子工程:(Module)

 

 子工程pom文件:

 此时父工程:

 可以创建多个module

 

 对父模块进行编译和打包,会同步对子模块操作:

对jw-aggregation进行compile操作信息:

 1 C:\Java\jdk1.8.0_251\bin\java.exe -Dmaven.multiModuleProjectDirectory=D:\myCode\JavaPro\jw-aggregation -Dmaven.home=D:\workTools\apache-maven-3.6.3 -Dclassworlds.conf=D:\workTools\apache-maven-3.6.3\bin\m2.conf "-Dmaven.ext.class.path=D:\workTools\JetBrains\IntelliJ IDEA 2020.1.3\plugins\maven\lib\maven-event-listener.jar" "-javaagent:D:\workTools\JetBrains\IntelliJ IDEA 2020.1.3\lib\idea_rt.jar=54736:D:\workTools\JetBrains\IntelliJ IDEA 2020.1.3\bin" -Dfile.encoding=UTF-8 -classpath D:\workTools\apache-maven-3.6.3\boot\plexus-classworlds-2.6.0.jar;D:\workTools\apache-maven-3.6.3\boot\plexus-classworlds.license org.codehaus.classworlds.Launcher -Didea.version2020.1.3 -s D:\myCode\mavenConf\settings.xml compile
 2 [INFO] Scanning for projects...
 3 [INFO] ------------------------------------------------------------------------
 4 [INFO] Reactor Build Order:
 5 [INFO] 
 6 [INFO] jw-aggregation                                                     [pom]
 7 [INFO] jw-web                                                             [jar]
 8 [INFO] jw-center                                                          [jar]
 9 [INFO] jw-service                                                         [jar]
10 [INFO] 
11 [INFO] -----------------------< com.jw:jw-aggregation >------------------------
12 [INFO] Building jw-aggregation 1.0-SNAPSHOT                               [1/4]
13 [INFO] --------------------------------[ pom ]---------------------------------
14 [INFO] 
15 [INFO] ---------------------------< com.jw:jw-web >----------------------------
16 [INFO] Building jw-web 1.0-SNAPSHOT                                       [2/4]
17 [INFO] --------------------------------[ jar ]---------------------------------
18 [INFO] 
19 [INFO] --- maven-resources-plugin:3.0.2:resources (default-resources) @ jw-web ---
20 [INFO] Using 'UTF-8' encoding to copy filtered resources.
21 [INFO] skip non existing resourceDirectory D:\myCode\JavaPro\jw-aggregation\jw-web\src\main\resources
22 [INFO] 
23 [INFO] --- maven-compiler-plugin:3.8.0:compile (default-compile) @ jw-web ---
24 [INFO] Changes detected - recompiling the module!
25 [INFO] Compiling 1 source file to D:\myCode\JavaPro\jw-aggregation\jw-web\target\classes
26 [INFO] 
27 [INFO] --------------------------< com.jw:jw-center >--------------------------
28 [INFO] Building jw-center 1.0-SNAPSHOT                                    [3/4]
29 [INFO] --------------------------------[ jar ]---------------------------------
30 [INFO] 
31 [INFO] --- maven-resources-plugin:3.0.2:resources (default-resources) @ jw-center ---
32 [INFO] Using 'UTF-8' encoding to copy filtered resources.
33 [INFO] skip non existing resourceDirectory D:\myCode\JavaPro\jw-aggregation\jw-center\src\main\resources
34 [INFO] 
35 [INFO] --- maven-compiler-plugin:3.8.0:compile (default-compile) @ jw-center ---
36 [INFO] Changes detected - recompiling the module!
37 [INFO] Compiling 1 source file to D:\myCode\JavaPro\jw-aggregation\jw-center\target\classes
38 [INFO] 
39 [INFO] -------------------------< com.jw:jw-service >--------------------------
40 [INFO] Building jw-service 1.0-SNAPSHOT                                   [4/4]
41 [INFO] --------------------------------[ jar ]---------------------------------
42 [INFO] 
43 [INFO] --- maven-resources-plugin:3.0.2:resources (default-resources) @ jw-service ---
44 [INFO] Using 'UTF-8' encoding to copy filtered resources.
45 [INFO] skip non existing resourceDirectory D:\myCode\JavaPro\jw-aggregation\jw-service\src\main\resources
46 [INFO] 
47 [INFO] --- maven-compiler-plugin:3.8.0:compile (default-compile) @ jw-service ---
48 [INFO] Changes detected - recompiling the module!
49 [INFO] Compiling 1 source file to D:\myCode\JavaPro\jw-aggregation\jw-service\target\classes
50 [INFO] ------------------------------------------------------------------------
51 [INFO] Reactor Summary for jw-aggregation 1.0-SNAPSHOT:
52 [INFO] 
53 [INFO] jw-aggregation ..................................... SUCCESS [  0.003 s]
54 [INFO] jw-web ............................................. SUCCESS [  1.279 s]
55 [INFO] jw-center .......................................... SUCCESS [  0.037 s]
56 [INFO] jw-service ......................................... SUCCESS [  0.036 s]
57 [INFO] ------------------------------------------------------------------------
58 [INFO] BUILD SUCCESS
59 [INFO] ------------------------------------------------------------------------
60 [INFO] Total time:  1.466 s
61 [INFO] Finished at: 2021-08-13T00:38:48+08:00
62 [INFO] ------------------------------------------------------------------------

package操作:

 

 install操作:

 

 

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