maven的聚合模块和pom继承使用

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下载

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 下载

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>4.0.0modelVersion>

4. <groupId>com.sohu.traingroupId>

5. <artifactId>maven-aggregateartifactId>

6. <version>0.0.1-SNAPSHOTversion>

7. <packaging>pompackaging>

9. <modules>

10. <module>../maven-01module>

11. <module>../maven-02module>

12. <module>..maven-03module>

13. modules>

14. project>

对 maven-aggregate执行下mvn clean compile

Xml代码 下载

1. [INFO] Scanning for projects...

2. [WARNING]

3. [WARNING] Some problems were encountered while building the effective model for com.sohu.train:maven-02:jar:1.0-SNAPSHORT

4. [WARNING] 'dependencies.dependency.exclusions.exclusion.groupId' for junit:junit:jar is missing. @ line 38, column 16

5. [WARNING] 'dependencies.dependency.exclusions.exclusion.artifactId' for junit:junit:jar is missing. @ line 38, column 16

6. [WARNING]

7. [WARNING] It is highly recommended to fix these problems because they threaten the stability of your build.

8. [WARNING]

9. [WARNING] For this reason, future Maven versions might no longer support building such malformed projects.

10. [WARNING]

11. [INFO] ------------------------------------------------------------------------

12. [INFO] Reactor Build Order: //构建 maven 的反应堆，执行清理 编译的顺序

13. [INFO]

14. [INFO] maven-02

15. [INFO] maven-01

16. [INFO] maven-03

17. [INFO] maven-aggregate

18. [INFO]

19. [INFO] ------------------------------------------------------------------------

20. [INFO] Building maven-02 1.0-SNAPSHORT

21. [INFO] ------------------------------------------------------------------------

22. [INFO]

23. [INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ maven-02 ---

24. [INFO] Deleting E:\train\test\maven-02\target

25. [INFO]

26. [INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ maven-02 ---

27. [INFO] Using 'UTF-8' encoding to copy filtered resources.

28. [INFO] skip non existing resourceDirectory E:\train\test\maven-02\src\main\resources

29. [INFO]

30. [INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ maven-02 ---

31. [INFO] Changes detected - recompiling the module!

32. [INFO] Compiling 1 source file to E:\train\test\maven-02\target\classes

33. [INFO]

34. [INFO] ------------------------------------------------------------------------

35. [INFO] Building maven-01 1.0-SNAPSHOT

36. [INFO] ------------------------------------------------------------------------

37. [INFO]

38. [INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ maven-01 ---

39. [INFO] Deleting E:\train\test\maven-01\target

40. [INFO]

41. [INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ maven-01 ---

42. [INFO] Using 'UTF-8' encoding to copy filtered resources.

43. [INFO] Copying 1 resource

44. [INFO]

45. [INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ maven-01 ---

46. [INFO] Changes detected - recompiling the module!

47. [INFO] Compiling 1 source file to E:\train\test\maven-01\target\classes

48. [INFO]

49. [INFO] ------------------------------------------------------------------------

50. [INFO] Building maven-03 0.0.1-SNAPSHOT

51. [INFO] ------------------------------------------------------------------------

52. [INFO]

53. [INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ maven-03 ---

54. [INFO] Deleting E:\train\test\maven-03\target

55. [INFO]

56. [INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ maven-03 ---

57. [INFO] Using 'UTF-8' encoding to copy filtered resources.

58. [INFO] skip non existing resourceDirectory E:\train\test\maven-03\src\main\resources

59. [INFO]

60. [INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ maven-03 ---

61. [INFO] Changes detected - recompiling the module!

62. [INFO] Compiling 1 source file to E:\train\test\maven-03\target\classes

63. [INFO]

64. [INFO] ------------------------------------------------------------------------

65. [INFO] Building maven-aggregate 0.0.1-SNAPSHOT

66. [INFO] ------------------------------------------------------------------------

67. [INFO]

68. [INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ maven-aggregate ---

69. [INFO] ------------------------------------------------------------------------

70. [INFO] Reactor Summary: // 可以看到 对3个maven项目 一起执行编译

71. [INFO]

72. [INFO] maven-02 ........................................... SUCCESS [ 1.874 s]

73. [INFO] maven-01 ........................................... SUCCESS [ 0.108 s]

74. [INFO] maven-03 ........................................... SUCCESS [ 0.158 s]

75. [INFO] maven-aggregate .................................... SUCCESS [ 0.002 s]

76. [INFO] ------------------------------------------------------------------------

77. [INFO] BUILD SUCCESS

78. [INFO] ------------------------------------------------------------------------

79. [INFO] Total time: 2.263 s

80. [INFO] Finished at: 2016-01-15T14:35:41+08:00

81. [INFO] Final Memory: 14M/227M

82. [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：下载

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

下载

2.2 pom标签配置-parent,*Management

1.常用的pom被继承的元素

Xml代码 下载

1. groupId ：项目组 ID ，项目坐标的核心元素；

2. version ：项目版本，项目坐标的核心元素；

3. description ：项目的描述信息；

4. properties ：自定义的 Maven 属性；

5. dependencies ：项目的依赖配置；

6. dependencyManagement ：醒目的依赖管理配置；

7. repositories ：项目的仓库配置；

8. 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 下载

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>4.0.0modelVersion>

4. <groupId>com.sohu.traingroupId>

5. <artifactId>maven-aggregateartifactId>

6. <version>0.0.1-SNAPSHOTversion>

7. <packaging>pompackaging>

9. <modules>

10. <module>../maven-01module>

11. <module>../maven-02module>

12. <module>../maven-03module>

13. modules>

15. <properties>

16. <junit.version>3.8.1junit.version>

17. properties>

19. <dependencyManagement>

20. <dependencies>

21. <dependency>

22. <groupId>junitgroupId>

23. <artifactId>junitartifactId>

24. <version>${junit.version}version>

25. <scope>testscope>

26. dependency>

27. dependencies>

28. dependencyManagement>

29. 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 下载

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>4.0.0modelVersion>

5. <parent>

6. <groupId>com.sohu.traingroupId>

7. <artifactId>maven-aggregateartifactId>

8. <version>0.0.1-SNAPSHOTversion>

9. <relativePath>../maven-aggregate/pom.xmlrelativePath>

10. parent>

11. <artifactId>maven-03artifactId>

12. <packaging>jarpackaging>

14. <dependencies>

15. <dependency>

16. <groupId>junitgroupId>

17. <artifactId>junitartifactId>

18. dependency>

19. dependencies>

20. project>

这样就完成pom的继承，讲公用的jar一次配置，就可以实现多处引用了。