maven - 如何为maven父项目生成jar

Question

Maven 需要一个父项目

<packaging>pom</packaging>

父 pom.xml 中的子句。安装这样的项目时，只有一个 pom-file 生成到 maven 存储库中。无论父项目是否有 Java 代码，都不会生成 jar 文件。这迫使我有额外的空父项目，这是矫枉过正。从逻辑上讲，我的一些图书馆可能同时是父母。

有没有办法为父项目生成 pom 和 jar 文件，而无需packaging在安装之间删除/添加子句？

Answer 1

使用 Maven Jar Plugin 和 Maven Build Helper。示例 POM：

<?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>test</groupId>
  <artifactId>test</artifactId>
  <version>1.0</version>

  <packaging>pom</packaging>

  <build>
    <plugins>
      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>build-helper-maven-plugin</artifactId>
        <version>1.7</version>
        <executions>
          <execution>
            <id>attach-artifacts</id>
            <phase>package</phase>
            <goals>
              <goal>attach-artifact</goal>
            </goals>
            <configuration>
              <artifacts>
                <artifact>
                  <file>test-${project.version}</file>
                  <type>jar</type>
                </artifact>
              </artifacts>
            </configuration>
          </execution>
        </executions>
      </plugin>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-jar-plugin</artifactId>
        <version>2.4</version>
        <executions>
          <execution>
            <id>default</id>
            <goals>
              <goal>jar</goal>
            </goals>
            <phase>package</phase>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
</project>

Maven 构建结果：

mvn install
[INFO] Scanning for projects...
[INFO]                                                                         
[INFO] ------------------------------------------------------------------------
[INFO] Building test 1.0
[INFO] ------------------------------------------------------------------------
[INFO] 
[INFO] --- build-helper-maven-plugin:1.7:attach-artifact (attach-artifacts) @ test ---
[INFO] 
[INFO] --- maven-jar-plugin:2.4:jar (default) @ test ---
[WARNING] JAR will be empty - no content was marked for inclusion!
[INFO] 
[INFO] --- maven-install-plugin:2.3.1:install (default-install) @ test ---
[INFO] Installing /home/username/projects/test/pom.xml to /home/username/.m2/repository/test/test/1.0/test-1.0.pom
[INFO] Installing /home/username/projects/test/test-1.0 to /home/username/.m2/repository/test/test/1.0/test-1.0.jar
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 0.805s
[INFO] Finished at: Thu Sep 06 13:33:20 EDT 2012
[INFO] Final Memory: 4M/119M
[INFO] ------------------------------------------------------------------------

关于 Maven 实践的说明：

Parent modules are typically where you define the dependencies and plugins used in common by all your child modules. It rarely has output of its own. You probably want to have a "distribution" sub-module that aggregates all your other module artifacts, rather than attempting to do it in the parent module.