使用Maven Assembly插件管理多模块依赖项

Question

我使用maven组装插件为我的多模块项目创建一个程序集。该多模块项目中构建了两个单独的应用程序，每个项目都具有单独的依赖项。我制作了一个自定义程序集描述符，它使用模块构建和它们各自的依赖项组装两个目录（针对每个应用程序）。它确实很好，但有一件事 - 它将两个模块的依赖性给彼此的组装施加了依赖关系。

以下是我项目的简化版本，具有完全相同的行为。

考虑一个由两个模块和装配模块组成的项目：

APP
  module1
  module2
  assembly

.

我纯粹添加了依赖项进行演示：

com.test.app:module1:jar:1.0
\- commons-cli:commons-cli:jar:1.2:compile

com.test.app:module2:jar:1.0
\- commons-daemon:commons-daemon:jar:1.0.8:compile

.

这是父pom：

<project>
  <modelVersion>4.0.0</modelVersion>

  <groupId>com.test</groupId>
  <artifactId>app</artifactId>
  <version>1.0</version>
  <packaging>pom</packaging>

  <modules>
    <module>module1</module>
    <module>module2</module>
    <module>assembly</module>
  </modules>
</project>

.

module1 pom：

<project>
  <parent>
    <groupId>com.test</groupId>
    <artifactId>app</artifactId>
    <version>1.0</version>
  </parent>

  <modelVersion>4.0.0</modelVersion>

  <groupId>com.test.app</groupId>
  <artifactId>module1</artifactId>
  <version>1.0</version>
  <packaging>jar</packaging>

  <dependencies>
    <dependency>
      <groupId>commons-cli</groupId>
      <artifactId>commons-cli</artifactId>
      <version>1.2</version>
    </dependency>
  </dependencies>
</project>

.

module2 pom：

<project>
  <parent>
    <groupId>com.test</groupId>
    <artifactId>app</artifactId>
    <version>1.0</version>
  </parent>

  <modelVersion>4.0.0</modelVersion>

  <groupId>com.test.app</groupId>
  <artifactId>module2</artifactId>
  <version>1.0</version>
  <packaging>jar</packaging>

  <dependencies>
    <dependency>
      <groupId>commons-daemon</groupId>
      <artifactId>commons-daemon</artifactId>
      <version>1.0.8</version>
    </dependency>
  </dependencies>
</project>

.

装配pom：

<project>
  <parent>
    <groupId>com.test</groupId>
    <artifactId>app</artifactId>
    <version>1.0</version>
  </parent>

  <modelVersion>4.0.0</modelVersion>

  <groupId>com.test.app</groupId>
  <artifactId>assembly</artifactId>
  <version>1.0</version>
  <packaging>pom</packaging>

  <build>
    <plugins>
      <plugin>
        <artifactId>maven-assembly-plugin</artifactId>
        <version>2.2.2</version>

        <executions>
          <execution>
            <id>make-assembly</id>
            <phase>package</phase>

            <goals>
              <goal>single</goal>
            </goals>
          </execution>
        </executions>

        <configuration>
          <appendAssemblyId>false</appendAssemblyId>

          <descriptors>
            <descriptor>src/main/assembly/descriptor.xml</descriptor>
          </descriptors>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project>

.

最后，装配描述符：

<assembly>
  <id>distribution</id>
  <includeBaseDirectory>false</includeBaseDirectory>

  <formats>
    <format>dir</format>
  </formats>

  <moduleSets>
    <moduleSet>
      <useAllReactorProjects>true</useAllReactorProjects>

      <includes>
        <include>com.test.app:module1:jar</include>
      </includes>

      <binaries>
        <outputDirectory>module1</outputDirectory>
        <unpack>false</unpack>

        <dependencySets>
          <dependencySet>
            <unpack>false</unpack>
          </dependencySet>
        </dependencySets>
      </binaries>
    </moduleSet>

    <moduleSet>
      <useAllReactorProjects>true</useAllReactorProjects>

      <includes>
        <include>com.test.app:module2:jar</include>
      </includes>

      <binaries>
        <outputDirectory>module2</outputDirectory>
        <unpack>false</unpack>

        <dependencySets>
          <dependencySet>
            <unpack>false</unpack>
          </dependencySet>
        </dependencySets>
      </binaries>
    </moduleSet>
  </moduleSets>
</assembly>

.

可以看到，程序集与包阶段绑定。所以，当我执行时

mvn package

.

从父目录中，我有以下装配

module1/
  commons-cli-1.2.jar
  commons-daemon-1.0.8.jar
  module1-1.0.jar
module2/
  commons-cli-1.2.jar
  commons-daemon-1.0.8.jar
  module2-1.0.jar

.

基本上，这里的问题是模块1不依赖于Commons-守护程序，但程序集插件已经包括依赖。同样，使用模块2和Commons-Cli。

有人可以解释为什么装配插件的行为如何？

一个解决方案？

Answer 1

I've always had similar experiences using the assembly plugin with multi-module projects where the end result wasn't what I expected. I hope someone else can provide a more accurate answer as to why that's happening and how best to use those two concepts in tandem.

That said, a possible work-around would be to have module1 and module2 generate their own assembly artifacts which contain their respective jars and dependencies. Then you can modify the assembly sub-module pom file to have dependencies on the generated distribution artifacts from its sibling modules and then unpack those into a new assembly.

In both Module1 and Module2's pom files you can add an assembly plugin configuration to your package phase much like you did with the assembly sub-module.

  <build>
    <plugins>
      <plugin>
        <artifactId>maven-assembly-plugin</artifactId>
        <version>2.2.2</version>

        <executions>
          <execution>
            <id>make-assembly</id>
            <phase>package</phase>
            <goals>
              <goal>single</goal>
            </goals>
          </execution>
        </executions>

        <configuration>
          <descriptors>
            <descriptor>src/main/assembly/descriptor.xml</descriptor>
          </descriptors>
        </configuration>
      </plugin>
    </plugins>
  </build>

Module1 would have a src/main/assembly/descriptor.xml like this

<assembly>
  <id>distribution</id>
  <includeBaseDirectory>false</includeBaseDirectory>

  <formats>
    <format>zip</format>
  </formats>

  <dependencySets>
    <dependencySet>
      <outputDirectory>module1</outputDirectory>
      <unpack>false</unpack>
    </dependencySet>
  </dependencySets>
</assembly>

And Module2 will have a similar src/main/assembly/descriptor.xml

<assembly>
  <id>distribution</id>
  <includeBaseDirectory>false</includeBaseDirectory>

  <formats>
    <format>zip</format>
  </formats>

  <dependencySets>
    <dependencySet>
      <outputDirectory>module2</outputDirectory>
      <unpack>false</unpack>
    </dependencySet>
  </dependencySets>
</assembly>

Then in the assembly/pom.xml you would add the Module 1 and 2 zip artifacts as dependencies

  <dependencies>
    <dependency>
      <groupId>com.test.app</groupId>
      <artifactId>module1</artifactId>
      <version>1.0</version>
      <type>zip</type>
      <classifier>distribution</classifier>
    </dependency>
    <dependency>
      <groupId>com.test.app</groupId>
      <artifactId>module2</artifactId>
      <version>1.0</version>
      <type>zip</type>
      <classifier>distribution</classifier>
    </dependency>
  </dependencies>

...and trim up the assembly/src/main/assembly/descriptor.xml file to look like this

<assembly>
  <id>distribution</id>
  <includeBaseDirectory>false</includeBaseDirectory>

  <formats>
    <format>dir</format>
  </formats>

  <dependencySets>
    <dependencySet>
      <useTransitiveDependencies>false</useTransitiveDependencies>
      <unpack>true</unpack>
    </dependencySet>
  </dependencySets>

</assembly>

Like I said this would be one possible work around and unfortunately adds a significant amount of additional XML configuration to your build process. But it works.