Hi, All!
I have a maven2 project, consisting of root project (with pom packaging) and a set of modules having dependencies on each other. The project is a library with a set of apps built on top of this library. Now the problem.
My library uses some resources which cannot be packed in jar - namely some sqlite databases, and I can't find a way to put it near the jar instead of inside it, and to buldle library this way to dependent applications.
Thanks. Any ideas?
Sounds like you could use the maven assembly plugin to create a distribution file of your choice (zip, jar, tar...) which would include the extra resources.
Create a custom assembly to distribute the project as an archive (e.g. a zip or tar.gz) is clearly the way to go here.
To customize the way the Assembly Plugin creates your assemblies, you'll need to provide your custom descriptor (this gives you all the flexibility you need). Then, to build the assembly as part of the build, all you have to do is to bind the single or single-directory mojos into the default build lifecycle as explained in the Configuration and Usage of the plugin's documentation.
Another great resource is Sonatype's book which has an entire chapter dedicated to assemblies: see Chapter 14. Maven Assemblies .
Here is the important fact from Maven: The Complete Reference's Assemblies Chapter Section 8.3.2:
When you generate assemblies as part of your normal build process, those assembly archives will be attached to your main project’s artifact. This means they will be installed and deployed alongside the main artifact, and are then resolvable in much the same way. Each assembly artifact is given the same basic coordinates (groupId, artifactId, and version) as the main project. However, these artifacts are attachments, which in Maven means they are derivative works based on some aspect of the main project build. To provide a couple of examples, source assemblies contain the raw inputs for the project build, and jar-with-dependencies assemblies contain the project’s classes plus its dependencies. Attached artifacts are allowed to circumvent the Maven requirement of one project, one artifact precisely because of this derivative quality.
Since assemblies are (normally) attached artifacts, each must have a classifier to distinguish it from the main artifact, in addition to the normal artifact coordinates. By default, the classifier is the same as the assembly descriptor’s identifier. When using the built-in assembly descriptors, as above, the assembly descriptor’s identifier is generally also the same as the identifier used in the descriptorRef for that type of assembly.
It is important to understand that while most Maven projects only generate a single artifact it is possible to generate more than one and use the classifier coordinate to associate these artifacts with the same GAV coordinate. In your case, you'll want to attach an assembly plugin's "single" goal using something similar to this:
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<version>2.2-beta-2</version>
<dependencies>
<dependency>
<groupId>org.sonatype.mavenbook.assemblies</groupId>
<artifactId>web-fragment-descriptor</artifactId>
<version>1.0-SNAPSHOT</version>
</dependency>
</dependencies>
<executions>
<execution>
<id>assemble</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
<configuration>
<descriptorRefs>
<descriptorRef>web-fragment</descriptorRef>
</descriptorRefs>
</configuration>
</execution>
</executions>
</plugin>
You can attach as many of these executions as you wish, but once you have more than one execution for a particular plugin, each execution will require a unique "id" element. The "single" goal in the Maven Assembly plugin does the same thing that that the "assembly" goal does except it was designed to be bound to the lifecycle.
The other part of you question is about excluding specific resources from a JAR, you can accomplish this by excluding resources in your POM.