I have two maven projects, the second project extends some classes of first project. I want to create the jar file with all dependencies of first project and include it to another project as dependency. I am searching this since long time, is it possible to do it?
I am new to maven, any help on this would be highly appreciated.
Thanks
If you just want to add the dependencies to another project you add the second project dependency to your new project and the first one will be inherited and automatically included. This is what is called a transitive dependency. Read more about it in the free book Maven: The Complete Reference.
If I understand you right, you want to create a uber-jar containing all dependencies, right ?
Please refer to this question How can I create an executable JAR with dependencies using Maven?
In the second project's POM file, specify the first projects maven co-ordinates (groupId,artifactId,version,packaging) under the 'dependency' section. It will transitively acquire all the dependent artifacts.
Although it is possible in Maven to generate a standalone jar with all its dependencies. For that purpose, you can use the maven-shade-plugin. ( Reference )
There are two ways you are create a fat jar. You include the jar itself in the jar of dependent. You will not have much control in this case and the maven assembly plugin would do the work. Alternatively, you can unzip the jar and zip everything together to create the new jar. You have to decide which one best suits you. If you have multiple versions of same class, then include the whole jar in the new jar would help, but if the versions are coherent, it's best to create a jar by unzipping and zipping everything. For the second procedure, I recommend using the maven shade plugin to create uber jar.
Related
I am trying to convert my existing web app project into maven. I have a bunch of jars in my project manually downloaded and kept in a directory. While converting to maven, I need the name of group id and artifact id of these jars so that I can mention it in pom.xml.
Is there any other way than manually searching for each jar name in mvnrepository.com?
I think you're slightly out of luck. There might be a chance that some of the jars contain the information you're looking for under
META-INF/maven/<groupId>/<artifactId>/pom.properties
But other than that, #JFabianMeier is right, it's manual labor. And please be aware that Maven uses transitive dependencies that may affect your classpath differently than when you specify the jars from a directory.
You might have to add exclusions to your POM's transitive dependencies to get the classpath as you want it.
Want to shift to maven for my old java web project. So created a basic pom.xml using IntelliJ Idea facility. The project is a J2EE web project and also uses axis 2 1.7.7 . All the jars are in 'lib' directory inside the project structure. Is there a easy way to find out the dependency entries which will be required in the newly created 'pom.xml' . What I mean is a a tool which can pickup the jars one by one and suggest the dependency entries
Any help will be highly appreciated here.Thanks
I don't think there is such a tool.
Note that you probably only need to add some of the dependencies because Maven resolves transitive dependencies automatically.
So I would look into the source code, figure out which classes you import and add the appropriate dependencies.
My project inherits it's compile dependencies from parent and I have no control over it - can't change them to provided. Additionally, I have added another dependency 'a:b:1.0.0' to my project's pom. I want to include only 'a:b:1.0.0' with it's own dependencies (recursively ) to my uber jar.
Seems like neither assembly nor shade plugin doesn't support such case.
How this could be done ?
Thanks
Shading recursively has some significant disadvantages. Especially, the problem of duplicate files from multiple dependencies being overwritten with only a single version of the file. This can cause some pretty annoying problems to troubleshoot at runtime. You'd be better off using something like spring boot to build a standalone jar where instead of shading files into a single hierarchy, will embed dependent libraries into itself as a subdirectory and include on the classpath for you.
http://docs.spring.io/spring-boot/docs/current/maven-plugin/repackage-mojo.html
I am currently working in a Java project, and we use maven to build the final jar. There are two ways to build the jars as we all know, i.e. one single jar with-dependencies, and a jar without dependencies. In the latter case, we need to add dependent jars to the classpath as well.
In principle both can work, personally I prefer one jar with dependencies, but in the project team members decided to use separate jar without dependencies. So hereby I would like to know which choice is better?
This question has no answer, since it depends on what you need to do.
If you're writing an utility package or component, that could be a dependency of another project, then there's no point in having all the dependencies inside it - it's better to leave dependency resolution to a dependency manager, like Maven.
If you, instead, are writing a full application packaged as a jar, I mean something with a MainClass that can be executed with java -jar myjar, then having the dependencies together will make distribution easier.
Consider that, for instance, if you're writing a webapp, that'll be packaged as a WAR, it normally comes with dependencies.
Typically, a maven built jar artifact will have it's pom included under META-INF. I recently noticed that the Spring jars don't have this. So, that causes me to wonder about the purpose of that pom.
It seems like maven retrieves the pom directly from the repository when it's doing things that require knowledge of the artifacts meta-data, e.g. when determining dependencies.
So, what's the embedded one for?
The Maven docs suggest two reasons for the pom in this location.
1) Merely for reference, as a convenience. As the docs say, it makes the artifact "self describing"
2) You can get at this information from within your application using Java. This enables the arfiact to auto-report it's version within the application.
http://maven.apache.org/guides/getting-started/index.html
The pom you will find in the repository is not necessarily the one used to build the artifact. It is aimed at the users of the artifact and can be customized when building your artifact.
The one included inside the artifact IS the one used to produce the artifact.
There are options to not have it included in the artifact.