Java to Maven project conversion related details - java

I am having a java project with a ant build file, using this ant file i create an ejb of the project and deploy it on the jboss server.
Now I am planning to use maven and convert this existing project which consist of nearly 28-30 jar's in its class path(jars related to ejb3, hibernate, jboss, etc).
I can easily do it using eclipse i.e right click project goto maven and click Conver to Maven.
A pom.xml is generated and the MavenClassPath Container is also added to the project.
Now I want to know how to get rid of those 28-30 jar's present in the lib folder of the project and in the classpath. i.e. I want my pom.xml handle all the dependencies.
Does Maven provide any mechanism to achieve this goal while converting the project or I have to add all of these jar dependencies one by one manually in the pom.xml file.
The intention of doing this is I want to have common maven remote repository where the jars will be stored and each developer machine will point to it through their maven project.
Thanks

I think you're after a repository manager like Nexus (I use Nexus, it seems to be the most popular http://nexus.sonatype.org/ ).
Nexus can be used as:
A proxy repository (for Maven Central, etc)
A repository for your own releases.
Nexus provides user management for your developers to release builds into the repo.
Developers will then point their Maven settings.xml file to your Nexus repository, and all their dependencies will come from here (Nexus will cache them).
I'm afraid you will have to configure the dependencies individually, but that is a good thing, because you should pay attention to what version ranges you are interested in for each dependency.
Any jars which can't be found in Maven Central, etc, you can add to your own Nexus repository .
Ofcourse there are alternatives to Nexus, but I haven't used any.
HTH

The most important thing i can recommend is to use a Maven Repository Manager (Nexus, Artifactory or Achiva or other..).
Second your pom conversion via Eclipse shows me that you are not using an up-to-date Eclipse nor an up-to-date Maven Plugin for Eclipse. The best thing would be use Eclipse-Indigo (m2e is the newest and greatest).
Furthermore you have to go through all your jar's and add them step by step to you pom (dependencies) and see if your project can be compiled. This should be checked on command line not inside Eclipse.
After you got a working pom.xml file put it into your version control and check if you can remove some of your added dependencies based on transitive dependencies. After that you can finally delete your lib folder.

Related

Gradle Plugin dependency

What is the exact dependency I need to develop a Gradle Plugin in Java? Ideally I would like to get it from a well-known repository such as Maven Central or similar.
I have a Maven project with a core functionality and I just added two extra plugins, one for Ant, one for Maven. They are already tested and working; easy! Now, I wanted to add a third module for a Gradle plugin to make this functionality also available from any Gradle project.
However, I can't find the exact dependencies I need to develop a Gradle plugin.
The Gradle docs (such as https://docs.gradle.org/current/userguide/java_gradle_plugin.html) are not very well written to say the least. They mention:
the gradleAPI() dependency
or the java-gradle-plugin dependency
But they are quite unclear... no group, no version (really?).
If anyone can enlighten me to where I can get these dependencies from, I would be very thankful.
Gradle's public and internal APIs, aka gradleApi(), are bundled with the Gradle distribution and not independently published and therefore not easily consumable by Maven builds. There's the pending epic #1156 (Ensure plugin cross-version compatibility by allowing a user to depend on gradlePublicApi()) that might help here.
Since Gradle plugins are best to be built with Gradle, a pragmatic solution is to invoke the Gradle build from Maven and attach the produced artifact to the Maven build. Andres Almiray (aalmiray) once described this in the blog post Running Gradle Inside Maven (Web Archive Link). He describes the following high level steps:
Create a new Maven module (e.g. gradle-plugin) and add attach it to the parent POM
In the POM of gradle-plugin add a dependency to your core module. Use the maven-dependency-plugin to store dependencies to the Maven build folder, e.g. target/dependencies.
Create the build.gradle, add a Maven repository that points to target/dependencies (step 2) and let it depend on the core module as well as gradleApi(). Implement the Gradle plugin.
Use the exec-maven-plugin to invoke the Gradle build.
Use the maven-resources-plugin to copy the Gradle built plugin jars to the standard Maven build folder.
Use the build-helper-maven-plugin to attach the copied jars to the Maven build.
Sample project to be found here (gradle-in-maven).
https://docs.gradle.org/current/userguide/custom_plugins.html#sec:custom_plugins_standalone_project
In here it is mentioned that it is gradleApi() and I know that this works (from experience). The localGroovy() on that page is only needed if your plugin code uses groovy (does not apply if you only use groovy in the build.gradle of your plugin).
java-gradle-plugin is a library that makes it a bit simpler to make plugins, it is not required though. I personally prefer using gradleApi only.
EDIT:
It appears I've misunderstood the question. Here are the steps to get gradleApi jar:
Create a Gradle project with your desired Gradle version.
Add implementation gradleApi() dependency.
Import/run the project once.
Go to your .gradle folder (located in home folder in Linux-based operating systems).
Open caches folder
Open the version folder you want, e.g. 6.0.1
Open generated-gradle-jars folder.
Copy the jar to wherever you want and use it.
For me the 6.0.1 jar is at ~/.gradle/caches/6.0.1/generated-gradle-jars/gradle-api-6.0.1.jar
Please note that I have not tested this, I know the jar is there but I haven't tried using it.

How to download list of artifacts from maven nexus repository using Java

I have a Maven Nexus repository that manages several maven projects.Every time build happens on the specific project we send binaries/snap shots to Nexus.There are several ways to access nexus.
Nexus REST API
Aether
My requirement is that how can i fetch available list of artifacts from Nexus repository of a specific project and how can i inject older artifact(downloaded) into a local project when it execute.If any one knows how to do this Please share.I can not find any well documented examples.
If I understand your questions correctly you are looking at creating a runnable application for your Maven project that includes the dependencies.
This can e.g. for a jar project be done with the Maven Assembly Plugin and the jar-with-dependencies descriptor (see http://maven.apache.org/plugins/maven-assembly-plugin/descriptor-refs.html#jar-with-dependencies)

How can I tell Maven to bundle dependent jars

I want to use Jmathplot.jar
I tried to put it as a dependency
<dependency>
<groupId>jmathplot</groupId>
<artifactId>jmathplot</artifactId>
<version>1.0</version>
<scope>system</scope>
<systemPath>${project.basedir}/lib/jmathplot.jar</systemPath>
</dependency>
but when installing I get this error:
Some problems were encountered while building the effective model for com.NResearch:dable-start-tRisk:jar:0.1-SNAPSHOT
[WARNING] 'dependencies.dependency.systemPath' for jmathplot:jmathplot:jar should not point at files within the project directory, ${project.basedir}/lib/jmathplot.jar will be unresolvable by dependent projects # line 44, column 19
How can I get around this please?
EDIT1:
I cannot change Maven to include all dependent jars into a single jar. As this is uploaded to a web project.
"Dependent" is using your project, "dependency" is used by your project.
The real error here is that jmathplot.jar is in a folder that can really only reliably be found by your project. Even though your dependents know how to find your artifact in the local repository, they won't know where the sources are for your artifact, hence won't be able to find lib/jmathplot.jar. You can fix that by changing the systemPath to an absolute path. It can still be parametrized, but then please use properties rather than implicit properties (such as ${project.basedir}.
It'd be better to get rid of the systemPath dependency, by installing jmathplot into a company repository, so it can be used alike 'normal' artifacts. But that may not be a useful option if you have to distribute your artifact out of the reach of your company repository. It would even be better if jmathplot would just get deployed to the Maven central repository.
As a last resort you may choose to bundle the dependencies (not the dependents). You can do this:
Using the Maven Shade Plugin. It lets you choose which packages to include which may be useful to bundle only jmathplot (and not other dependencies).
Using the Maven Assembly Plugin. It has a predefined descriptor for "JAR with dependencies" which would fit your use case. You could create your own descriptor off of that example and set dependencySets.dependencySet.scope=system to only include the system dependencies that are giving you trouble.
Best way is to install your dependency on your local repository. To do this:
1) using project source, install to local repository using mvn install
2) if you don't have source code, install to local repository using this
hope it's help
nota: you are spamming around this question, do you ? (see here: JMathPlot what is the Maven dependency code please )

Configure Maven To Create An Archive File With All Dependencies Defined in POM XML

I am working in a private network which doesn't have internet proxy.
I can not create a local repository as well which involves the bureaucracy, management won't allow it. I may be a long term fix but not the solution for the question I asked.
I can not keep maven as a build tool as it requires the direct or indirect internet connection.
I HAVE to use ANT for building the project hence using maven in offline mode also not an option for me.
But I still want to use the maven dependency management for collecting all the jars in a one archive smartly.
My plan is to generate a ZIP file containing dependencies resolved using maven. And then we will share this ZIP file to all developers working inside a private network which doesn't have internet connection.
To do so I will get a temporary access to a computer which is having internet connection and from there I will define a dummy POM with all the dependencies required.
Now the question is how do I generate a ZIP file ( not a single jar ) using maven which contains all the dependencies defined in POM.
while what youre suggesting is technically possible, it is (in my opinion) not the best solution to your problem.
your statement that
it requires the direct or indirect internet connection
is not accurate. what maven requires is a maven repository (or a set of them) to fetch stuff from. the best solution to your problem would be to install a local maven repository inside your organization's network. the 2 most popular choices for a loaclly-run maven repository seem to be nexus and artifactory - both offer free open source versions and paid supported pro versions.
once you set up a maven repository inside your organization's network and populate it with the artifacts you require you can simply configure all of your project's pom files to go to those repositories. for example, to configure maven to use your repo instead of maven central, you can do this:
<repositories>
<!-- override central -->
<repository>
<id>central</id>
<url>http://your.repo.location</url>
</repository>
</repositories>
you will need to map a plugin repository in a similar fashion.
its also possible to achieve this by configuring the maven settings.xml file in each user's home directory if you dont want this in the pom files but from my experience its less error-prone this way
use following command to build Maven project offline.
mvn -o package
Refer this and this for more information.
I ended up with a smart hack which lets me do dependency resolution and archiving!
I am creating a dummy maven web project with all the dependencies defined in pom xml.
Now the war packaging mode is used by default for web applications.
I simply install the maven project from internet facing machine.
I get all the dependencies and transitive dependencies in war file's "lib" directory with dependency naming version remaining unchanged !!!!
Copying and adding those files into an ANT project is a trivial task then..!

Maven dependency for aqapi13.jar

I am upgrading a project from Ant to Gradle. The project uses a aqapi13.jar(this is oracle aq jar. This is needed as the project reads from an oracle-queue and writes to an activemq queue.)
The ant project contains the jar aqapi13.jar in the libs folder. But iam trying to get this dependency from a repository instead of having it in the libs folder.
However, iam not able to find a repository which contains this jar. All the repositories that I have seen contain aqapi13-9i.jar, but not aqapi13.jar.
Anyone knows the difference between aqapi13.jar and aqapi13-9i.jar and how to get the needed aqapi13.jar from a repository.
Advance Thanks
Some dependencies are never found in public repositories because of the license they have.
One way to use this dependencies is to create your own repository (e.g. artifactory, nexus, archiva). Then you are free to put in every artifact you want (as long as you do not publish the repository). This repository can also serve as a mirror for maven.
Another way could be to mark this dependency as system scope.

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