Can you have both maven's and gradle in same java build? - java

We already started our project in mavens(spring mvc) but realized gradle is better for managing big to enterprise level builds like our project. Is there a way to keep mavens but also add on gradle to the same build?
And if yes, how would I add gradle to my existing maven project? thanks.

I guess you need to make a decision:
Invoke maven from gradle
Invoke gradle from maven
If your end goal is to move to gradle then I suggest invoking maven from gradle. It looks like there's a plugin here which will do the job

Related

Maven connection to IDE

I am using Maven to use Postrgres SQL driver. Besides I am using InteliJ IDEA Ultimatre Edition, and, as I understood, Maven is included in Ultimate version initially. Correct me - all I need, is to set dependencies, and connect PostrgeSQL to Java. I am not oblige to Download Maven (except required Dependecie of course, I mean Maven as framework)? Thanks a lot!
When you are creating a new project, choose Maven. After the project is created, you will receive an empty Maven project structure with the pom.xml and a script mvnw of Maven Wrapper, which you can use (instead of mvn) to build your app.
Just add dependencies to the pom.xml and build.
The Maven Wrapper will do the work for you - download Maven into the project subdirectory and use it.

How can i do a gradle publish on teamcity to publish a gradle build that uses the maven plugin?

I have teamcity currently configured to use the maven mojo, to publish the gradle jar as a nexus snapshot with just the gav.
I observe that if i use the maven plugin and do a gradle install in the IDE, i am able to see the generated pom.
1) Can i use this pom to publish the jar in nexus repo in teamcity ? I know that i can do it for a pure maven build by using it's pom.
2) Is there a way to not use this pom, and istead configure teamcity build steps to publish from gradle build directly ?
Gradle can of course take care of the publication. It will leverage the build information to produce a POM file that represents best what is declared in your project.
It will then be trivial to invoke that Gradle task from the Teamcity build.
Have a look at the publishing documentation for details on how to set it up.

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.

Installing a framework without maven or gradle

I try to install Javalin framework for creating an API on my Java project. (old java 8 project without maven, gradle, etc). I would like to install the framework with adding the jars to my build path.
But If I add the main jar file then it needs another dependencies jar , then another one another one another one.. etc.
Is there any simple way to add this to my project and all it's dependencies without any build tool like Maven,etc?
I have tried adding it manually , but each jar has many dependencies that it is almost impossible(?)
Well you could create a Maven project and use it to download the dependencies for you.
Maven dependency plugin might be useful. With it you could just call:
mvn dependency:copy-dependencies
and it will download all your dependencies into target/dependency.
I don't think there's a way, I'm afraid.  Dependency management is the exact problem that build tools like Maven and Gradle were created to solve!
The framework supplier could provide a ‘fat’ jar including all the dependencies; but I'm not aware of any that do, as everyone uses Maven or Gradle (or SBT or Ivy or Grape or Leiningen or Buildr).
I think the only real alternative is to do it manually — which, as you've discovered, can be a horrible and lengthy task if the dependency tree is big.  (And would need redoing with every update.)
So I'd suggest biting the bullet and using Maven if you can.

Maven plugin which calls gradle

Is there a maven plugin available which calls gradle?
It might sound strange, but my company still uses maven and I want to make some experiments with gradle on our jenkins server. :-)

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