Using Gradle to include my own Java library in a project - java

Disclaimer: I'm very new to Gradle and Dependency Management. I tried reading the documentation but just couldn't get through the sheer amount of information. I also couldn't find anything useful to answer my question, so sorry if this has been answered before, I tried searching...
So my situation is as follows: I have one Java project that's supposed to give me a standardized way of using program configurations using JSON files. This project has a dependency on Gson. So far so good, I simply added compile 'com.google.code.gson:gson:2.6.2' to that projects dependencies and all's fine, the library shows up as External Library in Idea, and I can use it and stuff.
Now I want to use that project in other projects to make use of the configuration stuff. And I can not for the life of me figure out how to add the project or the library jar to other projects using Gradle.
I tried things like copying the library jar to the libs folder of the projects to use it in and adding compile files('./libs/myLibrary-0.0.1.jar') to the dependencies list, or adding the jar as a library via the Project Structure thing in Idea. None of these methods worked, and I'm at my wits end.
Any help would be appreciated.

If you or your company have a central binary repository, such as artifactory. Then you should set up publishing your jar there.
But since you haven't mentioned a central repository, I'll assume that you don't have one, and are simply trying to get your dependency to work on a single machine. In that case, what I suggest doing is this:
Add the maven-publish plugin to your dependency project:
apply plugin: 'maven-publish'
Also make sure that you define the group, version and name variables of your project (see here). You'll need them later. Then add a publishing definition that will tell maven-publish to publish all classes:
publishing {
publications {
mavenJava(MavenPublication) {
from components.java
}
}
}
Using these settings you should now be able to run the publishToMavenLocal task. Do it. If successful, the dependency jar should now be in your local maven repository (~/.m2/repository)
Now, add mavenLocal as a repository in the project that needs the dependency:
repositories {
mavenLocal()
}
(you might want to add additional repositories here, such as mavenCentral())
Also add your jar's group, name, and version just like your gson dependency:
compile 'yourgrou:yourname:yourversion.
Gradle should now be able to fetch the dependency from the local maven repo.

You have couple of options. First and easy is to build your base project and available in your local maven repository and use it. To make your project available is your local maven repo, use maven plugin. In your build.gradle file, add the following.
apply plugin: 'maven'
Now use gradle clean build install to publish the jar to your local repo. Remember that install task is the one actually put your jar into your local.Then head over to your other project which depends on this one and tell it to look into your local maven repo by adding mavenLocal to the repositories.
repositories {
mavenCentral()
mavenLocal()
}
Another option is, if you are using centralized repo in your company, you can publish your base jar and use it in the other project. Check out the documentation.

Related

Build JAR with a dependency from the custom repository

I'm trying to build a JAR artifact which requires a custom dependency from the bintray repository, like:
https://dl.bintray.com/foo/bar
Is it possible to instruct the project that consumes such a library that it should resolve dependencies in the extra repository?
Or should I take another approach to provide it?
TL;DR
Build a fat jar including your dependencies.
Long Version
Yes, it is potentially possible to instruct a project that consumes your Gradle plugin to download plugin dependencies from a non-default repository. But it requires the user intervention which is probably not what you want to hear.
The following settings.gradle should retrieve your plugin from the Gradle Plugin Portal and resolve the dependencies from your Bintray repository:
pluginManagement {
repositories {
maven {
url 'https://dl.bintray.com/foo/bar'
}
gradlePluginPortal()
}
}
This is documented under Plugin Management.
Please note that I'm a bit vague in my answer since I never did something similar. What I can tell is that the spring-cloud-contract plugin does exactly this for snapshot versions.
IMHO, in your specific case, you get the best user experience by building a fat jar that includes your dependencies. A remarkable companion being the Gradle Shadow Plugin. It also features additional functionality for Gradle plugins, should you ever need them.

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 use a parent in Gradle across different projects? [duplicate]

At my work we use Maven. I am going to try gradle for the first time. We use a common parent pom for all project which has setting for commonly used maven plugins and few comon dependencies. Is there a similar option available in gradle?
My second question is regarding release management. We use maven release plugin, which works pretty good for us. Is there something similar available in Gradle?
To share stuff within multiple projects of the same build, use allprojects { ... }, subprojects { ... }, etc. Also, extra properties (ext.foo = ...) declared in a parent project are visible in subprojects. A common idiom is to have something like ext.libs = [junit: "junit:junit:4.11", spring: "org.springframework:spring-core:3.1.0.RELEASE", ...] in the top-level build script. Subprojects can then selectively include dependencies by their short name. You should be able to find more information on this in the Gradle Forums.
To share logic across builds, you can either write a script plugin (foo.gradle), put it up on a web server, and include it in builds with apply from: "http://...", or write a binary plugin (a class implementing org.gradle.api.Plugin), publish it as a Jar to a repository, and include it in builds with apply plugin: ... and a buildscript {} section. For details, see the Gradle User Guide and the many samples in the full Gradle distribution.
A current limitation of script (but not binary) plugins is that they aren't cached. Therefore, a build will only succeed if it can connect to the web server that's serving the plugin.
As to your second question (which should have been a separate question), there are a couple of third-party release plugins available, for example https://github.com/townsfolk/gradle-release.
The io.spring.dependency-management plugin allows you to use a Maven bom to control your build's dependencies:
buildscript {
repositories {
mavenCentral()
}
dependencies {
classpath "io.spring.gradle:dependency-management-plugin:0.5.3.RELEASE"
}
}
apply plugin: "io.spring.dependency-management"
Next, you can use it to import a Maven bom:
dependencyManagement {
imports {
mavenBom 'io.spring.platform:platform-bom:1.1.1.RELEASE'
}
}
Now, you can import dependencies without specifying a version number:
dependencies {
compile 'org.springframework:spring-core'
}
I think the best way to do things like maven parent pom is to to use gradle "apply from".
Something like this:
allprojects { // or: subprojects { ... }
apply from: "gradle/script/common.gradle"
}
The link and be a related path or an URL. Hope it helps.
Reference:
Import a Gradle script from the root into subprojects
Super POM, Parent POM type of hierarchy management in Gradle
I too wanted this type of feature, I have created a plugin to provide this here: https://github.com/boxheed/gradle-pater-build-plugin
You can convert the Parent pom content in to Gradle init file very easily.
Gradle init script provides same functionality as Maven super/parent pom. The basic difference is that you can call init script
Run time
As many as of them This gives us flexibility to change the init
script on run time but doubt of not tracking the changes.
You need to take repository, distribution management, profiling and other checks like findbugs, checkstyle etc in to init script.
The detail is huge, You can find complete information here by me.
http://www.scmtechblog.net/2015/12/how-to-migrate-parent-pom-from-maven-to.html
I have explained about gradle release plugin which is similar to maven release plugin.
to achive your goal you could apply the concept of 'multiproject build' explained in the gradel user guide here
Basically you can create an umbrella project which define a set of common configurations by creating a gradle.build file and a gradle.settings file.
The build file contains the properties, dependencies and plugins commons to all projects, the settings.gradle defines what subprojects inherits those configurations.
Moreover, to have an idea of the gradle plugin ecosystem you could check this source.
It is currently not possible, if you want the parent to be cached locally and stored in a Maven repository.
I have added feature request here:
http://forums.gradle.org/gradle/topics/support_for_gradle_parent_shared_between_projects_cached_locally

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.

How to configure gradle to use a local repository only for certain dependency groups?

Working off the gradle dependency docs, we have a build.gradle with snippets like this.
repositories {
mavenCentral()
ivy {
name = 'localRepo'
artifactPattern "http://localRepo.com/[organisation]/[module]/[revision]/[artifact]-[revision].[ext]"
}
}
dependencies {
compile group: 'localRepo', name: 'my-private-library', version: '2.5'
}
This setup does download everything correctly, but I would like to tweak it so that things in group localRepo are only attempted to be pulled from the ivy repository and localRepo is only used for group localRepo. localRepo only holds private jars so we do not want it to be used as the first repo and we do not want to spend a long time querying mavenCentral for jars that will not exist.
Basically I would like to say in the dependency to use a specific repo or that the local ivy repo is only to be used for specific groups. Is there an easy way to do this?
Not quite what you want, but we set up our repositories so that developers get all dependencies from the local private repo, and that local private repo caches the maven central repo. This is faster, as dependencies are only pulled once from maven central by the first developer to access them, and also allows you to see what artifacts are being used in your company. Nexus and artifactory and I am sure all other repositories do as well.
Looks like something similar was asked on the gradle mailing list and the best option currently available is indeed to turn to artifcatory and manage your own shared repository.
It's currently not possible, but it's an open request http://issues.gradle.org/browse/GRADLE-1066

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