Gradle + Eclipse : use class from existing project in a new project - java

I know there are a lot of questions that seem similar. I have also spent a few hours getting to grips with Gradle multiprojects. But I still don't understand what the best course of action is here. Incidentally I am using Groovy as my coding language, but explanations referencing Java would be just as good.
I have developed an Eclipse Gradle project, "ProjectA", which in particular has a class, IndexManager, which is responsible for creating and opening and querying Lucene indices.
Now I am developing a new Eclipse Gradle project, "ProjectB", which would like to use the IndexManager class from ProjectA.
This doesn't really mean that I would like both projects to be part of a multiproject. I don't want to compile the latest version of ProjectA each time I compile ProjectB - instead I would like ProjectB to be dependent on a specific version of ProjectA's IndexManager. With the option of upgrading to a new version at some future point. I.e. much as with the sorts of dependencies you get from Maven or JCenter...
Both projects have the application plugin, so ProjectA produces an executable .jar file whose name incorporates the version. But currently this contains only the .class files, the resource files, and a file called MANIFEST.MF containing the line "Manifest-Version: 1.0". Obviously it doesn't contain any of the dependencies (e.g. Lucene jar files) needed by the .class files.
The application plugin also lets you produce a runnable distribution: this consists of an executable file (2 in fact, one for *nix/Cygwin, one for Windows), but also all the .jar dependencies needed to run it.
Could someone explain how I might accomplish the task of packaging up this class, IndexManager (or alternatively all the classes in ProjectA possibly), and then including it in my dependencies clause of ProjectB's build.gradle... and then using it in a given file (Groovy or Java) of ProjectB?
Or point to some tutorial about the best course of action?

One possible answer to this which I seem to have found, but find a bit unsatisfactory, appears to be to take the class which is to be used by multiple projects, here IndexManager, and put it in a Gradle project which is specifically designed to be a Groovy library. To this end, you can kick it off by creating the project directory and then:
$ gradle init --type groovy-library
... possible to do from the Cygwin prompt, but not from within Eclipse as far as I know. So you then have to import it into Eclipse. build.gradle in this library project then has to include the dependencies needed by IndexManager, in this case:
compile 'org.apache.lucene:lucene-analyzers-common:6.+'
compile 'org.apache.lucene:lucene-queryparser:6.+'
compile 'org.apache.lucene:lucene-highlighter:6.+'
compile 'commons-io:commons-io:2.6'
compile 'org.apache.poi:poi-ooxml:4.0.0'
compile 'ch.qos.logback:logback-classic:1.2.1'
After this, I ran gradle jar to create the .jar which contains this IndexManager class, initially without any fancy stuff in the manifest (e.g. name, version). And I put this .jar file in a dedicated local directory.
Then I created another Gradle project to use this .jar file, the critical dependency here being
compile files('D:/My Documents/software projects/misc/localJars/XGradleLibExp.jar' )
The file to use this class looks like this:
package core
import XGradleLibExp.IndexManager
class Test {
public static void main( args ) {
println "hello xxx"
Printer printer = new Printer()
IndexManager im = new IndexManager( printer )
def result = im.makeIndexFromDbaseTable()
println "call result $result"
}
}
class Printer {
def outPS = new PrintStream(System.out, true, 'UTF-8' )
}
... I had designed IndexManager to use an auxiliary class, which had a property outPS. Groovy duck-typing means you just have to supply anything with such a property and hopefully things work.
The above arrangement didn't run: although you can do build and installdist without errors, the attempt to execute the distributed executable fails because the above 6 compile dependency lines are not present in build.gradle of the "consumer" project. When you put them in this "consumer" Gradle project's build.gradle, it works.
No doubt you can add the version to the generated .jar file, and thus keep older versions for use with "consumer" projects. What I don't understand is how you might harness the mechanism which makes the downloading and use of the dependencies needed by the .jar as automatic as we are used to for things obtained from "real repositories".
PS in the course of my struggles today I seem to have found that Gradle's "maven-publish" plugin is not compatible with Gradle 5.+ (which I'm using). This may or may not be relevant: some people have talked of using a "local Maven repository". I have no idea whether this is the answer to my problem... Await input from an über-Gradle-geek... :)

You should be able to update the Eclipse model to reflect this project-to-project dependency. It looks something like this (in ProjectB's build.gradle):
apply plugin: 'eclipse'
eclipse {
classpath.file.whenMerged {
entries << new org.gradle.plugins.ide.eclipse.model.ProjectDependency('/ProjectA')
}
project.file.whenMerged {
// add a project reference, which should show up in /ProjectB/.project's <projects> element
}
}
These changes may be to the running data model, so they may not actually alter the .classpath and .project files. More info can be found here: https://docs.gradle.org/current/dsl/org.gradle.plugins.ide.eclipse.model.EclipseModel.html
This issue is discussed here: http://gradle.1045684.n5.nabble.com/Gradle-s-Eclipse-DSL-and-resolving-dependencies-to-workspace-projects-td4856525.html and a bug was opened but never resolved here: https://issues.gradle.org/browse/GRADLE-1014

Related

Gradle - one project, multiple packages, multiple jars

I'm asking you about a very basic question but I hope you can find the time to help me:
I'm trying to realise a java-project, that can spit out several different programs which partially have dependencies on other projects of mine.
In order to keep it simple, I want to have all the code in one project, run by Gradle, so if I make changes to a central library (the database connector for example) all the child-programs automatically recieve the changes.
An example could look like this:
project:
program_A
central_library
program_B
output:
program_A.jar (including central library)
program_B.jar (including central library)
Now I'm having serious troubles finding a correct buildscript for this and was wondering if someone here could help me out.
P.S. : Since I'm new to this, if I should realize this through different modules within the Gradleproject instead of different packages in the Gradleprojects sourcefile, feel free to tell me :)
One way to approach this is to have a root project, that holds the three other projects inside of it.
Specify the sub-projects inside its settings.gradle file:
rootProject.name = 'RootProject'
include 'program_A'
include 'central_library'
include 'program_B'
With this in place, program_a can depend on central_library by adding a dependency in its build.gradle:
dependencies {
compile project(':central_library')
}
I have a similar setup in one of my projects, although the "central library" is the root project and the submodules are test environments.
Create a root directory and put each library or program into its own sub-directory.
Create a gradle project in each subproject.
You can for example create a skeleton gradle project by running
gradle init --type=java-library
or
gradle init --type=java-application
Then in the root directory create a gradle multi-module project. Basically
run only
gradle init
and then create a settings.gradle and list all sub-projects there.
This is actually described very well in the gradle documentation:
https://guides.gradle.org/creating-multi-project-builds/
If I understand correctly, what you want to do is, when you change your local projects, you want other projects to see those details. For this you need to publish your projects to some kind of repo, like maven repo. You can do this from command line gradle publishToMavenLocal, or gradle build pTMl. You can also do this in build.gradle file with something like the following:
task sourceJar (type : Jar) {
classifier = constants.extSources
from sourceSets.main.allSource
}
publications {
mavenJava(MavenPublication) {
from components.java
artifact(sourceJar) {
classifier "sources" //classifier = constants.extSources
}
}
}

Outsource java packages for reuse in other projects with gradle

Ive got an Project an within it,I developed a bunch of classes wich is kept very abstract so I could use it in other projects. How should I outsource the package in a way so I can include it via gradle or by the IDE in the end?
Also the reusable packag-content is still in development so I want do work on it in paralelle.
Can anybody tell me how to solve this?
In your build.gradle use a custom build to collect only the package that you want
task customBuild(type: Jar) {
from ("src/main/java/abstract/"){
into "abstract"
}
version = ""
baseName = "myClasses"
}
it will build you a jar file inside build/libs/YouJarName
Now you can copy the jar to anywhere you want, and include it in another project in that way :
dependencies {
compile fileTree (dir : "your/jar/location", includes: ["myJar.jar"])
}

Gradle multi project - sharing source code between projects

In a gradle multi project (java), it is possible to share source code so that each project has access to it and compiles against it?
For example, sub projects 'mouse', 'cat', 'dog', containing a single java class in each - Mouse.java Cat.java, and Dog.java respectively. Each of these classes extends Animal.java.
A caveat is that when any given sub-project (e.g, 'mouse') is being built, it has some compile time dependencies defined (from maven central) and it requires that Animal.java gets compiled using those some dependencies. The same goes for the other projects. So, I can't compile and jar up Animal.java and then use that jar as a dependency of the 3 projects. Animal must get recompiled together with the source of the dependent project. The result should be mouse.jar, cat.jar, and dog.jar, each in their respective project build dir (as usual) and each also containing their version of Animal.class.
I understand that the example isn't very intuitive (as Animal should be generic enough to be compiled independently). It's the best I could find to simulate the hard to explain scenario I'm trying to solve.
Is that possible to do in Gradle?
Thank you.
solved this with sourceSets. Added the parent project main source set to the sub projects:
e.g, added to build.gradle of project 'mouse':
sourceSets {
main.java.srcDir project(':animal').sourceSets.main.java
}

How do I include a local jar dependency in Gradle?

This must be fairly simple to accomplish, but I can't seem to get it right.
I have a gradle task that creates a jar from some external classes, and my code is heavily dependent on those classes. When I try to build, I get errors from compileJava saying package <com.etc...> does not exist for the import lines in my classes.
Here's the relevant code
project.ext.set("myVersion", "v1")
dependencies {
// tried this, but it gives me a circular dependency error for my compile & zip tasks
compile files('${buildDir}/dist/my-jar-${project.myVersion}.jar') {
builtBy 'zipExternalClasses'
}
// tried either of these, but still get package does not exist
compile files('${buildDir}/dist/my-jar-${project.myVersion}.jar')
runtime files('${buildDir}/dist/my-jar-${project.myVersion}.jar')
}
// The dependent task compileExternalClasses compiles the classes from a source folder
// I can see that the jar is successfully created in 'build/dist'
task zipExternalClasses(dependsOn: 'compileExternalClasses', type: Jar) {
// code for zipping compiled external classes
}
This is what i do to include local jars.
I place them in a app/libs folder.
Then in the build.gradle (Module: app) looks like this:
dependencies {
compile project(':protobuf')
compile files('libs/android-support-v13.jar')
}
Where "android-support-v13.jar" is the jar file i previously placed in libs folder.
I think the problem might be that you are using single quote in your file path. Single quoted String in Groovy does not do String interpolation so what you essentially get as your path is just ${buildDir}/dist/my-jar-${project.myVersion}.jar itself, which is clearly not right.
Just try double quotes like below:
dependencies {
compile files("${buildDir}/dist/my-jar-${project.myVersion}.jar")
}
The variables, 'buildDir' and 'project.myVersion', will be substituted with the real value when the String is evaluated.
Take a look at the Groovy documentation about String and GString and I'm sure it'll be useful.

How can I import one Gradle script into another?

I have a complex Gradle script that wraps up a load of functionality around building and deploying a number of NetBeans projects to a number of environments.
The script works very well, but in essence it is all configured through half a dozen maps holding project and environment information.
I want to abstract the tasks away into another file, so that I can simply define my maps in a simple build file, and import the tasks from the other file. In this way, I can use the same core tasks for a number of projects and configure those projects with a simple set of maps.
Can anyone tell me how I can import one Gradle file into another, in a similar manner to Ant's task? I've trawled Gradle's docs to no avail so far.
Additional Info
After Tom's response below, I thought I'd try and clarify exactly what I mean.
Basically I have a Gradle script which runs a number of subprojects. However, the subprojects are all NetBeans projects, and come with their own ant build scripts, so I have tasks in Gradle to call each of these.
My problem is that I have some configuration at the top of the file, such as:
projects = [
[name:"MySubproject1", shortname: "sub1", env:"mainEnv", cvs_module="mod1"],
[name:"MySubproject2", shortname: "sub2", env:"altEnv", cvs_module="mod2"]
]
I then generate tasks such as:
projects.each({
task "checkout_$it.shortname" << {
// Code to for example check module out from cvs using config from 'it'.
}
})
I have many of these sort of task generation snippets, and all of them are generic - they entirely depend on the config in the projects list.
So what I want is a way to put this in a separate script and import it in the following sort of way:
projects = [
[name:"MySubproject1", shortname: "sub1", env:"mainEnv", cvs_module="mod1"],
[name:"MySubproject2", shortname: "sub2", env:"altEnv", cvs_module="mod2"]
]
import("tasks.gradle") // This will import and run the script so that all tasks are generated for the projects given above.
So, in this example, tasks.gradle will have all the generic task generation code in, and will get run for the projects defined in the main build.gradle file. In this way, tasks.gradle is a file that can be used by all large projects that consist of a number of sub-projects with NetBeans ant build files.
There is a new feature in 0.9. You can use apply from: 'other.gradle' command.
Read my question about same thing at: Is there a way to split/factor out common parts of Gradle build
The answer to the question turned out to be in the Plugins system, where you can add the desired functionality in a set of plugins which can be groovy files located in the directory buildSrc/src/main/groovy. Plugins can also be bundled as a Jar though I haven't tried this.
Details here: Custom Plugins
Well, it is hard to tell what serves you best without actually seeing your build file.
I could assume that stetting up your environment as multi-project build should provide you the abstraction you are looking for.
In your project root build.gradle you define all your domain specific stuff as well as the things that apply to all your subprojects:
repositories {
add(new org.apache.ivy.plugins.resolver.FileSystemResolver()) {
name = 'destRepo'
addIvyPattern( file( project.properties['repo.dest.dir']).absolutePath + '/[organisation]/[module]/ivys/ivy(-[revision]).xml')
addArtifactPattern( file( project.properties['repo.dest.dir']).absolutePath + '/[organisation]/[module]/[type]s/[artifact](-[revision]).[ext]')
descriptor = 'optional'
checkmodified = true
}
...
}
...
subprojects {
sourceCompatibility = 1.5
targetCompatibility = 1.5
group = 'my.group'
version = '1.0'
uploadArchives {
uploadDescriptor = true
repositories {
add rootProject.repositories.destRepo
}
}
apply{ type my.group.gradle.api.plugins.MyPlugin }
...
}
dependsOnChildren()
The project root directory might also contain a gradle.properties file where you define properties used by your projects:
buildDirName=staging
repo.dest.dir=/var/repo
...
Then in an additional file from your project root named settings.gradle you actually point to your subprojects:
include 'my-first-component',
'my-second-component'
...
project(':my-first-component').projectDir = new File(rootDir, 'path/to/first/component')
project(':my-second-component').projectDir = new File(rootDir, 'path/to/second/component')
...
Each sub-project directory contains a build.gradle file containing the sub-project specific stuff only.
No matter if you invoke gradle from your project root or sub-project directory, gradle will automatically consider all your definitions done in the various files.
Also note that no compile task will be executed for your project root as long as you don't load any plugin beyond the default plugin at the root level.
This is an example for Kotlin DSL (build.gradle.kts).
apply(from = "scripts/my-script.gradle.kts")
scripts/my-script.gradle.kts:
println(
"""
I am defined at the top level of the script and
executed at the configuration phase of build process
"""
)
tasks.create("MyTask") {
println(
"""
I am defined in a task and
run at the configration phase of build process"""
)
doLast {
// ...
}
}
See this answer and this answer for how to import a function from another script in Kotlin DSL.
Based off this similar question/answer, the easiest solution I've found after searching for days is using buildscript.sourceFile. It correctly gives the file being run rather than the pwd/cwd/parent-file of said process. I feel like this would solve your issue.

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