How To Exclude File from a Jar file.

Gradle task Jar has a property excludes which takes an array as an input and exclude these files from the Jar file it creates.

Let's assume the following directory structure

Following example excludes files from the Jar file.

task createExcludingFiles(type :Jar){
    from ('src'){
        excludes = ["main/java/com/ekiras/demo/D.java","main/java/com/ekiras/demo/E.java"]
    }
}

This will exclude files D.java, E.java from the jar file. Run the gradle task using command gradle -q createExcludingFiles. The Jar file created will have the following files.

META-INF/
META-INF/MANIFEST.MF
main/
main/java/
main/java/com/
main/java/com/ekiras/
main/java/com/ekiras/demo/
main/java/com/ekiras/demo/A.java
main/java/com/ekiras/demo/C.java
main/java/com/ekiras/demo/F.java
main/java/com/ekiras/demo/B.java
main/java/com/ekiras/demo/p1/
main/java/com/ekiras/demo/p1/X.java
main/java/com/ekiras/demo/p1/Z.java
main/java/com/ekiras/demo/p1/Y.java
test/
test/java/
main/resources/
test/resources/

Exclude Package in Jar file

task createExcludingPackage(type :Jar){
    from ('src'){
        excludes = ["main/java/com/ekiras/demo/D.java" ,"main/java/com/ekiras/demo/p1/**"]
    }
}

Run the task using command gradle -q createExcludingPackage. This will remove

1. All the files from package p1
2. Class D.java

The Jar file created will have the following files.

META-INF/
META-INF/MANIFEST.MF
main/
main/java/
main/java/com/
main/java/com/ekiras/
main/java/com/ekiras/demo/
main/java/com/ekiras/demo/A.java
main/java/com/ekiras/demo/E.java
main/java/com/ekiras/demo/C.java
main/java/com/ekiras/demo/F.java
main/java/com/ekiras/demo/B.java
test/
test/java/
main/resources/
test/resources/

How to name a Jar file

Lets take the following jar file for explaning the jar naming conventions.

customName_wrapper_2.0.1_SNAPSHOT.jar

A jar file has the following properties

Here property archiveName if specified will override all the other naming conventions like baseName etc. It should be a fully qualified name of the Jar including the extension (.jar)

Other Properties of Gradle Task :: Jar

Creating a Jar file

Let's assume the following directory structure

Create a Jar file with all files.

We can write a gradle task to include all files in src to our jar file as follows

task createAll(type : Jar){
    from 'src'
}

When we run the gradle task as gradle -q createAll will give the following files in the jar

META-INF/
META-INF/MANIFEST.MF
main/
main/java/
main/java/com/
main/java/com/ekiras/
main/java/com/ekiras/demo/
main/java/com/ekiras/demo/D.java
main/java/com/ekiras/demo/A.java
main/java/com/ekiras/demo/E.java
main/java/com/ekiras/demo/C.java
main/java/com/ekiras/demo/F.java
main/java/com/ekiras/demo/B.java
main/java/com/ekiras/demo/p1/
main/java/com/ekiras/demo/p1/X.java
main/java/com/ekiras/demo/p1/Z.java
main/java/com/ekiras/demo/p1/Y.java
test/
test/java/
main/resources/
test/resources/

Create a Jar file from a Package.

task createFromPackage(type : Jar){
    from ("src/main/java/com/ekiras/demo/p1")
}

Run the above task with command gradle -q createFromPackage, it will give the following files in jar.

META-INF/
META-INF/MANIFEST.MF
X.java
Z.java
Y.java

Create a Jar file with Selected Files.

task createSelectedJar(type : Jar){
    from ('src/main/java/com/ekiras/demo'){
        includes = ["A.java","B.java", "p1/X.java", "p1/Y.java"]
    }
}

Run the above command with command gradle -q createSelectedJar

META-INF/
META-INF/MANIFEST.MF
A.java
B.java
p1/
p1/X.java
p1/Y.java

Create a Jar file excluding some files

task createExcludingFiles(type :Jar){
    from ('src'){
        excludes = ["main/java/com/ekiras/demo/D.java","main/java/com/ekiras/demo/E.java", "main/java/com/ekiras/demo/p1/**"]
    }
}

Run the gradle task with command gradle -q createExcludingFiles. It will result in a jar file with the following files

META-INF/
META-INF/MANIFEST.MF
main/
main/java/
main/java/com/
main/java/com/ekiras/
main/java/com/ekiras/demo/
main/java/com/ekiras/demo/A.java
main/java/com/ekiras/demo/C.java
main/java/com/ekiras/demo/F.java
main/java/com/ekiras/demo/B.java
test/
test/java/
main/resources/
test/resources/

To Sum up all the exmaples above

Following is a gradle task that create a jar file

task createJar(type: Jar){
    from ('src/main/java/com/ekiras/demo'){
        includes = ["A.java","B.java", "p1/**"]
        excludes = ["D.java","E.java"]
    }
    baseName = 'customName'
    appendix = 'wrapper'
    version = "2.0.1"
    classifier = 'SNAPSHOT'
    archiveName = "${baseName}_${appendix}_${version}_${classifier}.jar"
    extension  = "ext"
    destinationDir = new File("${buildDir}/test/a")

    manifest {
        attributes = [
                'Main-Class' : "com.ekiras.A",
                'Version'    : 2.0
         ]
    }
}

we can also write a gradle task to see the files that were created inside the jar file as follows

task showFiles(dependsOn : createJar){
    doLast{
        FileTree files = zipTree("${buildDir}/test/a/${archiveName}")
        files.each {
            println "${it.name}"
        }
    }
}

When we run the task gradle -q createJar showFiles or simply gradle -q showFiles , it will give the following result

A.java
B.java
MANIFEST.MF
X.java
Y.java
Z.java

How to create a jar file.

We can make a jar file with a single class using the following commands

Here can be replaced by the name of the jar file you want.

1. Create a jar file with single file

jar --create --file=<FileName> <file-1>

2. Create a jar file with multiple files

jar --create --file=<FileName> <file-1> <file-2>

3. Create a jar file with all files in a directory

jar --create --file="<FileName> -C /path/to/dir/ ."

Here -C specifies the directory and . specifies that it need to include all the files in te directory.

Some of the shorthands for the above commands

How to extract a jar file

jar -xf <FileName>

How to list the contents of a jar file

jar -tf <FileName>