Generate complete package (ZIP) of Java (executable jar) application with required dependencies in it using Maven

 Posted on May 17, 2013  |  4 minutes  |  753 words  |  Pandurang Patil

To generate a zip file, packaging all required dependent libraries and newly generated jar, using maven-assembly-plugin (for more detail on plugin refer).

I will demonstrate generation of package using assembly descriptor file.

  1. Create a assembly descriptor file which is a xml file (for more details refer and format) as following. Create this file inside your project directory. One can keep this descriptor file any where inside given project directory. I have tried it by keeping this file at location <Project dir>/src/main/assembly/test-app-assembly.xml andproviding complete path to descriptor file in pom.xml.

e.g

test-app-assembly.xml

<?xml version="1.0" encoding="UTF-8"?>  
<assembly xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.2 http://maven.apache.org/xsd/assembly-1.1.2.xsd">  
    <formats>  
        <format>zip</format>  
    </formats>  
    <files>  
        <file>  
            <outputDirectory>/</outputDirectory>  
            <source>target/test-app.jar</source>  
        </file>  
    </files>  
    <!-- use this section if you want to package dependencies -->  
    <dependencySets>  
        <dependencySet>  
            <outputDirectory>lib</outputDirectory>  
            <useStrictFiltering>true</useStrictFiltering>  
            <useProjectArtifact>false</useProjectArtifact>  
            <scope>runtime</scope>  
        </dependencySet>  
    </dependencySets>  
</assembly>
  1. In above descriptor file, its assumed the current project artifact is generated before this plugin gets executed and maven-assembly-plugin configured to run in install phase only.
  2. refer lines inside <files>....</files> in above code. We are specifying include generated artifact from the current module inside packaging, which will be placed inside root / directory of the package zip. Note: by default maven generates artifact in following format <artifact name>-<version>.jar (with assumption packaging mentioned as jar). You need to make sure to specify constant file name using property <finalName> inside your pom.xml

e.g

Section of pom.xml

<build>  
    ......  
    ....  
        <finalName>test-app.jar</finalName>   
    .......  
    ....  
</build>
  1. Next refer lines inside <dependencySets> .... </dependencySets>. Here we are specifying copy all dependency jars inside /lib directory of the package zip.
  2. Next refer below changes in pom.xml.

e.g.

Section of pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">  
    ......  
    .........  
    <build>  
        <finalName>test-app</finalName>  
        <plugins>  
            <plugin>  
                <groupId>org.apache.maven.plugins</groupId>  
                <artifactId>maven-assembly-plugin</artifactId>  
                <executions>  
                    <execution>  
                        <id>create-distribution</id>  
                        <phase>install</phase>  
                        <goals>  
                            <goal>single</goal>  
                        </goals>  
                        <configuration>  
                            <descriptors>  
                                <descriptor>src/main/assembly/test-app-assembly.xml</descriptor>  
                            </descriptors>  
                        </configuration>  
                    </execution>  
                </executions>  
            </plugin>  
            ................  
            ................  
        </plugins>  
    </build>  
</project>
  1. Refer line 8 - 25 in above code from sample pom.xml. Here we are configuring maven-assembly-plugin to invoke single goal in install phase by referring test-app-assembly.xml file (refer line 20).
  2. When you run the build mvn clean install at the end you will see file test-app.zip is generated inside target folder. If you open the zip file you will find test-app.jar and lib folder in it and if you go inside lib folder you will find all required dependencies of current project are copied inside this lib folder.

Above steps demonstrates how to generate required single package as zip with all required dependencies in it. Now we will look at how to make given application as executable jar (When I say executable jar, one can configure main class of given application, so that JVM can invoke the application directly without specifying which class to invoke on command line. you can run application like <extracted location of zip>$ java -jar test-app.jar -classpath <location of each dependent jar file>). But its not just sufficient to just specify only main class, we also need to add required dependent jar files in class path while running application from command prompt. If we can add those dependent jar locations inside jar itself then you don’t have to mention it at command line. Refer below code changes using maven-jar-plugin.

Section of pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">  
    ......  
    .........  
    <build>  
        <finalName>test-app</finalName>  
        <plugins>  
            <plugin>  
                <groupId>org.apache.maven.plugins</groupId>  
                <artifactId>maven-assembly-plugin</artifactId>  
                <executions>  
                    <execution>  
                        <id>create-distribution</id>  
                        <phase>install</phase>  
                        <goals>  
                            <goal>single</goal>  
                        </goals>  
                        <configuration>  
                            <descriptors>  
                                <descriptor>src/main/assembly/test-app-assembly.xml</descriptor>  
                            </descriptors>  
                        </configuration>  
                    </execution>  
                </executions>  
            </plugin>  
            <plugin>  
                <groupId>org.apache.maven.plugins</groupId>  
                <artifactId>maven-jar-plugin</artifactId>  
                <configuration>  
                    <archive>  
                        <manifest>  
                            <addClasspath>true</addClasspath>  
                            <classpathPrefix>lib/</classpathPrefix>  
                            <mainClass>com.pp.test.Sample</mainClass>  
                        </manifest>  
                    </archive>  
                </configuration>  
            </plugin>  
        </plugins>  
    </build>  
</project>
  1. refer line having tag <mainClass>, here we are specifying which class having main method. At line having tag <addClasspath> we are specifying add all dependency jars into classpath. But as all the dependent jars we have placed inside lib folder as per above packaging configuration written in test-app-assembly.xml, while specifying class path we need to prefix jar file name with lib/ refer tag <classpathPrefix>. This will result in generation of META-INF/MANIFEST.MF file refer sample below.

Sample META-INF/MANIFEST.MF

 Manifest-Version: 1.0  
 Archiver-Version: Plexus Archiver  
 Created-By: Apache Maven  
 Built-By: pandurang  
 Build-Jdk: 1.7.0_17  
 Main-Class: com.pp.test.Sample  
 Class-Path: lib/javapns-2.2.jar lib/junit-4.8.1.jar lib/commons-lang-2.6.jar lib/commons-io-2.4.jar lib/mail-1.4.5.jar lib/activation-1.1.jar lib/google-http-client-jackson2-1.13.1-beta.jar lib/j  
  ackson-core-2.0.5.jar lib/jcommander-1.30.jar lib/log4j-1.2.17.jar lib/slf4j-api-1.6.6.jar
  1. With this you will be able to generate complete zip file with an executable jar file in it. Which makes the deployment and execution of application very easy. For deployment you need to just ship this generated test-app.zip file which is a complete package. To run your application you can extract the zip file and issue following command <extracted location of zip>$ java -jar test-app.jar</span>. Note here when jar is generated all required dependencies are mentioned inside MANIFEST.MF you don’t have to specify them here.
java  assembly  executableJar 

See also