How can I create an executable JAR with dependencies using Maven?

soemirno_67219 0
Viewed 1730563

I want to package my project in a single executable JAR for distribution.

How can I make a Maven project package all dependency JARs into my output JAR?

executable-jar build-automation build-process maven-2 java
33 Answers
<build>
  <plugins>
    <plugin>
      <artifactId>maven-assembly-plugin</artifactId>
      <configuration>
        <archive>
          <manifest>
            <mainClass>fully.qualified.MainClass</mainClass>
          </manifest>
        </archive>
        <descriptorRefs>
          <descriptorRef>jar-with-dependencies</descriptorRef>
        </descriptorRefs>
      </configuration>
    </plugin>
  </plugins>
</build>

and you run it with

mvn clean compile assembly:single

Compile goal should be added before assembly:single or otherwise the code on your own project is not included.

See more details in comments.

Commonly this goal is tied to a build phase to execute automatically. This ensures the JAR is built when executing mvn install or performing a deployment/release.

<build>
  <plugins>
    <plugin>
      <artifactId>maven-assembly-plugin</artifactId>
      <configuration>
        <archive>
          <manifest>
            <mainClass>fully.qualified.MainClass</mainClass>
          </manifest>
        </archive>
        <descriptorRefs>
          <descriptorRef>jar-with-dependencies</descriptorRef>
        </descriptorRefs>
      </configuration>
      <executions>
        <execution>
          <id>make-assembly</id> <!-- this is used for inheritance merges -->
          <phase>package</phase> <!-- bind to the packaging phase -->
          <goals>
            <goal>single</goal>
          </goals>
        </execution>
      </executions>
    </plugin>
  </plugins>
</build>
mark_304530

Taking IAdapter's answer and reformatting it, we have:

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-jar-plugin</artifactId>
            <configuration>
                <archive>
                    <manifest>
                        <addClasspath>true</addClasspath>
                        <mainClass>fully.qualified.MainClass</mainClass>
                    </manifest>
                </archive>
            </configuration>
        </plugin>
        <plugin>
            <artifactId>maven-assembly-plugin</artifactId>
            <configuration>
                <descriptorRefs>
                    <descriptorRef>jar-with-dependencies</descriptorRef>
                </descriptorRefs>
            </configuration>
        </plugin>
    </plugins>
</build>

Next, I would recommend making this a natural part of your build, rather than something to call explicitly. To make this a integral part of your build, add this plugin to your pom.xml and bind it to the package lifecycle event. However, a gotcha is that you need to call the assembly:single goal if putting this in your pom.xml, while you would call 'assembly:assembly' if executing it manually from the command line.

<project>
  [...]
  <build>
      <plugins>
          <plugin>
              <artifactId>maven-assembly-plugin</artifactId>
              <configuration>
                  <archive>
                      <manifest>
                          <addClasspath>true</addClasspath>
                          <mainClass>fully.qualified.MainClass</mainClass>
                      </manifest>
                  </archive>
                  <descriptorRefs>
                      <descriptorRef>jar-with-dependencies</descriptorRef>
                  </descriptorRefs>
              </configuration>
              <executions>
                  <execution>
                      <id>make-my-jar-with-dependencies</id>
                      <phase>package</phase>
                      <goals>
                          <goal>single</goal>
                      </goals>
                  </execution>
              </executions>
          </plugin>
      [...]
      </plugins>
    [...]
  </build>
</project>
Matthew_McCullough_560390

You can use the maven-shade plugin to build an über JAR file like below:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-shade-plugin</artifactId>
    <executions>
        <execution>
            <phase>package</phase>
            <goals>
                <goal>shade</goal>
            </goals>
        </execution>
    </executions>
</plugin>
user_30888970

I have long used the Maven assembly plugin, but I could not find a solution to the problem with "already added, skipping". Now, I'm using another plugin - onejar-maven-plugin. An example is below (mvn package builds the JAR file):

<plugin>
    <groupId>org.dstovall</groupId>
    <artifactId>onejar-maven-plugin</artifactId>
    <version>1.3.0</version>
    <executions>
        <execution>
            <configuration>
                <mainClass>com.company.MainClass</mainClass>
            </configuration>
            <goals>
                <goal>one-jar</goal>
            </goals>
        </execution>
    </executions>
</plugin>

You need to add a repository for that plugin:

<pluginRepositories>
    <pluginRepository>
        <id>onejar-maven-plugin.googlecode.com</id>
        <url>http://onejar-maven-plugin.googlecode.com/svn/mavenrepo</url>
    </pluginRepository>
</pluginRepositories>
user_4043950

Another option if you really want to repackage the other JARs contents inside your single resultant JAR is the Maven Assembly plugin. It unpacks and then repacks everything into a directory via <unpack>true</unpack>. Then you'd have a second pass that built it into one massive JAR.

Another option is the OneJar plugin. This performs the above repackaging actions all in one step.

Matthew_McCullough_560390

It will work like:

<plugin>
    <artifactId>maven-dependency-plugin</artifactId>
    <executions>
        <execution>
            <id>unpack-dependencies</id>
            <phase>generate-resources</phase>
            <goals>
                <goal>unpack-dependencies</goal>
            </goals>
        </execution>
    </executions>
</plugin>

Unpacking has to be in the generate-resources phase or it will not be included as resources.

user_2872440

It may not be a good idea to embed all the dependencies in the project's JAR file itself.

I see the point (ease of deployment / usage), but it depends of the use case of your project (and there may be alternatives (see below)).

If you use it fully standalone, why not?

But if you use your project in other contexts (like in a web application, or dropped in a folder where other JARs are sitting), you may have JAR duplicates in your classpath (the ones in the folder, the one in the JAR files). Maybe not a bid deal, but I usually avoid this.

A good alternative:

  • deploy your application as a ZIP or WAR file: the archive contains your project's JAR file and all dependent JAR files;
  • use a dynamic classloader mechanism (see Spring Framework, or you can easily do this yourself) to have a single entry point of your project (a single class to start - see the Manifest mechanism in another answer), which will add (dynamically) to the current classpath all the other needed JAR files.

Like this, with in the end just a manifest and a "special dynamic classloader main", you can start your project with:

java -jar ProjectMainJar.jar com.stackoverflow.projectName.MainDynamicClassLoaderClass
user_1954630

There are millions of answers already. I wanted to add you don't need <mainClass> if you don't need to add entryPoint to your application. For example, APIs may not have necessarily have a main method.

Maven plugin configuration

  <build>
    <finalName>log-enrichment</finalName>
    <plugins>
      <plugin>
        <artifactId>maven-assembly-plugin</artifactId>
        <configuration>
          <descriptorRefs>
            <descriptorRef>jar-with-dependencies</descriptorRef>
          </descriptorRefs>
        </configuration>
      </plugin>
    </plugins>
  </build>

Build

mvn clean compile assembly:single

Verify

ll target/
total 35100
drwxrwx--- 1 root vboxsf     4096 Sep 29 16:25 ./
drwxrwx--- 1 root vboxsf     4096 Sep 29 16:25 ../
drwxrwx--- 1 root vboxsf        0 Sep 29 16:08 archive-tmp/
drwxrwx--- 1 root vboxsf        0 Sep 29 16:25 classes/
drwxrwx--- 1 root vboxsf        0 Sep 29 16:25 generated-sources/
drwxrwx--- 1 root vboxsf        0 Sep 29 16:25 generated-test-sources/
-rwxrwx--- 1 root vboxsf 35929841 Sep 29 16:10 log-enrichment-jar-with-dependencies.jar*
drwxrwx--- 1 root vboxsf        0 Sep 29 16:08 maven-status/
user_4329030

I wanted to migrate my Spring application (using Apereo Foundation's CAS client) to Spring Boot 1.5. I ran into many problems, like:

no main manifest attribute, in target/cas-client-web.jar

I tried to make one unique JAR file with all dependencies. After searching on the Internet, I was able to do it with these lines:

<plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-maven-plugin</artifactId>
    <configuration>
        <fork>true</fork>
        <mainClass>${start-class}</mainClass>
    </configuration>
    <executions>
        <execution>
            <goals>
                <goal>repackage</goal>
            </goals>
        </execution>
    </executions>
</plugin>

<plugin>
    <artifactId>maven-assembly-plugin</artifactId>
    <executions>
        <execution>
            <phase>package</phase>
            <goals>
                <goal>single</goal>
            </goals>
        </execution>
    </executions>
    <configuration>
        <archive>
            <manifest>
                <addClasspath>true</addClasspath>
                <mainClass>${start-class}</mainClass>
            </manifest>
        </archive>
        <descriptorRefs>
            <descriptorRef>jar-with-dependencies</descriptorRef>
        </descriptorRefs>
    </configuration>
</plugin>

start-class is my main class:

<properties>
    <java.version>1.8</java.version>
    <start-class>com.test.Application</start-class>
</properties>

And my Application is:

package com.test;

import java.util.Arrays;

import com.test.TestProperties;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.Bean;

@SpringBootApplication
@EnableAutoConfiguration
@EnableConfigurationProperties({TestProperties.class})
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }

    @Bean
    public CommandLineRunner commandLineRunner(ApplicationContext ctx) {
        return args -> {

            System.out.println("Let's inspect the beans provided by Spring Boot:");

            String[] beanNames = ctx.getBeanDefinitionNames();
            Arrays.sort(beanNames);
            for (String beanName : beanNames) {
                System.out.println(beanName);
            }
        };
    }

}
user_57542380

I tried multiple solutions, but this is the one that worked perfectly in the scenario where we wanted to create a non-executable fat JAR file with all internal dependencies for external systems having no previous relevance. A production scenario was tested.

Include this in the pom.xml file:

<?xml version="1.0" encoding="UTF-8"?>
<build>
   <sourceDirectory>src</sourceDirectory>
   <plugins>
      <plugin>
         <artifactId>maven-compiler-plugin</artifactId>
         <version>3.8.1</version>
         <configuration>
            <source>1.8</source>
            <target>1.8</target>
         </configuration>
      </plugin>
      <plugin>
         <artifactId>maven-assembly-plugin</artifactId>
         <configuration>
            <descriptorRefs>
               <descriptorRef>jar-with-dependencies</descriptorRef>
            </descriptorRefs>
         </configuration>
      </plugin>
   </plugins>
</build>

The command to run to build the fat JAR file:

mvn assembly:assembly
user_54101500

Use:

mvn clean install -U dependency:copy-dependencies

The .jar file will be generated in the folder called "target", in the same root as the "src" folder.

user_69098320 
<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-assembly-plugin</artifactId>
            <version>2.4.1</version>
            <configuration>
                <!-- get all project dependencies -->
                <descriptorRefs>
                    <descriptorRef>jar-with-dependencies</descriptorRef>
                </descriptorRefs>
            </configuration>
            <executions>
                <execution>
                    <id>make-assembly</id>
                    <!-- bind to the packaging phase -->
                    <phase>package</phase>
                    <goals>
                        <goal>single</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>
user_103442610
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