How to create a non-executable JAR file that includes all Maven dependencies

Question

I have a Java project that doesn't have a main file but it has a lot of Maven dependencies.

How I can create a JAR-file that contains my source-code and required maven dependencies?

My 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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>NetworkCommunicationAPI</groupId>
    <artifactId>NetworkCommunicationAPI</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <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>
    <dependencies>
        <dependency>
      <groupId>org.json</groupId>
            <artifactId>json</artifactId>
            <version>20210307</version>
        </dependency>
    </dependencies>
</project>

@dan1st how I can use these plugins because for me these don't work — OffRange, Apr 25 '21 at 12:02
Can you explain why you want to create such a JAR? This is usually not done. — J Fabian Meier, Apr 25 '21 at 13:54
@JFabianMeier I wrote an API that used org.json. I added this dependency via maven. Now I want use my API in other projects so if I basicly export the API the JAR contains only my sourcecode and not the maven dependencies. To use them I would need to add the maven dependencies in each project I used my API. But I want have the maven dependencies in the JAR with my API sourcecode together so I don't need to add the maven dependencies again. — OffRange, Apr 25 '21 at 14:02
You never need to add the Maven dependencies again. Maven finds them automatically. This is the transitive dependency resolution feature of Maven. There is no need to package dependencies inside your project. — J Fabian Meier, Apr 25 '21 at 14:06
@JFabianMeier so if I basicly export my API and add the JAR to my projects as a library the maven dependencies would automatically added? But this don't worked for me — OffRange, Apr 25 '21 at 14:09
@JFabianMeier Do you mean when I export my API in my case in eclipse and add it to the `build path` in my other project that the other project will automatically load the maven dependencies I used in my API? Do I need convert the other project to an maven project? — OffRange, Apr 25 '21 at 14:28
Both projects need to be Maven projects. You need to build the projects with `mvn clean install`. — J Fabian Meier, Apr 25 '21 at 14:49

dan1st · Accepted Answer · 2021-04-25T12:18:03.483

1

You can use the maven-assembly-plugin just as you could use it for creating an executable JAR with dependencies.

The only thing you need to change is that you don't need to specify a main class:

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

After that, you can create the JAR using mvn compile assembly:single.

This compiles your sources and creates a JAR containing the compiled sources and all dependencies in the compile-scope.

edited Apr 25 '21 at 12:18

answered Apr 25 '21 at 12:06

dan1st

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I tried it but it looks like it dont work for me. I only get an JAR contains the maven dependencies – OffRange Apr 25 '21 at 12:15
You may need to run `mvn compile assembly:single` in order to run the compilation before packaging. – dan1st Apr 25 '21 at 12:17
Are your sources located in `src/main/java`? Can you show your `pom.xml`? – dan1st Apr 25 '21 at 12:27
Yes I can, I have edited the question and added the pom.xml. And no my sources are located in `src/` – OffRange Apr 25 '21 at 12:42
@OffRange Just to make sure: It is not the sources that copied to the resulting JAR, but the compiled sources, i.e. the class files. – J Fabian Meier Apr 25 '21 at 12:54
@JFabianMeier no when I create the jar via `mvn` only the maven dependencies I added in `pom.xml` and not the actual source code I wrote is copied to the JAR. – OffRange Apr 25 '21 at 13:44
Yes, this is why you need the compile step. Do the class files exist in target/classes? – dan1st Apr 25 '21 at 13:45
@dan1st yes they are – OffRange Apr 25 '21 at 13:55
And they do not end up in the final JAR? – J Fabian Meier Apr 25 '21 at 13:58
@JFabianMeier no – OffRange Apr 25 '21 at 14:05
What happens with `mvn clean compile assembly:single`? Are the classes present in `target/classes`? Does the JAR contain your classes? – dan1st Apr 25 '21 at 14:07
@dan1st no. But now the `target/classes` folder is deleted – OffRange Apr 25 '21 at 14:14
Are you sure you ran 'mvn clean **compile** assembly:single'? – dan1st Apr 25 '21 at 14:16
@dan1st I thought it already worked somehow – OffRange Apr 25 '21 at 14:23

score 0 · Answer 2 · answered Apr 25 '21 at 11:43

0

You can use the Maven shade plugin or Maven assembly plugin to create such a JAR.

In most cases, such JARs should be avoided. You create a dependency hell for everyone who uses your JAR because Maven cannot manage the included dependencies any more and therefore conflicts with other dependencies (not from your JAR) may become unmanagable.

On the other, such fat JARs are of little use because Maven or Gradle will find your transitive dependencies anyway, so there is no need to include them into the JAR.

answered Apr 25 '21 at 11:43

J Fabian Meier

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I totally agree to that opinion, but actually I found a case where a non-executable fat jar makes sense. I need to package a library jar with all dependencies to make sure it can be scanned for vulnerabilities by tools like Blackduck (binary dependency scanner). Without building a fat jar of the lib, Blackduck scans nothing. – LastZolex Jul 20 '23 at 07:43

How to create a non-executable JAR file that includes all Maven dependencies

2 Answers2