创建可执行 Jar，其中包含所有依赖项作为打包的 jar

Question

I'm trying to understand how to include all of the dependencies in an executable jar file as packaged jars (ie include jars within a jar) but I'm failing miserably.

Could someone point me in the right direction please?

Note that I wan't the resultant fat jar to have jars packaged within it not the un-packaged equivalent that you get using the maven-assembly-plugin

Answer 1

What you want to create is called a fat jar . You can generate it by doing next steps.

Add Build section in your POM file as follows:

<build>
    <finalName>example</finalName>
    <plugins>

        <!-- Set a compiler level -->
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>2.3.2</version>
            <configuration>
                <source>${jdk.version}</source>
                <target>${jdk.version}</target>
            </configuration>
        </plugin>

        <!-- Maven Assembly Plugin -->
        <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>
                <!-- MainClass in mainfest make a executable jar -->
                <archive>
                  <manifest>
                    <mainClass>com.example.Main</mainClass>
                  </manifest>
                </archive>

            </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>

Above “Maven Assembly Plugin” is bind to the Maven’s packaging phase , to produces the final Jar, just package it using:

mvn package

Two jar files will be created in the target folder.

• example.jar – Only your project classes

• example-jar-with-dependencies.jar – Project and dependency classes in a single jar.

You can now check the contents of your fat jar with:

jar tf target/example-jar-with-dependencies.jar 

Answer 2

Include dependencies in the pom.xml. Build the project using mvn clean install and the result will have these dependencies. You can then run the jar using

java -cp <jar Filename> <main class name>