How do you create a standalone application with dependencies intact using Maven?

Question

I have a desktop Java application built using Maven 2 (but I could upgrade to Maven 3 if that helps) with a number of open source dependencies. I'm now trying to package it up as a standalone to make it available to end users without them needing to install maven or anything else.

I've successfully used maven-assembly-plugin to build a single jar containing all dependencies but this is not really what I want because when using LGPL libraries you are meant to redistribute the libraries you are using as separate jars.

I want Maven to build a zip containing a jar with my code and a MANIFEST.MF that refers to the other jars I need together with the other jars. This seems like standard practice but I cannot see how to do it.

Here's an extract from my pom

     <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <encoding>UTF-8</encoding>
                    <compilerVersion>1.6</compilerVersion>
                    <source>1.6</source>
                    <target>1.6</target>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-surefire-plugin</artifactId>
                <configuration>
                    <argLine>-Dfile.encoding=UTF-8</argLine>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <version>2.4</version>
                <configuration>
                    <archive>
                        <manifest>
                            <mainClass>com.company.widget.Main</mainClass>
                            <packageName>com.company.widget</packageName>
                            <addClasspath>true</addClasspath>
                        </manifest>
                    </archive>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-assembly-plugin</artifactId>
                <version>2.3</version>
                <configuration>
                    <descriptorRefs>
                        <descriptorRef>jar-with-dependencies</descriptorRef>
                    </descriptorRefs>
                    <archive>
                        <manifest>
                            <mainClass>com.company.widget.Main</mainClass>
                            <packageName>com.company.widget</packageName>
                            <addClasspath>true</addClasspath>
                        </manifest>
                    </archive>
                </configuration>
                <executions>
                    <execution>
                        <id>make-assembly</id>
                        <phase>package</phase>
                        <goals>
                            <goal>single</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build> 

EDIT:Taken on Kals idea

created a file called descriptor.xml

<?xml version="1.0" encoding="UTF-8"?>
<assembly
    xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.0 http://maven.apache.org/xsd/assembly-1.1.0.xsd">
    <id>distribution</id>
    <formats>
        <format>zip</format>
    </formats>
    <dependencySets>
        <dependencySet>
            <scope>runtime</scope>
            <outputDirectory>lib</outputDirectory>
            <unpack>false</unpack>
        </dependencySet>
    </dependencySets>
</assembly>

and pom contains:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-assembly-plugin</artifactId>
    <version>2.3</version>
    <configuration>
        <descriptors>
            <descriptor>assembly.xml</descriptor>
        </descriptors>
        <archive>
            <manifest>
                <mainClass>com.company.widget.cmdline.Main</mainClass>
                <packageName>com.company.widget</packageName>
                <addClasspath>true</addClasspath>
            </manifest>
        </archive>
    </configuration>
    <executions>
        <execution>
            <id>make-assembly</id>
            <phase>package</phase>
            <goals>
                <goal>single</goal>
            </goals>
        </execution>
    </executions>
</plugin>

Now maintains the jar and puts them all in the lib folder, including my own code

Answer 1

Try creating a custom assembly descriptor and add a dependencySet and make sure you specify, unpack as false.

Use this as assembly descriptor,

<?xml version="1.0" encoding="UTF-8"?>
<assembly
    xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.0 http://maven.apache.org/xsd/assembly-1.1.0.xsd">
    <id>distribution</id>
    <formats>
        <format>zip</format>
    </formats>
    <dependencySets>
        <dependencySet>
            <scope>runtime</scope>
            <outputDirectory>lib</outputDirectory>
                        <useProjectArtifact>false</useProjectArtifact>
            <unpack>false</unpack>
        </dependencySet>
    </dependencySets>
</assembly>

Store this file to say src/main/assembly/assembly.xml and update your assembly plugin configuration in pom.xml like this.

        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-assembly-plugin</artifactId>
            <version>2.2.1</version>
            <executions>
                <execution>
                    <id>assembly</id>
                    <phase>package</phase>
                    <goals>
                        <goal>attached</goal>
                    </goals>
                    <configuration>
                           <descriptor>${basedir}/src/main/assembly/assembly.xml</descriptor>
                    </configuration>
                </execution>
            </executions>
        </plugin>

Here is assembly descriptor reference if you need anything more

http://maven.apache.org/plugins/maven-assembly-plugin/assembly.html

Answer 2

You should check out the Maven Appassembler plugin. You can get a lot more robust package using it than rolling your own assembly.

It generates helpful startup scripts for Unix and Windows that allow you to set predefined JAVA VM options, commandline parameters and classpath.

It also has a concept of configuration directory where you can copy default configurations that user can later change. You can also set the configuration directory to be available on the classpath.

Dependencies can be saved in a Maven style "repo" or you can use a flat style "lib" directory.

You still need the assembly plugin for creating a zip or tar archive.

Here's an example appassembler configuration:

<plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>appassembler-maven-plugin</artifactId>
    <version>1.2.2</version>
    <configuration>
        <programs>
            <program>
                <mainClass>com.mytools.ReportTool</mainClass>
                <name>ReportTool</name>
            </program>
        </programs>
        <assembleDirectory>${project.build.directory}/ReportTool</assembleDirectory>
        <repositoryName>lib</repositoryName>
        <repositoryLayout>flat</repositoryLayout>
    </configuration>
    <executions>
        <execution>
            <id>assembly</id>
            <phase>package</phase>
            <goals>
                <goal>assemble</goal>
            </goals>
        </execution>
    </executions>
</plugin>

To get a zip archive I use the this assembly:

<assembly xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.0"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.0 http://maven.apache.org/xsd/assembly-1.1.0.xsd">
    <id>bin</id>
    <formats>
        <format>zip</format>
    </formats>
    <fileSets>
        <fileSet>
            <directory>${project.build.directory}/ReportTool</directory>
            <outputDirectory>/</outputDirectory>
            <includes>
                <include>/**</include>
            </includes>
        </fileSet>
    </fileSets>
</assembly>

Answer 3

As far as I know it is possible to redistribute also LGPL libraries into your own packages as long as they are untouched. The maven assembly plugin creates a jar that contains the original jars inside a lib folder of the archive. So far you are fulfilling the LGPL.

Maybe this question gives some more information about this topic.

(Disclaimer: I'm not a lawyer, so please crosscheck this information ;) )

Answer 4

Add the following plugins in pom.xml. Check the value at mainClass,classpathPrefix,addClasspath tags.

<plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-jar-plugin</artifactId>
            <version>2.4</version>
            <configuration>
                <archive>
                    <manifest>
                        <mainClass>org.apache.camel.spring.Main</mainClass>
                        <classpathPrefix>lib/</classpathPrefix>
                        <addClasspath>true</addClasspath>
                    </manifest>
                </archive>
            </configuration>
        </plugin>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-assembly-plugin</artifactId>
            <version>2.4</version>
            <configuration>
                <descriptors>
                    <descriptor>src/assembly/some-assembly.xml</descriptor>
                </descriptors>
            </configuration>
            <executions>
                <execution>
                    <id>make-assembly</id>
                    <phase>package</phase>
                    <goals>
                        <goal>single</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>

Create some-assembly.xml under src/assembly as below.

<assembly
xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.0 http://maven.apache.org/xsd/assembly-1.1.0.xsd">
<id>distribution</id>
<formats>
    <format>zip</format>
</formats>
<includeBaseDirectory>true</includeBaseDirectory>
<fileSets>
    <fileSet>
        <directory>${project.build.directory}</directory>
        <outputDirectory>/</outputDirectory>
        <includes>
            <include>*.jar</include>
        </includes>
    </fileSet>
</fileSets>
<dependencySets>
    <dependencySet>
        <scope>runtime</scope>
        <outputDirectory>/lib</outputDirectory>
        <useProjectArtifact>false</useProjectArtifact>
        <unpack>false</unpack>
    </dependencySet>
</dependencySets>

Note that useProjectArtifact flag to false, unpack flag to false. If root folder inside zip file is not required,then one can make includeBaseDirectory to false.

This will create name-version-distribution.zip file. Inside zip file, there will be folder name-version. Inside this folder, your executable jar and lib folder containing all dependency jars will be present. Check manifest.MF file of executable jar. It contains both main class and classpath information.