Maven：生成具有所有依赖项的可执行jar文件

Question

I recently converted one of my Java project to a Maven project. My pom.xml looks something like this:

        <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">
            <modelVersion>4.0.0</modelVersion>
            <packaging>jar</packaging>
            <groupId>com.myproject.groupid</groupId>
            <artifactId>myproject</artifactId>
            <version>0.0.1-SNAPSHOT</version>
            <name>MyProject</name>
            <description>The first version of my maven project</description>
            <dependencies>
                <dependency>
                    <groupId>com.dependent.jar</groupId>
                    <artifactId>dependentjar</artifactId>
                    <version>0.0.1</version>
                    <scope>system</scope>
                    <type>jar</type>
            <systemPath>${project.basedir}/jars/dependent.jar</systemPath>
                </dependency>   
                <dependency>
                    <groupId>org.apache.ws.commons.schema</groupId>
                    <artifactId>XmlSchema</artifactId>
                    <version>1.4.3</version>
                </dependency>
                <dependency>
            </dependencies>
    <build>
        <sourceDirectory>src</sourceDirectory>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.0</version>
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <configuration>
                    <archive>
                        <manifest>
                    <mainClass>com.myproject.main.MainClass</mainClass>
                        </manifest>
                    </archive>
                </configuration>
            </plugin>
    </build>
</project>

When i execute the mvn compile and mvn install, the project works fine and it also generates the jar. But when i try to run the jar [using java -jar MyProject.jar], i get an error which says: Exception in thread "main" java.lang.NoClassDefFoundError and this is because maven is not able to add the dependent jar specified in the section. [it is not available during run time]

Could anybody let me know the best possible way for me to copy the systemPath jars to the jar that is being generated by maven?

I looked at maven-shade-plugin and maven-assembly-plugin and could not find much luck with both of them. Any help would be appreciated!

Answer 1

Try to add this to your maven-jar-plugin configuration

<addClasspath>true</addClasspath>
<classpathPrefix>*path to dependencies*</classpathPrefix>

Also to manage your dependencies you can use Maven dependency plugin

Answer 2

In the build section of your pom, you can use:

 <build>
    <plugins>
    <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-shade-plugin</artifactId>
        <version>2.4.2</version>
        <executions>
            <execution>
                 <phase>package</phase>
                 <goals>
                      <goal>shade</goal>
                 </goals>
                 <configuration>
                    <artifactSet>
                <includes>
                <include>com:library:**</include>
                </artifactSet>
              </configuration>
        </execution>
        </executions>
     </plugin>
</plugins>
</build>

Then, on the command line, you can run mvn package , it will show in the output which jars it is excluding. Then, you can include selected jars accordingly. If you then get NoClassDefFoundError , you may need to point Java to your class, by for example using com.company.Main as an argument to the java command.