Resolving Maven JAR Packaging and Dependency Issues for Third‑Party Consumption

The author encountered a requirement to deliver a utility JAR to a third‑party that could not access the private repository, leading to import failures and missing dependencies.

1. Maven common commands – A quick reference of frequently used Maven goals such as clean, validate, compile, test, package, install, verify, site, and deploy is provided.

2. Unable to import after packaging – After building the project with mvn package, the generated JAR could be copied to the third‑party's libs directory and referenced with systemPath, but the IDE still reported import errors because the default packaging plugin creates an executable JAR, not a library.

Solution: replace the packaging plugin with the standard maven-compiler-plugin:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-compiler-plugin</artifactId>
    <version>3.8.1</version>
    <configuration>
        <source>1.8</source>
        <target>1.8</target>
        <encoding>UTF-8</encoding>
    </configuration>
</plugin>

After rebuilding, the import error disappears, but a new NoClassDefFoundError for org/apache/commons/codec/binary/Base64 appears, indicating a missing transitive dependency.

3. Missing additional JAR dependencies – The original JAR (≈14 KB) does not contain the commons-codec library (≈339 KB). Two approaches are suggested: bundle the dependencies into the JAR or ask the third‑party to add them manually.

Recommended solution: use the maven-assembly-plugin to create a “jar‑with‑dependencies” package.

<dependency>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-assembly-plugin</artifactId>
    <version>3.0.0</version>
</dependency>

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-assembly-plugin</artifactId>
    <version>2.4.1</version>
    <configuration>
        <descriptorRefs>
            <descriptorRef>jar-with-dependencies</descriptorRef>
        </descriptorRefs>
    </configuration>
</plugin>

Running mvn assembly:assembly produces a large JAR (≈15.4 MB) that includes all required dependencies, which can be safely handed to the third‑party without further errors.

The article concludes with reference links to a CSDN blog and the official Maven dependency mechanism guide.