Reducing SpringBoot Jar Size by Excluding Unnecessary lib Dependencies

When a SpringBoot application is deployed to a public cloud server, the generated JAR often exceeds 18 MB because the BOOT‑INF/lib directory contains all external dependencies, which makes incremental updates and runtime tuning difficult.

Step 1: Build the project normally with mvn clean install, unzip the resulting JAR, and copy the BOOT‑INF/lib folder to the target machine.

Step 2: Modify pom.xml to repackage the JAR without the lib folder. Example configuration:

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <configuration>
                <mainClass>com.johnnian.App</mainClass>
                <layout>ZIP</layout>
                <includes>
                    <include>
                        <groupId>nothing</groupId>
                        <artifactId>nothing</artifactId>
                    </include>
                </includes>
            </configuration>
            <executions>
                <execution>
                    <goals>
                        <goal>repackage</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

After updating the POM, run mvn clean install again; the new JAR will be dramatically smaller because external JARs are no longer packaged.

Step 3: Run the reduced JAR by specifying the external lib directory with the SpringBoot loader path:

java -Dloader.path=/path/to/lib -jar /path/to/springboot-jsp-0.0.1-SNAPSHOT.jar

Alternatively, you can copy required dependencies using Maven:

mvn dependency:copy-dependencies -DoutputDirectory=F:\ideaWorkPlace\AnalysisEngine\lib -DincludeScope=runtime

Final directory layout should look like:

├── lib   # external libraries
└── springboot-jsp-0.0.1-SNAPSHOT.jar

Notes: the /path/to placeholder must be replaced with the actual file system path. Once the architecture is fixed, most JARs remain unchanged, and only business logic needs recompilation, greatly improving deployment efficiency.