---

id: functions-package-java title: Package Java Functions sidebar_label: “Package Java Functions”

:::note

For the runtime Java version, refer to Pulsar Runtime Java Version Recommendation according to your target Pulsar version.

:::

To package a Java function, complete the following steps.

1. Create a new maven project with a pom file. In the following code sample, the value of mainClass is your package name.

   
    <?xml version="1.0" encoding="UTF-8"?>
    <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>
   
        <groupId>java-function</groupId>
        <artifactId>java-function</artifactId>
        <version>1.0-SNAPSHOT</version>
   
        <dependencies>
            <dependency>
                <groupId>org.apache.pulsar</groupId>
                <artifactId>pulsar-functions-api</artifactId>
                <version>2.10.0</version>
            </dependency>
        </dependencies>
   
        <build>
            <plugins>
                <plugin>
                    <artifactId>maven-assembly-plugin</artifactId>
                    <configuration>
                        <appendAssemblyId>false</appendAssemblyId>
                        <descriptorRefs>
                            <descriptorRef>jar-with-dependencies</descriptorRef>
                        </descriptorRefs>
                        <archive>
                        <manifest>
                            <mainClass>org.example.test.ExclamationFunction</mainClass>
                        </manifest>
                    </archive>
                    </configuration>
                    <executions>
                        <execution>
                            <id>make-assembly</id>
                            <phase>package</phase>
                            <goals>
                                <goal>assembly</goal>
                            </goals>
                        </execution>
                    </executions>
                </plugin>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <configuration>
                        <release>17</release>
                    </configuration>
                </plugin>
            </plugins>
        </build>
   
    </project>
   
   

2. Package your Java function.

   
    mvn package
   
   

   After the Java function is packaged, a target directory is created automatically. Open the target directory to check if there is a JAR package similar to java-function-1.0-SNAPSHOT.jar.

3. Copy the packaged jar file to the Pulsar image.

   
    docker exec -it [CONTAINER ID] /bin/bash
    docker cp <path of java-function-1.0-SNAPSHOT.jar>  CONTAINER ID:/pulsar
   
   

4. Run the Java function using the following command.

   
    ./bin/pulsar-admin functions localrun \
    --classname org.example.test.ExclamationFunction \
    --jar java-function-1.0-SNAPSHOT.jar \
    --inputs persistent://public/default/my-topic-1 \
    --output persistent://public/default/test-1 \
    --tenant public \
    --namespace default \
    --name JavaFunction
   
   

   The following log indicates that the Java function starts successfully.

    ...
    07:55:03.724 [main] INFO  org.apache.pulsar.functions.runtime.ProcessRuntime - Started process successfully
    ...