Building a JAR Executable with Maven and Spring

I have a Spring MVC web project. I want to generate some xml files based on some data stored in my database. This program will be run once or a few times everyday. As the data size grows, the program may take longer to run. The best way to do this is to write a JAR executable and feed it to Amazon to Elastic MapReduce.

We will set up a small JAR project with Maven below.

First generate a Maven project called maventest. If you do not have maven set up, read Install Maven 3 on Amazon EC2 Ubuntu.

mvn archetype:generate -DarchetypeGroupId=org.apache.maven.archetypes -DgroupId=com.mycompany.maventest -DartifactId=maventest

Resources files are located in src/main/resources/.

Spring requires a context xml file that defines how classes are instantiated. Create a file called applicationContext.xml in src/main/resources.

Paste the following into the applicationContext.xml file



Create a file called jdbc.properties in src/main/resources. We will be connecting to a MySQL database.



My whole project is called myproject. It has the Spring MVC web project has the package name   com.mycompany.package1 and artifactId mywebproject. This cron program will have the package name com.mycompany.package2 with artifactId cron.

We will use the maven-jar-plugin to define the location of our main class.

< plugin>
< groupId>org.apache.maven.plugins< /groupId>
< artifactId>maven-jar-plugin< /artifactId>
< configuration>
  < archive>
    < manifest>
      < mainClass>com.mycompany.package2.App< /mainClass>
    < /manifest>
  < /archive>
< /configuration>
< /plugin>

In order to package all the dependencies as one jar file, we will use maven-shade-plugin. Sometimes, spring.schemas and spring.handlers files can be overwritten. Examine the transformers tag below to see that the content of these files will be appended.

We will now include all the dependencies in the pom.xml file.

Package the project (It's useful to understand what's compile, package, install and deploy)

mvn clean package

If the package command fails, it may be complaining that it can't find the com.mycompany.package1.mywebproject project.

You can do a mvn:install for mywebproject. This will install mywebproject to the local maven repository. It is located under /Users/{your_name}/.m2. Remember to compile mywebproject as JAR by setting it in the pom.xml. If you ever suspect that some classes are missing or the build is not quite correct. It's highly likely that mywebproject in the local repository is not up-to-date.

The jar file is located in the target folder. Run the jar

java -jar maventest-1-0-SNAPSHOT

Unable to locate resource hector-core-1.1-3-SNAPSHOT.jar

If you ever get the following message regarding the hector client, you can install it manually by download the file from the hectorclient website.

Error message:

Unable to locate resource https://oss.sonatype.org/content/groups/public/org/hectorclient/hector-core/1.1-3-SNAPSHOT/hector-core-1.1-3-SNAPSHOT.jar

Installation command:

mvn install:install-file -DgroupId=org.hectorclient -DartifactId=hector-core -Dversion=1.1-3-SNAPSHOT -Dpackaging=jar -Dfile=~/Downloads/hector-core-1.1-3-20130112.031550-9.jar

Maven - A sample pom.xml for java jar executable

The following provides a sample JAR executable.

It uses hiberate, spring, mysql.

The class that contains the Main function is specified in the "mainClass" tag.

Sample pom.xml

< ?xml version="1.0"?>

<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"

    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

  <modelVersion>4.0.0</modelVersion>

  <groupId>com.mycompany.generator</groupId>

  <artifactId>onix-generator</artifactId>

  <version>1.0-SNAPSHOT</version>

  <name>onix-generator</name>

  <url>http://maven.apache.org</url>

  <properties>

    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

    <spring.version>3.2.1.RELEASE</spring.version>

    <jdbc.groupId>mysql</jdbc.groupId>

        <jdbc.artifactId>mysql-connector-java</jdbc.artifactId>

        <jdbc.version>5.1.14</jdbc.version>

        <hibernate.version>3.6.10.Final</hibernate.version>

        <javamail.version>1.4.1</javamail.version>

        <log4j.version>1.2.16</log4j.version>

  </properties>

  <build>

    <plugins>

      <plugin>

        <groupId>org.apache.maven.plugins</groupId>

        <artifactId>maven-jar-plugin</artifactId>

        <configuration>

          <archive>

            <manifest>

              <addClasspath>true</addClasspath>

              <mainClass>com.mycompany.generator.App</mainClass>

              <packageName>com.mycompany.generator</packageName>

            </manifest>

          </archive>

        </configuration>

      </plugin>

      <plugin>

    <groupId>org.apache.maven.plugins</groupId>

    <artifactId>maven-compiler-plugin</artifactId>

    <configuration>

      <source>1.7</source>

      <target>1.7</target>

      </configuration>

      </plugin>

    </plugins>

  </build>

  <dependencies>

    <dependency>

      <groupId>junit</groupId>

      <artifactId>junit</artifactId>

      <version>3.8.1</version>

      <scope>test</scope>

    </dependency>

    <dependency>

      <groupId>${jdbc.groupId}</groupId>

      <artifactId>${jdbc.artifactId}</artifactId>

      <version>${jdbc.version}</version>

    </dependency>

    <dependency>

            <groupId>log4j</groupId>

            <artifactId>log4j</artifactId>

            <version>${log4j.version}</version>

            <exclusions>

                <exclusion>

                    <artifactId>mail</artifactId>

                    <groupId>javax.mail</groupId>

                </exclusion>

                <exclusion>

                    <artifactId>jms</artifactId>

                    <groupId>javax.jms</groupId>

                </exclusion>

                <exclusion>

                    <artifactId>jmxtools</artifactId>

                    <groupId>com.sun.jdmk</groupId>

                </exclusion>

                <exclusion>

                    <artifactId>jmxri</artifactId>

                    <groupId>com.sun.jmx</groupId>

                </exclusion>

            </exclusions>

        </dependency>

        <dependency>

            <groupId>org.springframework</groupId>

            <artifactId>spring-jdbc</artifactId>

            <version>${spring.version}</version>

        </dependency>

        <dependency>

            <groupId>org.springframework</groupId>

            <artifactId>spring-orm</artifactId>

            <version>${spring.version}</version>

        </dependency>

        <dependency>

            <groupId>org.springframework</groupId>

            <artifactId>spring-aspects</artifactId>

            <version>${spring.version}</version>

        </dependency>

        <dependency>

            <groupId>org.springframework</groupId>

            <artifactId>spring-context-support</artifactId>

            <version>${spring.version}</version>

        </dependency>

        <dependency>

        <groupId>com.mycompany.generator</groupId>

        <artifactId>epubserver</artifactId>

        <version>1.0-SNAPSHOT</version>

        <classifier>classes</classifier>

        </dependency>

  </dependencies>

</project>

You can generate an executable by running

mvn clean package

The jar file will be located in the target folder. You can run the executable by:

java -jar {name_of_jar}

Maven javac: invalid target release: 1.7

When I try to compile my maven project by running "mvn package", I get the following error

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:2.3.2:compile (default-compile) on project onix-generator: Compilation failure
[ERROR] Failure executing javac, but could not parse the error:
[ERROR] javac: invalid target release: 1.7
[ERROR] Usage: javac
[ERROR] use -help for a list of possible options

1) Check your Java version:

java -version

java version "1.7.0_09"
Java(TM) SE Runtime Environment (build 1.7.0_09-b05)
Java HotSpot(TM) 64-Bit Server VM (build 23.5-b02, mixed mode) 

2) Check javac version:

javac -version

javac 1.7.0_09

3) Check $JAVA_HOME

Make sure it points to the java bin directory.

How to create a Maven project

First install Maven - Read Install Maven 3 on Amazon EC2 Ubuntu.

Create a folder anywhere you like. cd into the directory.

Create a Maven project

mvn archetype:generate -DarchetypeGroupId=org.apache.maven.archetypes -DgroupId=com.mycompany.maventest -DartifactId=maventest

The CLI will prompt for a few options:

1.) Choose a number or apply filter (format: [groupId:]artifactId, case sensitive contains): 284:

Push Enter. We will use the default 284.

remote -> org.apache.maven.archetypes:maven-archetype-quickstart (An archetype which contains a sample Maven project.)

2.) Choose org.apache.maven.archetypes:maven-archetype-quickstart version:

Choose 1.1 (Number 6).

3.) Define value for property 'version':  1.0-SNAPSHOT: :

You can leave the version "1.0-SNAPSHOT" as the default value.

4.) Confirm properties configuration:

Push Enter.


You should see a folder created.