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Use ANT to Build a JAR with version/build numberTag(s): Environment


  • Download ANT from http://ant.apache.org/bindownload.cgi
  • Unzip into the root of C: (Windows), rename the folder to \Ant
  • Create a file call antenv.cmd. Before using ANT, you must execute this file to set up the environment. You may need to adjust the values according to your installation! 
    set ANT_HOME=c:\ant
set JAVA_HOME=C:\Progra~1\Java\jdk1.5.0
set PATH=%ANT_HOME%\bin;%JAVA_HOME%\bin;%path%
  • Create a simple Hello class as shown below (you need have a package). 
    package howto;
public class Hello {
   public static void main( String[] args ){
        System.out.println( "Hello World" );
    }
}
  • Execute your antenv.cmd to set the environment
  • Compile your Hello class and make a jar to check if your environment is ok. 
    > javac howto/Hello.java
> jar -cvf hello.jar howto/Hello.class
added manifest
adding: howto/hello.class(in = 415) (out= 284) (deflated 31%)
> java -cp hello.jar howto.Hello
Hello World
  • Create a build.xml which is the default ant build file ...
  • ... and load it into your favorite editor. Type the following ant script and save it. 
    <project default="buildHello">
  <target name="compile">
    <javac srcdir="." />
  </target>
  
  <target name="buildHello" depends="compile" />
</project>
    Go back to the DOS shell and launch Ant with 
    > ant compile  
Buildfile: build.xml

compile:
    [javac] Compiling 1 source file
  • Go back to the editor and add the jar building command. The target compile is also executed since the target jar depends on it. 
    <project default="buildHello">
  <target name="compile">
    <javac srcdir="." />
  </target>
  
  <target name="jar" depends="compile">
    <jar destfile="hello.jar"
         basedir="."
         includes="**/*.class"
         />
  </target>
  
  <target name="buildHello" depends="compile,jar" />
</project>
  • Execute your Ant script : 
    > ant jar
Buildfile: build.xml

compile:

jar:
      [jar] Building jar: /Dev/hello.jar

BUILD SUCCESSFUL
Total time: 2 seconds
$ jar -tvf hello.jar
jar -tvf hello.jar
     0 Wed May 03 17:06:32 EST 2006 META-INF/
    55 Wed May 03 17:06:32 EST 2006 META-INF/MANIFEST.MF
    55 Wed May 03 17:06:32 EST 2006 howto/
   335 Wed May 03 16:36:16 EST 2006 howto/Hello.class
  • Try your new Jar file 
    > java -cp Hello.jar howto.Hello
Hello World
  • Make your Jar auto-executable by specifying the Main class into a MANIFEST.MF file to be included in the Jar. Add the following lines to build.xml 
    <project default="buildHello">
  <target name="compile">
    <javac srcdir="." />
  </target>
  
  <target name="jar" depends="compile">
     <delete file="hello.jar"/>
     <delete file="MANIFEST.MF"/>
     <manifest file="MANIFEST.MF">
        <attribute name="Built-By" value="${user.name}"/>
        <attribute name="Main-Class" value="howto.Hello"/>
    </manifest>
  
      <jar destfile="hello.jar"
           basedir="."
           includes="**/*.class"
           manifest="MANIFEST.MF"
           />
  </target>
  
  <target name="buildHello" depends="compile,jar" />
</project>
  • Now you can launch Hello with only 
    > ant jar
...
> java -jar hello.jar
Hello World
  • Add a build number with the Ant task buildnumber . Ant will create (if necessary) and increment a property in a file called build.num (so you need to keep it!). Then a property, build.number, is available in your Ant script. The version number is also a property. Here it is hard-coded in the script but you can read it from a file. 
    <project default="buildHello">
  <target name="compile">
    <javac srcdir="." />
  </target>
  
  <target name="jar" depends="compile">
     <delete file="hello.jar"/>
     <delete file="MANIFEST.MF"/>
     <property name="version.num" value="1.00"/>
     <buildnumber file="build.num"/>
     
     <manifest file="MANIFEST.MF">
        <attribute name="Built-By" value="${user.name}"/>
        <attribute name="Main-Class" value="howto.Hello"/>
        <attribute name="Implementation-Version" 
                     value="${version.num}-b${build.number}"/> 
    </manifest>
  
      <jar destfile="hello.jar"
           basedir="."
           includes="**/*.class"
           manifest="MANIFEST.MF"
           />
  </target>
  
  <target name="buildHello" depends="compile,jar" />
</project>
  • If you examine the MANIFEST.MF, you now see a new entry 
    Implementation-Version: 1.00-b1
  • and after the next build operation, the entry will be 
    Implementation-Version: 1.00-b2
  • Modify the Hello class to read the Implementation-Version information and display it. 
    package howto;

public class Hello {
   public static void main( String[] args ){
       System.out.println( "Hello World ");
       System.out.println("version : " +
         Hello.class.getPackage().getImplementationVersion() );
    }
}
  • Finally we add a target to cleanup and the main target to build everything to the build.xml file. 
    <project default="buildHello">
  <target name="compile">
    <javac srcdir="." />
  </target>
  
  <target name="jar">
     <delete file="hello.jar"/>
     <property name="version.num" value="1.00"/>
     <buildnumber file="build.num"/>
     
     <manifest file="MANIFEST.MF">
        <attribute name="Built-By" value="${user.name}"/>
        <attribute name="Main-Class" value="howto.Hello"/>
        <attribute name="Implementation-Version" 
                 value="${version.num}-b${build.number}"/>         
    </manifest>
  
      <jar destfile="hello.jar"
           basedir="."
           includes="**/*.class"
           manifest="MANIFEST.MF"
           />
  </target>
  
  <target name="cleanup">
       <delete>
         <fileset dir="." includes="**/*.class"/>
         <fileset file="MANIFEST.MF"/>
       </delete>  
  </target>
  
  <target name="buildHello" depends="compile,jar,cleanup" />
</project>
  • Build and launch the Hello class 
    > ant buildHello
...
> java -jar hello.jar
Hello World
version : 1.00-b3
    b3 == build #3 (if it's your third build !)

    Build number is great but a Built date is useful too! 

    ...
 <target name="jar">
   <delete file="hello.jar"/>
   <property name="version.num" value="1.00"/>
   <buildnumber file="build.num"/>
   <tstamp>
     <format property="TODAY" pattern="yyyy-MM-dd HH:mm:ss" />
   </tstamp>

   <manifest file="MANIFEST.MF">
      <attribute name="Built-By" value="${user.name}"/>
      <attribute name="Main-Class" value="howto.Hello"/>
      <attribute name="Implementation-Version" 
             value="${version.num}-b${build.number}"/>   
      <attribute name="Built-Date" value="${TODAY}"/>                 
  </manifest>

  <jar destfile="hello.jar"
       basedir="."
       includes="**/*.class"
       manifest="MANIFEST.MF"
       />
</target>

    See also this Howto.