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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.


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