Ant – an introduction

Ant is a Java based build tool developed as part of the Apache Jakarta project. You can get it from the Ant home site: ant.apache.org. At first the usefulness of Ant may not be readily apparent, but after using it for awhile on even small projects you may be surprised at how much you come to rely on it. For example, the ability to build files into specific directories, generate JavaDoc and package classes into JAR files for deployment all in one keystroke is extremely powerful. Here is a non-exhaustive list of what Ant can do:

  • Extract source from a version control system
  • Create directories
  • Delete directories
  • Compile code
  • Generate JavaDoc
  • Jar files
  • Copy files
  • Generate e-mail
  • FTP files
  • Execute SQL statements
  • Run unit tests

After downloading and unzipping the download contents, copy the Ant directory to the root of your C:\ drive, so the path is “C:\Ant”. You can install it anywhere you want, but this is most convenient. We also have to set up some environment variables so that the system can find Ant when we need it. You need to add System Variable called ANT_HOME, set this to the directory where you put Ant, in this case “C: \Ant”. Make sure there is also a System Variable called JAVA_HOME that point to your Java SDK directory.

We’re almost done. Now all you have to do is add the above variables to your path. Look for the “PATH” environment variable under System Variables and click “Edit”. Add this to the end of the path:

;%JAVA_HOME%\bin;%ANT_HOME%\bin

Notice that entries in the path on Windows are delimited by “;”. Now restart your machine to make sure the environment variables stick. We’re almost ready to test our installation. Open up a command window and type: ant. If the above steps went well, then you should see your first Ant error message:

D:\>ant

Buildfile: build.xml does not exist!
Build failed

This means that the installation worked. If you got anything other than this, then more than likely one of the above installation steps weren’t performed.

Ant requires a couple of things to run: Java source files (obviously), and a build file. First we’re going to create a really simple Java program for Ant to build.

public class AntTest{
public AntTest(){
System.out.println(“Isn’t Ant cool?”);
}

public static void main(String[] args){
new AntTest();
}
}

Don’t try to compile it yet, we’re gonna let Ant do that. The next thing we need is the build file.

<project name=”AntExamplel” default=”dist” basedir=”.”>
<!– set global properties for this build –>
<property name=”src” value=”.”/>
<property name=”build” value=”build”/>
<property name=”dist” value=”dist”/>

<target name=”init”>
<!– Create the time stamp –>
<tstamp/>

<!– Create the build directory structure used by compile –>
<mkdir dir=”${build}”/>
</target>

<target name=”compile” depends=”init”>
<!– Compile the java code from ${src} into ${build} –>
<javac srcdir=”${src}” destdir=”${build}”/>
</target>

<target name=”dist” depends=”compile”>
<!– Create the ${dist}/lib directory –>
<mkdir dir=”${dist}/lib”/>

<!– Put everything in ${build} into the AntTutorial-${DSTAMP}.jar file –>
<jar jarfile=”${dist}/lib/AntExample-${DSTAMP}.jar” basedir=”${build}”/>
</target>

<target name=”clean”>
<!– Delete the ${build} and ${dist} directory trees –>
<delete dir=”${build}”/>

<delete dir=”${dist}”/>
</target>
</project>

Make sure that you saved the build.xml file in the same directory as the Java source file. We’re not going to get into what the build file is actually doing yet, so just trust me…

Now, in your command window, cd to the directory where the Java source and the build file are saved (a lot of tutorials leave this step out, strangely enough) and type “ant“. Hopefully you will see the BUILD SUCCESSFUL message at the bottom. Now check out the directory. You’ll notice that there are two new directories: “build“, and “dist“. These directories were built by Ant. The “build” directory will include the compiled Java class file(s) and the “dist” directory will contain a .jar file with our project name and a timestamp.

Reference: http://ant.apache.org/manual/index.html

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