Introduction To ANT

Introduction to Ant

Author: Rajesh Kumar

www.scmGalaxy.com

Agenda

What is ANT?
Installation
Sample build.xml
Executing ant script
Closer look at the structure of ANT file
Advantages of using ANT
Packaging - JAR, WAR, EAR

What is ANT?

Another Neat Tool
Java-based build tool
Like make, without make's wrinkles ?
An open source Apache Jakarta project

http://ant.apache.org/

Implemented in Java, implemented for Java

Installation

Download the binaries from

http://jakarta.apache.org/ant/index.html

Unzip to a suitable directory
Set ANT_HOME = path_to_ant_folder
Append PATH=%PATH%;%ANT_HOME%\bin to the PATH environment variable
Append the .jar files in /path_to_ant/lib/ to the CLASSPATH environment variable
Ensure that JAVA_HOME points to the location of the JDK installation on your machine & /path_to_ jdk/lib/* is a part of the CLASSPATH environment variable

Working with ANT

Every project using ANT will have a build file - build.xml

<?xml version="1.0"?> 
<project name="test" default="compile" basedir="."> 
     <property name="src" value="."/> 
     <property name="build" value="build"/>
     <target name="init">  
          <mkdir dir="${build}"/>
     </target>
     
	<target name="compile" depends="init"> 
          <!-- Compile the java code -->          
          <javac srcdir="${src}" destdir="${build}"/> 
     </target>
</project>

A simple build.xml

<?xml version="1.0"?>

XML declaration specifying version of XML used. All XML constraints hold good for build.xml

<project name= "test" default="compile" basedir=".">

project - root element of build.xml
It has 3 attributes

name - name of project
default - (mandatory) default target when no target is specified
basedir - directory from which any relative directories within build.xml are referenced from

A simple build.xml [Contd.]


							<property name="src" value="."/> 
<property name="build" value="build"/>

Property declaration is like user-defined variables to use within the build file
It has 2 attributes

name - name of property
value - desired value of the property

To reference a property, ${property_name} - ${src}
Built in properties that ANT provides :

basedir
ant.file
ant.version
ant.project.name
ant.java.version

A simple build.xml [Contd.]


							<target name="init">
     <mkdir dir="${build}"/>
 </target>

target element is a wrapper for a sequence of actions
Has the following attributes

name - (mandatory) Name used to reference this target from within the file or from command line
description - short description of this target
if - to conditionally execute contents of target based on the value of a property
unless- converse of if

A simple build.xml [Contd.]


							<target name="compile" depends="init"> 
		<javac srcdir="${src}" destdir="${build}"/> 
  </target>

depends - comma separated list of all the targets on which this target depends, i.e, targets that must be executed prior to the execution of this target

javac element is a task which is performed under the target compile
By default, only those .java input files that have a more recent timestamp than their corresponding .class output files will be compiled

Executing ant script

ant [options] [target [target2 [target3] ...]]

Options:

-help	print this message
-projecthelp	print project help information
-version	print the version information and exit
-diagnostics	print information that might be helpful to diagnose or report problems.
-quiet, -q	be extra quiet
-verbose, -v	be extra verbose

-debug	print debugging information
-emacs	produce logging information without adornments
-logfile <file>	use given file for log
-l <file>	""
-logger <classname>	the class which is to perform logging
-listener <classname>	add an instance of class as a project listener
-buildfile <file>	use given buildfile

-file <file>	""
-f <file>	""
-D<property>=<value>	use value for given property
-propertyfile	taking precedence
-inputhandler <class>	the class which will handle input requests
-find <file> <name>	load all properties from file with -D properties search for buildfile towards the root of the filesystem and use it

Path-like structures

- classpath

Wherever path-like values need to be specified, a nested element can be used :

<classpath>
		<pathelement path="${classpath}"/> 	
		<pathelement location="lib/helper.jar"/>
	</classpath>
	<classpath path ="${classpath}"/>

location - specifies a single file or directory relative to the project's base directory or an absolute filename
path - accepts ":" or ";" separated lists of locations

Path-like structures

- path


					<path id="project.class.path">
	  <path refid="base.path"/>
    <pathelement location="lib/"/>
 </path>
 <classpath refid="project.class.path"/>

To use the same path-like structure for several tasks, you can define them with a <path> element at the same level as targets, and reference them via their id attribute

Path-like structures

- dirset, fileset,filelist


						 <classpath>
      <pathelement path="${classpath}"/>
      <fileset dir="lib">
        <include name="**/*.jar"/>
      </fileset>
      <pathelement location="classes"/>
      <dirset dir="${build.dir}">
        <include name="apps/**/classes"/>
        <exclude name="apps/**/*Test*"/>
      </dirset>
      <filelist dir="${src.dir}" files="foo.xml,bar.xml"/>
</classpath>

Tasks

Piece of code that can be executed
Built-in tasks :

javac, java, javadoc, javah, junit
mkdir, copy, move, delete, fileset
jar, war, zip, unjar, unwar, unzip
echo, cvs, exec
ant, antcall

You can also write your own tasks

javac


						<javac debug="${debug}" 
        optimize="${optimize}"  
        deprecation="${deprecation}" 
        destdir="${build.dest}" 
        includes="com/**" excludes="**/*.xml">
 		<src path="${src.dir}" />   
		<classpath refid="classpath" />   
 </javac>

Compiles a java source tree
Source & destination directory recursively scanned for .java files to compile
By default only check made for rebuild is existence / modification time
To define any other java class dependencies use task <depend>

Building subprojects

- ant


					 <ant antfile="subproject/subbuild.xml"    
	    dir="subproject" 
       target="compile"/>
 <ant inheritAll="false"      
	   antfile="subproject/subbuild.xml">
    <property name="output.type" value="html"/>
</ant>

Runs Ant on supplied build file
This task must not be used outside of a target if it invokes the same build file that it is part of

Calling other targets

- antcall


					 	<target name="default">
    <antcall target="doSomethingElse">
      <param name="param1" value="value"/>
    </antcall>
  </target>
  <target name="doSomethingElse">
    <echo message="param1=${param1}"/>
  </target>

Call another target within the same build-file (optionally specifying properties)
This task must no be used outside of a target

Advantages

Ease of use

Configuration files are XML based
Same config file (build.xml) can be used across platforms

Platform independent
Special support for Java

Easy to create JavaDocs, WAR & JAR files

Built-in support for

JUnit
FTP
CVS

Advantages [Contd.]

Particularly good for automating complicated repetitive tasks which is what most build processes are all about!
ANT can be integrated with most Java IDEs