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Apache Ant
Java-Based Build Tool
Making your builds boring…
Building projects should be easy and
standardized. You should not be spending a
substantial amount of your project time on
builds. Builds should just work!
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Introduction to Ant
• Ant is a “build tool” – especially useful to
compile, package, deploy Java projects
• It can do much more - file operations, version
control/CVS, XML validations/transforms, run
system commands, custom tasks, etc
• Ant is suitable also for all kinds of Java-unrelated
file manipulations, e.g. preprocessing static stuff
in Web publishing
• Ant’s alternatives are “batch” files under
Windows, Makefile-s or shellscripts under UNIX.
Build scripts may be written in other scripting
languages as well
Typical Things to Build
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Classes
JARs
WARs
EARs
JavaDocs
Documentation HTML/PDF
Ant in Java Projects
• Even when there is IDE build environment, it is
useful to have Ant script to build and deploy
(everything is transparent there)
• In big projects build scripts are usually written by
“Technical Designer” or qualified developer
• Other developers ideally just need to remember a
few commands, e.g.
ant -projecthelp (lists targets and their descriptions)
ant junit (rebuild and run JUnit tests)
ant deploy (build and deploy for a system test)
Ant and IDE tools
• They are complementary: Ant build scripts can
automate all kinds of build processes
• Use IDE (e.g. Eclipse) for editing, unit-testing
and version-controlling code; use Ant for doing
more complex development tasks, e.g.
deployments and system tests
• Eclipse plugins can solve similar issues as Ant
can, but Ant is free and easier to standardize
Ant Features
• Build-scripts are written using a special XML
syntax
• “Ant tasks” represent object-oriented approach to
build process. Tasks can inherit from each other.
• Build-file language does not have flow control
features:
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loops/iterators, if-constructs, try-catch constructs
• Instead it is based on recursive nature of Ant’s
tasks and Ant’s datatypes filesets, patterns, filters,
mappers, etc
Build File
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XML format
Typically in project root directory
Default name: build.xml
Declarative - define steps, not scripty details
Defines a single project
A project contains targets
Targets contain tasks
Projects
• A project has three attributes:
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name - the name of the project
default - the default target to use when no target is supplied
basedir - the base directory from which all path calculations
are done
• Each project defines one or more targets
<?xml version="1.0" ?>
<project name="sample" default="deploy" basedir=".">
<target name="clean" description="Removes build artifacts">
…
</target>
</project>
Targets
• A target can depend on other targets
<target name="A"/>
<target name="B" depends="A"/>
<target name="C" depends="B"/>
>ant D
A
<target name="D“ depends="C,B,A"/>
B
C
D
Dependency resolution
• A target has the following attributes:
• name - the name of the target
• depends - a comma-separated list of names of targets on which
this target depends
• if - the name of the property that must be set in order for this
target to execute
• unless - the name of the property that must not be set in order for
this target to execute
• description - a short description of this target's function
Tasks
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A task is a piece of code that can be executed
Tasks have a common structure:
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There is a set of built-in tasks:
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<name attribute1="value1" attribute2="value2" ... />
<mkdir>, <copy>, <delete>
<javac>, <java>
<jar>, <zip>
many more…
It is very easy to write your own task:
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Extend a org.apache.tools.ant.Task class
Implement specific stuff like attributes, nested tasks etc.
Write a public void execute method, with no
arguments, that throws a BuildException. This method
implements the task itself.
Properties
• A project can have a set of properties
• ${property.name} to access property value
• Properties can be defined:
• In Ant file itself (name/value)
<property name="site" value="sample"/>
• In one or more external properties file
<property file="sites/${site}/config.properties”
prefix="site"/>
• In the command line
> ant
-Dappname=newstuff
jar
• Environment variables can be accessed
<property environment="env"/>
<echo message="Number of Processors=${env.NUMBER_OF_PROCESSORS}"/>
Ant Data Types
• Commonly used built-in data types:
• Path
<path id="anttask.compile.classpath">
<pathelement location="${lucene.jar}"/>
<pathelement location="${jtidy.jar}"/>
</path>
• Ordered list of path
elements, analogous to
Java CLASSPATH, contains files and/or directories
• Fileset
<fileset dir="web" excludes="search.jsp"/>
<fileset dir="${build.dir}/${site}" includes="*.jsp"/>
• Unordered set of files from a single root directory
• Patternset
<patternset id=“java.files.pattern” includes=“**/*.java”/>
<fileset dir="src">
<patternset refid=“java.files.pattern”/>
</fileset>
• Selectors, Filterset, and others…
Example build file
<project name="MyProject" default="dist" basedir="."><description>Simple example build file</description>

<property name="src" location="src"/>
<property name="build" location="build"/>
<property name="dist" location="dist"/>
<target name="init">

<mkdir dir="${build}"/>
</target>
<target name="compile" depends="init" description="compile the source " >

<javac srcdir="${src}" destdir="${build}"/>
</target>
<target name="dist" depends="compile" description="generate the distribution" >
<mkdir dir="${dist}/lib"/>

<jar jarfile="${dist}/lib/MyProject.jar" basedir="${build}"/>
</target>
<target name="clean“ description="clean up" >

<delete dir="${build}"/>
<delete dir="${dist}"/>
</target>
</project>
Installing Ant
• Download from http://ant.apache.org
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current version 1.7.0 / 2006-12-19
• Precondition – install J2SE (or JRE) and set
variable %JAVA_HOME%
• Unpack Ant’s installation and set variable
%ANT_HOME%
• Add %ANT_HOME%\bin to your %PATH% variable
to enable running “ant.bat” utility from any DOS
window
Running Ant Targets
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Ant targets can be executed from command line:
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Execute default target:
> ant
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Execute specific target:
> ant deploy-jboss
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Execute multiple targets:
> ant test-common generate-test-reports
> ant deploy-jboss -Dsite=personal
Buildfile: build.xml
init:
[echo] Building for personal site.
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deploy-jboss:
[copy] Copying 1 file to /Users/erik/jboss-3.0.0/server/default/deploy
BUILD SUCCESSFUL
Total time: 18 seconds
Debugging Ant
• By default, Ant’s messages for failed tasks might
be insufficient. You can easily make Ant more
verbose to see what it is doing:
ant -verbose taskname
ant -debug taskname (very verbose)
• These will show each elementary action
performed by the build process
File Tasks
Task Name
Description
mkdir
Creates a directory. Non-existent parent directories are created, when
necessary.
delete
Deletes either a single file, all files and sub-directories in a specified
directory, or a set of files specified by one or more FileSets.
copy
Copies a file or Fileset to a new file or directory.
move
Moves a file to a new file or directory, or a set(s) of file(s) to a new
directory.
chmod
Changes the permissions of a file or all files inside the specified
directories. Currently, it has effect only under Unix. The permissions are
also UNIX style, like the arguments for the chmod command.
get
Gets a file from a URL.
More tasks: concat, replace, chown, sync, tempfile, touch,…
More Tasks…
• <javac>
Compiles a Java
source tree
• <jar>
Jars a set of files
• <war>
Creates Web
Application Archive
<javac
srcdir="src"
destdir="${build.dir}/WEB-INF/classes"
debug="${javac.debug}"
classpathref="compile.classpath"
/>
<jar basedir="${build.dir}"
jarfile="${name}.jar“
includes="**/*.class"/>
<war destfile="myapp.war"
webxml="${web.dir}/WEB-INF/web.xml">
<fileset dir="WebRoot"/>
<lib dir="${lib.dir}">
<exclude name="jdbc1.jar"/>
</lib>
<classes dir="${build.dir}/bin"/>
</war>
More Tasks…
• <java>
Executes Java
class
<echo message="Hello, world"/>
• <echo>
<echo message=“Line break:${line.separator}"/>
Prints a message
• <junit>
Runs
JUnit
tests
<java classname="test.Main">
<arg value="-h"/>
<classpath>
<pathelement location="dist/test.jar"/>
<pathelement path="${java.class.path}"/>
</classpath>
</java>
<echo level="error">
Fatal error!
</echo>
<junit>
<test name="my.test.TestCase"/>
</junit>
<junit printsummary="yes" fork="yes" haltonfailure="yes">
<formatter type="plain"/>
<test name="my.test.TestCase"/>
</junit>
References
• Ant Home
http://jakarta.apache.org/ant
• Ant Online Manual
http://ant.apache.org/manual/index.html
• Books on Ant
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Ant Developer's Handbook by Alan Williamson, Kirk Pepperdine, Joey
Gibson, Andrew Wu
Java™ Extreme Programming Cookbook by Eric M. Burke, Brian M.
Coyner
Java Development With Ant by Erik Hatcher, Steve Loughran
http://www.amazon.com/exec/obidos/ASIN/1930110588

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