Introduction to Apache Ant

Introduction to Ant
@brownylin

Why

• Many IDEs have their own build
systems, so why is Ant important to
learn and use

• Answer:
‣ Eclipse may actually be using Ant
‣ Not just a build tool, must have for automation

What is Ant?

• Ant Java
Make Make
Java

Outline

•A First Ant Build
• Ant and Eclipse
• Ant programming

Prerequisite

Last login: Tue Aug 9 13:35:09 on ttys002
brownylins-MacBook:~ brownylin$ ant -version
Apache Ant(TM) version 1.8.2 compiled on June 3 2011
brownylins-MacBook:~ brownylin$ javac -version
javac 1.6.0_26
brownylins-MacBook:~ brownylin$ java -version
java version "1.6.0_26"
Java(TM) SE Runtime Environment (build 1.6.0_26-b03-383-11A511)
Java HotSpot(TM) 64-Bit Server VM (build 20.1-b02-383, mixed mode)
brownylins-MacBook:~ brownylin$

Main.java

package oata;

public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello World");
}
}

The Java Way
compile and run
md buildclasses
javac -sourcepath src -d buildclasses srcoataHelloWorld.java
java -cp buildclasses oata.HelloWorld

package
echo Main-Class: oata.HelloWorld>myManifest
md buildjar
jar cfm buildjarHelloWorld.jar myManifest -C buildclasses .
java -jar buildjarHelloWorld.jar

A Simple build.xml

<?xml version="1.0"?>
<project name="firstbuild" default="compile" >
<target name="compile">
<javac srcdir="." />
<echo>compilation complete!</echo>
</target>
</project>

Build

brownylins-MacBook:FirstBuild brownylin$ ant
Buildfile: /Users/brownylin/Desktop/AntPlay/FirstBuild/build.xml

compile:
[javac] Compiling 1 source file
[echo] compilation complete!

BUILD SUCCESSFUL
Total time: 0 seconds

Run

brownylins-MacBook:FirstBuild brownylin$ java Main a b .
a
b
.

Doing so shows the advantage of placing intermediate code into the build directory:
you can build a JAR file from it without having to list what files are included. This is
because all files in the directory tree should go in the JAR file, which, conveniently, is

Structure
the default behavior of the <jar> task.
With the destination directories defined, we’ve now completed the directory
structure of the project, which looks like the illustration in figure 2.2. When the build

Figure 2.2
The directory layout for our project—
keeping source separate from generated
files. The shaded directories and files are
created during the build.

<?xml version="1.0" ?>
<project name="structured" default="archive" >

<target name="init">
<mkdir dir="build/classes" />
<mkdir dir="dist" />
</target>

<target name="compile" depends="init" >
<javac srcdir="src" destdir="build/classes" />
</target>

<target name="archive" depends="compile" >
<jar destfile="dist/project.jar" basedir="build/
classes" />
</target>

<target name="clean" depends="init">
<delete dir="build" />
<delete dir="dist" />
</target>

</project>

Run

brownylins-MacBook:StructureBuild brownylin$ java -cp build/classes
org.antbook.welcome.Main a b .

a
b
.

Practice

• Tutorial: Hello World with Apache Ant

Outline

• A First Ant Build
•Ant and Eclipse
• Ant programming

Eclipse integrated with Ant

• Apache Ant 101: Make Java builds a
snap

• Make Ant easy with Eclipse

Outline

• A First Ant Build
• Ant and Eclipse
•Ant programming

Introduction

• Encapsulate each activity in the build
system into a high-level task

<target name="all">
<mkdir dir="pkg"/>
<jar basedir="obj" destfile="pkg/prog.jar"/>
<copy file="index.txt" tofile="pkg/index.txt"/>
</target>

Ant Programming

• Think Ant script as a sequence of build
tasks

• XML-based format, default naming
build.xml

• Each Ant’s XML file contains a project
• Each project contains one or more
targets that represent something the
user can build

An Example (1/2)
<project name="ant-project" default="all">

<property name="country" value="New Zealand"/>
<property name="city" value="Christchurch"/>

<target name="print-city">
<echo message="The nicest place in the world is"/>
<echo message="${city}, ${country}"/>
</target>

<target name="print-math">
<echo message="Two plus two equals four"/>
</target>

<target name="all" depends="print-city, print-math">
<echo message="Thank you!"/>
</target>

</project>

An Example (2/2)

• Result
$ ant
Buildfile: build.xml
print-city:
[echo] The nicest place in the world
is
[echo] Christchurch, New Zealand
print-math:
[echo] Two plus two equals four
all:
[echo] Thank you!
BUILD SUCCESSFUL
Total time: 218 milliseconds

Using Target (1/4)

• A target is a convenient way to group
tasks that need to be executed
sequentially

ant compile
ant jar
ant package
ant clean
ant javadoc

• The name of an Ant target isn’t
related to the name of any disk files

Using Target (2/4)

• Internal target
‣ Never invoked directly from the command line

<target name="java" depends="init, make-directories">

...

</target>

Using Target (3/4)

• Conditional
<property name="log-enabled" value="1"/>

<target name="append-to-log" if="log-enabled">
<echo message="Appending..."/>
</target>

• Direct execute target
<target name="java" depends="init, make-dir">
...
<antcall target="check-rules"/>
...
</target>

Using Target (4/4)

• across multiple build files
<target name="java" depends="init, make-dir">
...
<ant antfile=”utilities.xml” target="check"/>
...
</target>

• <antcall> performance suffers
• <import>
‣ Direct insertion
‣ Inherit a set of targets and override

Defining Properties (1/3)

• Defined by different ways
1. As a string
<property name="wife" value="Grace"/>
<property name="dog" value="Stan"/>
<property name="request"
value="${wife}, please take ${dog} for a walk"/>

2. As a ﬁle system location

<property name="obj-dir" location="obj/i386/debug"/>

${obj-dir} evaluates to
C:UsersPeterworkspaceAnt_Buildspropertiesobji386debug


3. Automatically set by the runtime environment
<echo>${os.name}</echo> // Windows Vista
<echo>${ant.file}</echo> // C:UsersPeterworkspaceAnt_Builds
propertiesbuild.xml
<echo>${user.name}</echo> // Peter

4. As the result of a <condition> task (is-
windows set true if system is windows)
<condition property="is-windows">
<contains string="${os.name}" substring="Windows"/>
</condition>


5. Deﬁned on the user’s command line (manually
specifying vs. hard-coding into the build.xml)

$ ant -Dname=Jones print-name

6. Loaded from an external properties ﬁle
(externalize a common set of properties)

<loadproperties srcfile="values.prop"/>

Properties Scope

• Available after defined (top-level or
inside a target)

• Can be defined only once in a given
project

• <ant> and <antcall> tasks
‣ Enable you to pass property values into the
newly invoked target (override any previous
deﬁnition only during the execution of that
target)

Built-In and Optional Tasks

• Basic file operations
• Archiving (.jar, .zip, etc...)
• The compilation of Java code
• The automatic generation of API
documentation

• Direct access to version-control tools
• Build lifecycle features (build version
numbers, sending email messages, and
playing sounds)

uses the B.class file without recompiling it. As a result, nothing that B.java
imports or extends is ever recompiled.

<javac> and <depend>
This algorithm works properly in many cases, but it causes incorrect builds in
other cases. (And this is where things get complex.) Imagine a case in which class
A imports class B, which then imports class C (see Figure 7.2). If both A.java
and C.java have been recently modified, the Java compiler is asked to recom-
pile both those files. When compiling class A, the compiler examines B.class
(because B is <depend srcdir="${src}" destdir="${obj}" /> with respect
imported by A), but because B.class is up-to-date
to B.java, it’s never recompiled. Class Adestdir="${obj}"/>
<javac srcdir="${src}" therefore uses the existing version of
class B.

imports imports
A.java B.java C.java

recompiles examines recompiles

A.class B.class C.class

Figure 7.2 The <javac> task doesn’t recompile B.java, even though C.java has
changed.

<chomd>, <copy>

• <chmod>
‣ Sets the access permissions on a ﬁle or
directory

• <copy>
‣ Similar to the Windows copy command and the
UNIX cp command

<fileset>, <patternset>,
<condtion>
• Selecting Multiple Files and Directories
<copy todir="pkg" flatten="true">
<fileset dir="src">
<include name="**/*.jpg"/>
<include name="**/*.png"/>
<exclude name="**/*flag*"/>
</fileset>

<fileset dir="lib">
<include name="**/*.gif"/>
<exclude name="**/*flag*"/>
</fileset>
</copy>

Extending Ant

• <exec>: enables you to invoke a shell command

• <java>: invoke an arbitrary collection of Java
code by specifying the class path and class
name

• <macrodef>: create a new type of task, with the
definition of that task written in Ant syntax

• <taskdef>: enables you to implement a task
using the full power of the Java language

• <script>: permits code from other scripting
languages to be directly embedded inside a
build.xml file (Javascript, Python and Ruby)

Introduction to Apache Ant

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