Apache
Ant ( Another Neat Tool ) : Lesson 01
Apache
Ant is a Java based build tool from
Apache Software Foundation.
Ant's
build files are written in XML.
Why
do you need a build tool?
To
automate the build and deployment we need a build tool. It is do the
followings:
-
Compile code
-
Package the binaries
-
Deploy the binaries to the test server
-
Test your changes
-
Copy code from one location to another
Therefore,
Apache Ant is a build
and deployment tool that can be
executed from a command line.
Features
of Apache Ant -
*
Ant is the most complete Java build and deployment tool available.
*
Ant scripts are written using plain XML.
*
Ant is good at automating complicated repetitive tasks.
*
Ant comes with a big list of predefined tasks.
*
Ant provides an interface to develop custom tasks.
*
Ant can be easily invoked from the command line and it can integrate
with free and commercial IDEs.
Installing
Apache Ant -
Apache
Ant is distributed under the Apache Software License, a fully-fledged
open source license certified by the open source initiative.
1.
Ensure that the JAVA_HOME environment variable is set to the folder
where your JDK is installed.
2.
Download the binaries from http://ant.apache.org
3.
Unzip the zip file to a convenient location. (ex:- /usr/share/ )
4.
Create a new environment variable called ANT_HOME
that points to the Ant installation folder, in this case
"/usr/share/ant".
5.
Append the path to the Apache Ant batch file to the PATH environment
variable.
To
create the ANT_HOME, use followings :
- type command /$ sudo gedit /etc/environment
- Paste ANT_HOME="/usr/share/ant"
- Append to the PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:$JAVA_HOME:$JRE_HOME:$ANT_HOME"
6.
Verify the installation, use below commands and should see an output
similar to:
sanjeeva@sanjeeva:/$
ant -version
Apache
Ant(TM) version 1.8.2 compiled on December 3 2011
sanjeeva@sanjeeva:/$
$ANT_HOME
bash:
/usr/share/ant: Is a directory
Build
Files -
Ant's
build file, build.xml should live in the project's base
directory.
Although
you are free to use other file names or place the build file in some
other location.
All
build files require the project element and at least one
target element.
project
element has three attributes :
name :
The Name of the project. (Optional)
default :
The default target for the build
script. A project may contain any number of targets. This
attribute specifies which target
should be considered as the default.
(Mandatory)
basedir:
The base directory (or) the root
folder for the project. (Optional)
target
is a collection of tasks that you want
to run as one unit.
Below
example, we have a simple target to provide an informational message
to the user.
<?xml
version="1.0"?>
<project
name="Hello
World Project" default="info">
<target
name="info">
<echo>Hello
World - Welcome to Apache Ant!</echo>
</target>
</project>
*
Targets can have dependencies on other targets.
For
example,
a
deploy target may have a dependency on the package target,
the
package target may have a dependency on the compile target and so
forth.
Dependencies
are denoted using the depends
attribute.
For
example:
<target
name="deploy"
depends="pacakge">
....
</target>
<target
name="pacakge"
depends="clean,compile">
....
</target>
<target
name="clean"
>
....
</target>
<target
name="compile"
>
....
</target>
The
target element has the following attributes:
name :
The name of the target (Required)
depends
: Comma separated list of all
targets that this target depends on. (Optional)
description
: A short description of the
target. (optional)
if
: Allows the execution of a target
based on the trueness of a conditional attribute. (optional)
unless
: Adds the target to the
dependency list of the specified Extension Point.
An
Extension Point is similar to a target, but it does not have any
tasks. (Optional)
Run
a build file :
1.
Save the below as build.xml.
<?xml
version="1.0"?>
<project
name="Hello
World Project" default="info">
<target
name="info">
<echo>Hello
World - Welcome to Apache Ant!</echo>
</target>
</project>
2.
Open a terminal and navigate to the folder where the build.xml
resides.
3.
Type ant info Or ant and
see the output.
sanjeeva@sanjeeva:~$
ant
Buildfile:
/home/sanjeeva/build.xml
info:
[echo]
Hello World - Welcome to Apache Ant!
BUILD
SUCCESSFUL
Total
time: 0 seconds
Property
element
Ant
uses the property element which allows you to specify properties.
This
allows the properties to be changed from one build to another. or
from one environment to another.
By
default, Ant provides the following pre-defined properties that can
be used in the build file;
ant.file
: The full location of the build
file.
ant.version
: The version of the Apache Ant
installation.
basedir
: The basedir of the build, as
specified in the basedir attribute of the project element.
ant.java.version
: The version of the JDK that is
used by Ant.
ant.project.name
: The name of the project, as
specified in the name atrribute of the project element
ant.project.default-target
: The default target of the current
project
ant.project.invoked-targets
: Comma separated list of the
targets that were invoked in the current project
ant.core.lib
: The full location of the ant jar
file
ant.home
: The home directory of Ant
installation
ant.library.dir
: The home directory for Ant
library files - typically ANT_HOME/lib folder.
In
addition to the above, the user can define additional properties
using the property
element.
Example
: shows how to define a property called “devname”:
<?xml
version="1.0"?>
<project
name="Hello
World Project" default="info">
<property
name="devname"
value="Sanjeeva
Pathirana"/>
<target
name="info">
<echo>Apache
Ant version is ${ant.version} </echo>
<echo>Developer
is ${devname} </echo>
</target>
</project>
[
Out put ] :
Buildfile:
/home/sanjeeva/build.xml
info:
[echo]
Apache Ant version is Apache Ant(TM) version 1.8.2 compiled on
December 3 2011
[echo]
Developer is Sanjeeva Pathirana
Ant
Property files -
Storing
the properties in a separate file allows you to reuse the same build
file, with different property settings for different execution
environment. For example, build properties file can be maintained
separately for DEV, TEST and PROD environments.
The
property file is named build.properties
and is placed along side the build.xml file.
You
could create multiple build properties file based on the deployment
environments - such as build.properties.dev and build.properties.test
Example
: shows the build.xml and an associated build.properties file
<?xml
version="1.0"?>
<project
name="Hello
World Project" default="info">
<property
file="build.properties"/>
<target
name="info">
<echo>Apache
Ant version is ${ant.version} </echo>
<echo>Developer
is ${devname}
</echo>
<echo>Build
Version is ${buildversion}
</echo>
</target>
</project>
build.properties
#
The Site Name
devname=Sanjeeva
Pathirana
buildversion=3.3.2
Output
-
Buildfile:
/home/sanjeeva/build.xml
info:
[echo]
Apache Ant version is Apache Ant(TM) version 1.8.2 compiled on
December 3 2011
[echo]
Developer is Sanjeeva Pathirana
[echo]
Build Version is 3.3.2
BUILD
SUCCESSFUL
Total time: 0
seconds
