This is the second article on Apache ANT tutorials for beginners series As I have always said that I like the short, clear, and concise tutorial which tells about few concepts but in a clear and concise manner and puts weight on fundamentals. I try to adopt the same theory while writing my blog post while writing my experience coupled with the concept which is important for a software developer's point of view. Here I am answering some of the basic questions related to installing the ANT tool, running ANT build, creating a build.XML file, debugging build.xml in the case of any issue.
These questions have been asked by my students while teaching them JAVA and related technology in my early career.
How do I run ant?
To run you need to download ant and install it on your machine, then create environment variable ANT_HOME and include ANT_HOME/bin into your PATH like below.
In Windows path=%path%;%ANT_HOME%/bin
In Linux PATH =${PATH}:${ANT_Home}/bin
Now you can open a command prompt and type ant.
If you get this output, means ant binaries is not in your path
C:\Documents and Settings>ant
'ant' is not recognized as an internal or external command, operable program, or batch file.
Otherwise, you will get output that will complain about the build file if it doesn’t exist.
C:\Documents and Settings>ant
Buildfile: build.xml does not exist!
Build failed
How do I write build.xml file?
here is a sample build.xml you just need to know important element e.g. project ,target ,property and task and the order in which different target gets executed to start with basic build procedure.
<?xml version="1.0"?>
<project name="test" default="all" basedir=".">
<property name="src" value="src"/>
<property name="build" value="build"/>
<property name="lib" value="lib"/>
<target name="all" depends="clean, compile" description="Builds the whole project">
<echo>Doing all</echo>
</target>
<target name="Clean" description="Removes previous build">
<delete verbose="true">
<fileset dir="${build}"/>
</delete>
</target>
<target name="compile" depends="clean" description="compile whole project">
<echo>compile ${ant.project.name} </echo>
<copy file="${src}/splashscreen.jpeg" tofile="${build}/splashscreen.jpeg"/>
<javac srcdir="${src}" destdir="${build}" includes="Test.java"/>
</target>
</project>
lets see what we are doing here :
<project name="test" default="all" basedir=".">
This line defines our project; every build file must have this line. The project name is “test” defined by attribute “name”; default target is “all” while running “ant” command from command prompt if we don’t specify any target than ant executed this default target.
basedir tells which is the top level directory for creating the build in this case its current directory (from where you run ant command) , denoted by dot “.” .
<property name="src" value="src"/>
Here we are declaring and specifying property ,you can say variable every property has at least two attributes “name” and “value” , though you can define your all properties in a separate properties file and load from there as well .<property> denotes ant’s property task, which do have some other attribute e.g. location to specify location of any properties file. I recommend that you always use property in your build.xml instead of using hard coded values in target for directory name etc , this will give you flexibility to change the value anytime without changing at many places (in case you have hard coded it).
<target name="all" depends="clean, compile" description="Builds the whole project">
Here we are defining a target since we have already called target “all” as default in project tag, so if we don’t specify this target our build will fail to say “target not found”.
”name” attribute specified name of target. “depends ontarget” says that before executing this target executed first “clean” and then “compile”
<echo>Doing all</echo>
This will print message in console as “doing all”
<target name="Clean" description="Removes previous build">
This is target “Clean” which will delete old build before building new one , you can have as many target you want based on your need.
<delete verbose="true">
<fileset dir="${build}"/>
</delete>
delete task or tag is used to delete directory, file etc, verbose=true makes it to print message while deleting in cosole, <fileset> is an important tag and I recommend you to read in detail somewhere in ant manual or may be I will explain in detail sometime because it include “patternset” which supports pattern matching of directory/files via its includes and excludes attribute which is extremely useful to filter unwanted files (generally meta data files form CVS, SVN etc).
Here we are deleting build directory by using value of property “build”, ${build} denotes value of any property.
<target name="compile" depends="clean" description="compile whole project">
<echo>compile ${ant.project.name} </echo>
<copy file="${src}/splashscreen.jpeg" tofile="${build}/splashscreen.jpeg"/>
<javac srcdir="${src}" destdir="${build}" includes="Test.java"/>
</target>
</project>
This is our compile target ,which compiles our code and also copies resources e.g. images, we can also create jar file using ant, which we are not doing here just for simplicity.
Imporant thing here is property ${ant.project.name} this is builtin propety provided by ant and its’s value is name of project defined by attribute “name” of proejct tag.
<copy> tag is used to copy files and <javac> tag is used to compile java code .
How do I debug build.xml?
if you see the problem on your build or you are getting exceptions related to finding files/directory or anything then you would like to know what’s going behind there are two option , run ant on the verbose option, it will print lots of detail (I don’t prefer this) because of so much unwanted information but can be useful in certain situation.
Second and my preferred way is the good old “echo” way. use echo task to print values of properties, variables or printing simple messages to check the work flow.
here are some examples of using echo
<echo>Doing all</echo>
<echo message="Now creating directory source "/>
<echo level="warning" message ="Active configuration (config.active property) is not set - using default." />
How do I enforce ant to use file other than build.xml?
Normally when you run ant from any directory from command prompt it will look for file called build.xml in current directory; if it doesn’t find the file it will give error. If you have file named “custom_build.xml” you can instruct ant to use this file for building your application by using option “-f” e.g. ant –f custom_build.xml
Hope this would be useful let me know if you have any questions, doubt etc will be happy to answer.
C:\Documents and Settings>ant
Buildfile: build.xml does not exist!
Build failed
How do I write build.xml file?
here is a sample build.xml you just need to know important element e.g. project ,target ,property and task and the order in which different target gets executed to start with basic build procedure.<?xml version="1.0"?>
<project name="test" default="all" basedir=".">
<property name="src" value="src"/>
<property name="build" value="build"/>
<property name="lib" value="lib"/>
<target name="all" depends="clean, compile" description="Builds the whole project">
<echo>Doing all</echo>
</target>
<target name="Clean" description="Removes previous build">
<delete verbose="true">
<fileset dir="${build}"/>
</delete>
</target>
<target name="compile" depends="clean" description="compile whole project">
<echo>compile ${ant.project.name} </echo>
<copy file="${src}/splashscreen.jpeg" tofile="${build}/splashscreen.jpeg"/>
<javac srcdir="${src}" destdir="${build}" includes="Test.java"/>
</target>
</project>
lets see what we are doing here :
<project name="test" default="all" basedir=".">
This line defines our project; every build file must have this line. The project name is “test” defined by attribute “name”; default target is “all” while running “ant” command from command prompt if we don’t specify any target than ant executed this default target.
basedir tells which is the top level directory for creating the build in this case its current directory (from where you run ant command) , denoted by dot “.” .
<property name="src" value="src"/>
Here we are declaring and specifying property ,you can say variable every property has at least two attributes “name” and “value” , though you can define your all properties in a separate properties file and load from there as well .<property> denotes ant’s property task, which do have some other attribute e.g. location to specify location of any properties file. I recommend that you always use property in your build.xml instead of using hard coded values in target for directory name etc , this will give you flexibility to change the value anytime without changing at many places (in case you have hard coded it).
<target name="all" depends="clean, compile" description="Builds the whole project">
Here we are defining a target since we have already called target “all” as default in project tag, so if we don’t specify this target our build will fail to say “target not found”.
”name” attribute specified name of target. “depends ontarget” says that before executing this target executed first “clean” and then “compile”
<echo>Doing all</echo>
This will print message in console as “doing all”
<target name="Clean" description="Removes previous build">
This is target “Clean” which will delete old build before building new one , you can have as many target you want based on your need.
<delete verbose="true">
<fileset dir="${build}"/>
</delete>
delete task or tag is used to delete directory, file etc, verbose=true makes it to print message while deleting in cosole, <fileset> is an important tag and I recommend you to read in detail somewhere in ant manual or may be I will explain in detail sometime because it include “patternset” which supports pattern matching of directory/files via its includes and excludes attribute which is extremely useful to filter unwanted files (generally meta data files form CVS, SVN etc).
Here we are deleting build directory by using value of property “build”, ${build} denotes value of any property.
<target name="compile" depends="clean" description="compile whole project">
<echo>compile ${ant.project.name} </echo>
<copy file="${src}/splashscreen.jpeg" tofile="${build}/splashscreen.jpeg"/>
<javac srcdir="${src}" destdir="${build}" includes="Test.java"/>
</target>
</project>
This is our compile target ,which compiles our code and also copies resources e.g. images, we can also create jar file using ant, which we are not doing here just for simplicity.
Imporant thing here is property ${ant.project.name} this is builtin propety provided by ant and its’s value is name of project defined by attribute “name” of proejct tag.
<copy> tag is used to copy files and <javac> tag is used to compile java code .
How do I debug build.xml?
if you see the problem on your build or you are getting exceptions related to finding files/directory or anything then you would like to know what’s going behind there are two option , run ant on the verbose option, it will print lots of detail (I don’t prefer this) because of so much unwanted information but can be useful in certain situation.
Second and my preferred way is the good old “echo” way. use echo task to print values of properties, variables or printing simple messages to check the work flow.
here are some examples of using echo
<echo>Doing all</echo>
<echo message="Now creating directory source "/>
<echo level="warning" message ="Active configuration (config.active property) is not set - using default." />
How do I enforce ant to use file other than build.xml?
Normally when you run ant from any directory from command prompt it will look for file called build.xml in current directory; if it doesn’t find the file it will give error. If you have file named “custom_build.xml” you can instruct ant to use this file for building your application by using option “-f” e.g. ant –f custom_build.xml
Hope this would be useful let me know if you have any questions, doubt etc will be happy to answer.
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