An Introduction to AntOverview • What is Ant? • Installing Ant • Anatomy of a build file – Projects – Properties – Targets – Tasks • Example build file • Running a build fileWhat is Ant? • Ant is a Java based tool for automating the build process • Similar to make but implemented using Java – Platform independent commands (works on Windows, Mac & Unix) • XML based format – Avoids the dreaded tab issue in make files • Easily extendable using Java classes • Ant is an open source (free) Apache projectAutomating the Build (C & make) • The goal is to automate the build process a.out: driver.o foo.o bar.o gcc driver.o foo.o bar.o driver.o: driver.c foo.h bar.h gcc -c driver.c foo.o: foo.c foo.h gcc -c foo.c bar.o: gcc -c bar.c linux3[1]% make gcc -c driver.c gcc -c foo.c gcc -c bar.c gcc driver.o foo.o bar.o linux3[2]% foo.c foo.h bar.h bar.c driver.c foo.o bar.o driver.o a.out gcc -c foo.c gcc -c bar.c gcc -c driver.c gcc driver.o foo.o bar.oInstalling Ant • Ant can be downloaded from… – http://ant.apache.org/ • Ant comes bundled as a zip file or a tarball • Simply unwrap the file to some directory where you want to store the executables – I typically unwrap the zip file into C:\Program Files, and rename to C:\Program Files\ant\ – This directory is known as ANT_HOMEAnt Setup • Set the ANT_HOME environment variable to where you installed Ant • Add the ANT_HOME/bin directory to your path • Set the JAVA_HOME environment variable to the location where you installed Java • Setting environment variables – Windows: right click My Computer Properties Advanced Environment Variables – UNIX: shell specific settingsProject Organization • The following example assumes that your workspace will be organized like so… build.xml Project Directory src *.java bin *.class doc *.htmlAnatomy of a Build File • Ant’s build files are written in XML – Convention is to call file build.xml • Each build file contains – A project – At least 1 target • Targets are composed of some number of tasks • Build files may also contain properties – Like macros in a make file • Comments are within <!-- --> blocksProjects • The project tag is used to define the project you wish to work with • Projects tags typically contain 3 attributes – name – a logical name for the project – default – the default target to execute – basedir – the base directory for which all operations are done relative to • Additionally, a description for the project can be specified from within the project tagBuild File <project name="Sample Project" default="compile" basedir="."> <description> A sample build file for this project </description> </project>Properties • Build files may contain constants (known as properties) to assign a value to a variable which can then be used throughout the project – Makes maintaining large build files more manageable • Projects can have a set of properties • Property tags consist of a name/value pair – Analogous to macros from makeBuild File with Properties <project name="Sample Project" default="compile" basedir="."> <description> A sample build file for this project </description> <!-- global properties for this build file --> <property name="source.dir" location="src"/> <property name="build.dir" location="bin"/> <property name="doc.dir" location="doc"/> </project>Targets • The target tag has the following required attribute – name – the logical name for a target • Targets may also have optional attributes such as – depends – a list of other target names for which this task is dependant upon, the specified task(s) get executed first – description – a description of what a target does • Like make files, targets in Ant can depend on some number of other targets – For example, we might have a target to create a jarfile, which first depends upon another target to compile the code • A build file may additionally specify a default targetBuild File with Targets <project name="Sample Project" default="compile" basedir="."> ... <!-- set up some directories used by this project --> <target name="init" description="setup project directories"> </target> <!-- Compile the java code in src dir into build dir --> <target name="compile" depends="init" description="compile java sources"> </target> <!-- Generate javadocs for current project into docs dir --> <target name="doc" depends="init" description="generate documentation"> </target> <!-- Delete the build & doc directories and Emacs backup (*~) files --> <target name="clean" description="tidy up the workspace"> </target> </project>Tasks • A task represents an action that needs execution • Tasks have a variable number of attributes which are task dependant • There are a number of build-in tasks, most of which are things which you would typically do as part of a build process – Create a directory – Compile java source code – Run the javadoc tool over some files – Create a jar file from a set of files – Remove files/directories – And many, many others… • For a full list see: http://ant.apache.org/manual/coretasklist.htmlInitialization Target & Tasks • Our initialization target creates the build and documentation directories – The mkdir task creates a directory <project name="Sample Project" default="compile" basedir="."> ... <!-- set up some directories used by this project --> <target name="init" description="setup project directories"> <mkdir dir="${build.dir}"/> <mkdir dir="${doc.dir}"/> </target> ... </project>Compilation Target & Tasks • Our compilation target will compile all java files in the source directory – The javac task compiles sources into classes – Note the dependence on the init task <project name="Sample Project" default="compile" basedir="."> ... <!-- Compile the java code in ${src.dir} into ${build.dir} --> <target name="compile" depends="init" description="compile java sources"> <javac srcdir="${source.dir}" destdir="${build.dir}"/> </target> ... </project>Javadoc Target & Tasks • Our documentation target will create the HTML documentation – The javadoc task
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