Apache Ant is a software tool for automating software build processes which originated from the Apache Tomcat project in early 2000. It was a replacement for the Make build tool of Unix, and was created due to a number of problems with Unix's make. It is similar to Make but is implemented using the Java language, requires the Java platform, and is best suited to building Java projects.
The most immediately noticeable difference between Ant and Make is that Ant uses XML to describe the code build process and its dependencies, whereas Make uses the Makefile format.
By default, the XML file is named
Released under an Apache License by the Apache Software Foundation, Ant is an open-source project.
Ant "Another Neat Tool" was conceived by James Duncan Davidson while preparing Sun Microsystems's reference JSP and Servlet engine, later Apache Tomcat, for release as open-source. A proprietary version of Make was used to build it on the Solaris platform, but in the open-source world, there was no way of controlling which platform was used to build Tomcat; so Ant was created as a simple platform-independent tool to build Tomcat from directives in an XML "build file". Ant version 1.1 was officially released as a stand-alone product on July 19, 2000.
Several proposals for an Ant version 2 have been made, such as AntEater by James Duncan Davidson, Myrmidon by Peter Donald and Mutant by Conor MacNeill, none of which were able to find large acceptance with the developer community.
At one time 2002, Ant was the build tool used by most Java development projects. For example, most open source Java developers included
build.xml files with their distribution. Because Ant made it trivial to integrate JUnit tests with the build process, Ant made it easy for willing developers to adopt test-driven development, and even extreme programming.
WOProject-Ant is just one of many examples of a task extension written for Ant. These extensions are installed by copying their
.jar files into ant's
lib directory. Once this is done, these task extensions can be invoked directly in the typical
build.xml file. The WOProject extensions allow WebObjects developers to use ant in building their frameworks and apps, instead of using Apple's Xcode suite.
Antcontrib provides a collection of tasks such as conditional statements and operations on properties as well as other useful tasks.
Ant-contrib.unkrig.de implements tasks and types for networking, Swing user interfaces, JSON processing and other.
Other task extensions exist for Perforce, .NET Framework, EJB, and filesystem manipulations.
Below is listed a sample
build.xml file for a simple Java "Hello, world" application. It defines four targets -
jar , each of which has an associated description. The
jar target lists the
compile target as a dependency. This tells Ant that before it can start the
jar target it must first complete the
<?xml version="1.0"?> <project name="Hello" default="compile"> <target name="clean" description="remove intermediate files"> <delete dir="classes"/> </target> <target name="clobber" depends="clean" description="remove all artifact files"> <delete file="hello.jar"/> </target> <target name="compile" description="compile the Java source code to class files"> <mkdir dir="classes"/> <javac srcdir="." destdir="classes"/> </target> <target name="jar" depends="compile" description="create a Jar file for the application"> <jar destfile="hello.jar"> <fileset dir="classes" includes="**/*.class"/> <manifest> <attribute name="Main-Class" value="HelloProgram"/> </manifest> </jar> </target> </project>
Within each target are the actions that Ant must take to build that target; these are performed using built-in tasks. For example, to build the
compile target Ant must first create a directory called
classes which Ant will do only if it does not already exist and then invoke the Java compiler. Therefore, the tasks used are
javac. These perform a similar task to the command-line utilities of the same name.
Another task used in this example is named
This Ant task has the same name as the common Java command-line utility, JAR, but is really a call to the Ant program's built-in JAR/ZIP file support. This detail is not relevant to most end users, who just get the JAR they wanted, with the files they asked for.
Many Ant tasks delegate their work to external programs, either native or Java. They use Ant's own
<java> tasks to set up the command lines, and handle all the details of mapping from information in the build file to the program's arguments and interpreting the return value. Users can see which tasks do this e.g.
<rpm>, by trying to execute the task on a system without the underlying program on the path, or without a full Java Development Kit JDK installed.
One of the primary aims of Ant was to solve Make's portability problems. The first portability issue in a Makefile is that the actions required to create a target are specified as shell commands which are specific to the platform on which Make runs. Different platforms require different shell commands. Ant solves this problem by providing a large amount of built-in functionality that is designed to behave the same on all platforms. For example, in the sample
build.xml file above, the clean target deletes the
classes directory and everything in it. In a Makefile this would typically be done with the command:
rm -rf classes/
is a Unix-specific command unavailable in some other environments. Microsoft Windows, for example, would use:
rmdir /S /Q classes
In an Ant build file the same goal would be accomplished using a built-in command:
A second portability issue is a result of the fact that the symbol used to delimit elements of file system directory path components differs from one platform to another. Unix uses a forward slash / to delimit components whereas Windows uses a backslash \. Ant build files let authors choose their favorite convention: forward slash or backslash for directories; semicolon or colon for path separators. It converts each to the symbol appropriate to the platform on which it executes.
There exist myriad third-party Ant extensions called antlibs that provide much of the missing functionality. Also, the Eclipse integrated development environment IDE can build and execute Ant scripts, while the NetBeans IDE uses Ant for its internal build system. As both these IDEs are very popular development platforms, they can simplify Ant use significantly. As a bonus, Ant scripts generated by NetBeans can be used outside that IDE as standalone scripts.