Velocity Engine




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Velocity runs on a variety of platforms that have installed the Java 2 Virtual Machine. The J2SDK is required for users who want to compile Velocity from its source code.

Everything required to build Velocity comes with the distribution, which can be obtained from Subversion. However, you will need to install Ant to build the Velocity sources.

Ant is also an Apache project, and can be found here. To build Apache Velocity, you need at least Version 1.7 of Apache Ant.

The directory tree of the distribution looks like:

build/      This is where the build scripts live.
convert/    The WebMacro to Apache Velocity conversion program.
docs/       Velocity Documentation in HTML format.
docs/api/   Velocity Javadocs.
examples/   Examples how to use Velocity.
lib/        Dependencies for building and using Velocity.
lib/test/   Dependencies needed for the various unit tests.
src/        This is where all of the source code is located.
test/       Contains test files needed for the unit tests.
xdocs/      Here are the .xml files for building the .html files
            related to the website and documentation. The files
            located in docs/ have been built from these sources.

Required Tools

To make building Velocity easy and consistent, we require an Apache project called Ant version 1.7 or higher to perform the build process. We assume that you have followed Ant's installation instructions and have it properly installed.

Velocity requires JDK 1.4 or greater to compile. It's possible to use JDK 1.3 to compile but several useful features will not be included. Velocity requires a minimum of JDK 1.3 to run.

Finally, if you wish to modify Velocity's grammar you will need to a tool called JavaCC. We recommend version 3.2 or greater (for compatibility with JDK 1.5 syntax changes).

Jar Dependencies

Velocity requires various third party jar files for compiling and for running. Not all jar files are required in all cases. When building, all dependencies will be downloaded automatically. You can control the download with the skip.jar.loading and force.jar.loading properties in the file.

Jar Purpose Required at Runtime?
antlr-2.7.5.jar XML parsing (XPath queries in particular) Only for Anakia
avalon-logkit-2.1.jar Possible means of logging No
commons-collection-3.1.jar Used in parsing configuration Yes
commons-lang-2.1.jar Various String utility functions Yes
commons-logging-1.1.jar To redirect log output to commons-logging Only for those using commons-logging
jdom-1.0.jar XML parsing Only for Anakia
log4j.1.2.12.jar Possible means of logging No
oro-2.0.8.jar For regular expression parsing in tests and event handlers Only for reference escaping event handlers
servletapi-2.3.jar For the deprecated VelocityServlet and redirecting log output to the servlet log. Only for VelocityServlet or ServletLogChute
werken-xpath-0.9.4.jar XML parsing Only for Anakia
junit-3.8.1.jar For running unit tests No
hsqldb-1.7.1.jar For running database related unit tests No
ant.jar Required for compilation. Provided by the ant build tool. No

Note that you can always create a jar with all required run-time dependencies by executing the jar-dep task.


In each case below, it is assumed that you were successful in getting the distribution from Subversion or as a nightly build, and with the latter, were successful in unpacking. Also, it is assumed that you are starting in the 'velocity' directory, the root of the distribution tree. All directory references will be relative to 'velocity'.

Change to the build directory (cd build). Then, to build the jar file, simply type:


Executing this script will create a bin directory within the Velocity distribution directory. The bin directory will contain the compiled class files (inside a classes directory) as well as a velocity-XX.jar file, where XX is the current version number. Be sure to update your classpath to include Velocity's .jar file.

Note that to build any of the specific build targets simply add the target name to the command line. For example, to build the Javadoc API documentation:

ant javadocs

Some of the most useful targets are:

  • jar builds the complete Velocity jar in the bin directory. This jar will be called 'velocity-X.jar', where 'X' is the current version number. This jar does not include necessary dependencies for Velocity. If you use this target, you must put the required dependent jars in your CLASSPATH (or WEB-INF/lib). For convenience, you can use the jar-dep target to build a jar with all required dependent classes included.
  • jar-dep builds the complete Velocity jar in the bin directory.
  • clean deletes all generated classes, jars, documentation, and other files.
  • real-clean like clean but also deletes all downloaded jars.
  • docs builds these docs in the docs directory using Velocity's Anakia XML transformation tool. Allows you to use Velocity templates in place of stylesheets - give it a try!
  • examples builds the example code in the example programs found in the examples directory.
  • jar-src bundles all the Velocity source code into a single jar, placed in the bin directory.
  • javadocs builds the Javadoc class documentation in the docs/api directory
  • package will generate the complete Velocity distribution package.
  • parser will compile the JavaCC parser files from src/Parser.jjt into the appropriate Java source files. Requires JavaCC 3.2+ to be installed, and the property javacc.home to contain a path to the installed JavaCC directory.
  • test (after jar) will test Velocity against its testbed suite of test routines.

Velocity should build 'out of the box', independent of your classpath. If you get an error building Velocity, try a different nightly build (as sometimes we make a mistake and the Subversion at the time of the nightly snapshot isn't complete) or refresh from Subversion (you might have gotten a Subversion snapshot while a developer was checking things in.)

If the problems persist, do not hesitate to ask the Velocity community via our mail lists.

The Velocity developers use an automated test facility, and it is included in the distribution. You can use it to make sure that all is well with your build of Velocity.

To run the test suite, simply use the build target test when you build:

ant test

If all is well, you should see output similar to:

    [mkdir] Created dir: ..../bin/test-reports
    [junit] Running
    [junit] Tests run: 8, Failures: 0, Errors: 0, Time elapsed: 0.011 sec
    [junit] Running org.apache.velocity.test.AbsoluteFileResourceLoaderTestCase
    [junit] Tests run: 1, Failures: 0, Errors: 0, Time elapsed: 0.015 sec
    [junit] Running org.apache.velocity.test.ArithmeticTestCase
    [junit] Tests run: 7, Failures: 0, Errors: 0, Time elapsed: 0.006 sec
    [junit] Running org.apache.velocity.test.BuiltInEventHandlerTestCase


Total time: 42 seconds

Note that the number of tests may vary from those shown above, but if you see 'OK' after the tests are run, all is well.