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 or from the nightly snapshots . 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 1.6 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.
To make building Velocity easy and consistent, we require an Apache project called Ant version 1.6 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).
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
build.properties 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:
ant
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. They can be found here .
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.
The tests are run with the ant task <junit>.  For ant 1.6, this task requires that 
junit.jar be copied into the lib subdirectory of your 
ant directory.  For ant 1.7 this is not required.
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:
test:
    [mkdir] Created dir: ..../bin/test-reports
    [junit] Running org.apache.velocity.io.UnicodeInputStreamTestCase
    [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
...
BUILD SUCCESSFUL
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.