• Introduction
• Download Java Development Kit (JDK) versions 6 and 7
• Install Apache Ant 1.8.2 or later
• Checkout or obtain the source code for Tomcat 7.0
• Configure download area
• Building Tomcat
• Building with Eclipse
• Building with other IDEs

Building Apache Tomcat from source is very easy, and is the first step to contributing to Tomcat. The complete and comprehensive instructions are provided in the file BUILDING.txt. The following is a quick step by step guide.

Building Apache Tomcat requires a Java 6 JDK to be installed and optionally a Java 7 JDK installed in parallel with Java 6 one. The Java 7 JDK is only required if you wish to build Tomcat with JSR-356 (Java WebSocket 1.1) support.

You can download JDKs from Oracle
http://www.oracle.com/technetwork/java/javase/downloads/index.html
or from another JDK vendor.

IMPORTANT: Set an environment variable JAVA_HOME to the pathname of the directory into which you installed the Java 6 JDK. The path to Java 7 JDK is configured in build.properties file (see below).

Download a binary distribution of Ant 1.8.2 or later from here.

Unpack the binary distribution into a convenient location so that the Ant release resides in its own directory (conventionally named apache-ant-1.8.x). For the remainder of this guide, the symbolic name ${ant.home} is used to refer to the full pathname of the Ant installation directory directory.

IMPORTANT: Create an ANT_HOME environment variable to point the directory ${ant.home}, and modify the PATH environment variable to include directory ${ant.home}/bin in its list. This makes the ant command line script available, which will be used to actually perform the build.

Tomcat 7.0 SVN repository URL: http://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk/

Tomcat source packages: http://tomcat.apache.org/download-70.cgi.

Checkout the source using SVN, selecting a tag for released version or trunk for the current development code, or download and unpack a source package. For the remainder of this guide, the symbolic name ${tomcat.source} is used to refer to the location where the source has been placed.

Building Tomcat involves downloading a number of libraries that it depends on. It is strongly recommended to configure download area for those libraries.

By default the build is configured to download dependencies into directory /usr/share/java. On a typical Linux or MacOX system, an ordinary user will not have access to write to this directory, and, even if you do, it is likely not appropriate for you to write there. On Windows this usually corresponds to the C:\usr\share\java directory, unless Cygwin is used.

The build is controlled by creating a ${tomcat.source}/build.properties file. It can be used to redefine any property that is present in build.properties.default and build.xml files. The build.properties file does not exist by default. You have to create it.

The download area is defined by property base.path. For example:

# ----- Default Base Path for Dependent Packages -----
# Replace this path with the directory path where
# dependencies binaries should be downloaded.
base.path=/home/me/some-place-to-download-to

Different versions of Tomcat are allowed to share the same download area.

Another example:

base.path=${user.dir}/../libraries-tomcat7.0

Users who access the Internet through a proxy must use the properties file to indicate to Ant the proxy configuration:

# ----- Proxy setup -----
proxy.host=proxy.domain
proxy.port=8080
proxy.use=on

If you have installed a Java 7 JDK and wish to build Tomcat with JSR-356 (Java WebSocket 1.1) support, set java.7.home property in file ${tomcat.source}/build.properties to the location of the Java 7 JDK installation.

An example, using 32-bit JDK on a 64-bit Windows system:

# Location of Java 7 JDK
java.7.home=C:/Program Files (x86)/Java/jdk1.7.0_72

Use the following commands to build Tomcat:

cd ${tomcat.source}
ant

Once the build has completed successfully, a usable Tomcat installation will have been produced in the ${tomcat.source}/output/build directory, and can be started and stopped with the usual scripts.

IMPORTANT: This is not a supported means of building Tomcat; this information is provided without warranty :-). The only supported means of building Tomcat is with the Ant build described above. However, some developers like to work on Java code with a Java IDE, and the following steps have been used by some developers.

NOTE: This will not let you build everything under Eclipse; the build process requires use of Ant for the many stages that aren't simple Java compilations. However, it will allow you to view and edit the Java code, get warnings, reformat code, perform refactorings, run Tomcat under the IDE, and so on.

WARNING: Do not forget to create and configure ${tomcat.source}/build.properties file as described above before running any Ant targets.

Sample Eclipse project files and launch targets are provided in the res/ide-support/eclipse directory of the source tree. The instructions below will automatically copy these into the required locations.

Two Ant targets are provided as a convenience. The first one, named ide-eclipse, downloads all binary dependencies and configures Eclipse project in the root of the source tree. The created Eclipse project targets a Java 6 JDK and skips WebSocket classes that cannot be compiled with Java 6.

The second target, named ide-eclipse-websocket, creates directory ../tomcat-7.0.x-java7 and configures the second Eclipse project there. This project targets a Java 7 JDK. This project does not have its own source tree, but accesses a subset of the source tree of the first project, compiling all WebSocket classes that were skipped.

cd ${tomcat.source}
ant ide-eclipse
ant ide-eclipse-websocket

Start Eclipse and create a new Workspace.

Open the Preferences dialog and then select Java->Build Path->Classpath Variables to add two new Classpath Variables:

TOMCAT_LIBS_BASE	The same location as the base.path setting in build.properties, where the binary dependencies have been downloaded
ANT_HOME	the base path of Ant 1.8.2 or later

In the Preferences dialog go to Java->Installed JREs and add JDK 6 and JDK 7 there. Close the dialog.

Use File->Import command from menu and choose Existing Projects into Workspace. From there choose the root directory of the Tomcat source tree (${tomcat.source}) and import the project located there. Import the second project as well, if you have created it (../tomcat-7.0.x-java7).

start-tomcat and stop-tomcat launch configurations are provided in res/ide-support/eclipse and will be available in the Run->Run Configurations dialog. Use these to start and stop Tomcat from Eclipse. If you want to configure these yourself (or are using a different IDE) then use org.apache.catalina.startup.Bootstrap as the main class, start/stop etc. as program arguments, and specify -Dcatalina.home=... (with the name of your build directory) as VM arguments.

Tweaking a few formatting preferences will make it much easier to keep consistent with Tomcat coding conventions (and have your contributions accepted):

Java -> Code Style -> Formatter -> Edit...	Tab policy: Spaces only Tab and Indentation size: 4
General -> Editors -> Text Editors	Displayed tab width: 2 Insert spaces for tabs Show whitespace characters (optional)
XML -> XML Files -> Editor	Indent using spaces Indentation size: 2
Ant -> Editor -> Formatter	Tab size: 2 Use tab character instead of spaces: unchecked

The recommended configuration of Compiler Warnings is documented in res/ide-support/eclipse/java-compiler-errors-warnings.txt file.

The same general approach should work for most IDEs; it has been reported to work in IntelliJ IDEA, for example.