Tagged distributions of the framework can be downloaded, or the latest version can obtained from the source code repository.

From a Distribution

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The latest distribution packages releases, including official beta versions are found on Java DevNet.

From CVS (The Bleeding Edge)

Short answer:

cvs -d :pserver:guest@cvs.dev.java.net:/cvs login
(Use an empty password, just hit enter..)
cvs -d :pserver:guest@cvs.dev.java.net:/cvs checkout opensymphony
cvs -d :pserver:guest@cvs.dev.java.net:/cvs checkout webwork

optional:
cvs -d :pserver:guest@cvs.dev.java.net:/cvs checkout xwork

Note: One needs to have ivy in $ANT_HOME/lib, cause WebWork uses ivy to manage its library dependencies.

beta releases, can be downloaded from the Apache Struts Project.

From the Repository

Use Subversion to checkout the source code.

> svn co https://svn.apache.org/repos/asf/struts/struts2/trunk/

Use Maven 2 to build a distribution.

> mvn install

For a detailed description, see Building the Framework from SourceLong answer:
See Building Webwork for a detailed description, including information on Ivy and JDK compatibility.