All properties can also be set using Constant Configuration in an XML configuration file.

The framework uses a number of properties that can be changed to fit your needs. To change any of these properties, specify the property key and value in an struts.properties file. The properties file can be locate anywhere on the classpath, but it is typically found under /WEB-INF/classes

The list of properties can be found in struts-default.properties (inside struts2.jar).