Modern IDEs provide excellent support for debugging. In addition, the framework provides support for inspecting framework-specific objects at runtime.

The Debugging Interceptor provides three debugging modes to provide insight into the data behind the page. The xml mode formats relevant framework objects as an XML document. The console mode provides a OGNL command line that accepts entry of runtime expressions, and the browser mode adds an interactive page that display objects from the Value Stack.

To use the debugging, first be sure that struts.devMode is set to true is enabled through the file or struts.xml file, like:

<constant name="struts.devMode" value="true" />

Then, whenever a page needs debugging, add ?debug=xml or ?debug=console or ?debug=browser to the URL.

- <debug>
  <parameters /> 
- <context>
- <struts.actionMapping>
  <class>class org.apache.struts2.dispatcher.mapper.ActionMapping</class> 
  <attr /> 
  <request /> 
  <session /> 
- <valueStack>
- <value>
  <actionErrors /> 
  <actionMessages /> 
  <class>class com.opensymphony.xwork2.ActionSupport</class> 
  <errorMessages /> 
  <errors /> 
  <fieldErrors /> 
- <locale>
  <class>class java.util.Locale</class> 
  <displayCountry>United States</displayCountry> 
  <displayName>English (United States)</displayName> 
  <displayVariant /> 
  <variant /> 
- <value>
  <class>class com.opensymphony.xwork2.DefaultTextProvider</class> 

For ?debug=xml use Internet Explorer or an IE tab in FireFox

For ?debug=console you may need to relax any popup blockers

Next: Development Mode

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  1. Spelling error. "mode" should be changed to "modes".

  2. devmode = true
    should be
    struts.devMode = true