9.5. Reporting Errors and Messages from an Action
Problem
You want to display error messages to the user when things go wrong and success messages when things go right.
Solution
For Struts 1.1, use ActionErrors for reporting
errors and ActionMessages for informational
messages. For Struts 1.2, use ActionMessages for
informational messages and errors.
Discussion
Struts gives you a least four classes and three custom tags for
creating, storing, and displaying errors and messages. In Struts 1.1,
the ActionErrors class is used to hold a
collection of errors, represented by ActionError
instances. Each ActionError consists of a key to
be looked up from the default MessageResources
bundle and an optional set of Objects (up to four)
to be used as parameters for message substitution. The
Action class in Example 9-9 shows
typical usage of ActionErrors.
Example 9-9. Creating ActionErrors from an Action
package com.oreilly.strutsckbk.ch09; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.commons.beanutils.PropertyUtils; import org.apache.struts.Globals; import org.apache.struts.action.Action; import org.apache.struts.action.ActionError; import org.apache.struts.action.ActionErrors; import org.apache.struts.action.ActionForm; import org.apache.struts.action.ActionForward; import org.apache.struts.action.ActionMapping; public class RegistrationAction extends Action { public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest ...