org.beyondcode.struts.dispatcher
Class MethodDispatcherAction

java.lang.Object
  |
  +--org.apache.struts.action.Action
        |
        +--org.beyondcode.struts.dispatcher.MethodDispatcherAction

public abstract class MethodDispatcherAction

extends org.apache.struts.action.Action

This class dispatches incoming requests to one of its member functions according to the value of the method property of the mapping supplied with the request.

This class is meant to be extended by custom classes, which provide the member functions which are targets of request dispatches. Member functions that requests can be dispatched to need to have exactly the same signature (return type and arguments) as the perform() method in org.apache.struts.action.Action.

Request dispatching to member functions is access controlled. Dispatching occurs only when the request has access to the target function (as determined by hasAccess()) - otherwise the request is forwarded to the denied forward. The hasAccess() method should be overriden in subclasses to implement custom access control, based on information contained in the request (such as cookies or the HttpSession) and the mapping.

The mapping supplied with the request needs to implement the org.beyondcode.struts.dispatcher.DispatcherMapping interface, to provide access to the necessary properties.

Author:

Philipp K. Janert

Field Summary

protected static org.apache.struts.util.MessageResources	messages Handle to properties file with error messages.
protected java.util.HashMap	methods Handles to methods that have been recognized by introspection as possible targets for dispatches.

Fields inherited from class org.apache.struts.action.Action

DATA_SOURCE_KEY, defaultLocale, ERROR_KEY, EXCEPTION_KEY, FORM_BEANS_KEY, FORWARDS_KEY, LOCALE_KEY, MAPPING_KEY, MAPPINGS_KEY, MESSAGES_KEY, MULTIPART_KEY, servlet, SERVLET_KEY, TRANSACTION_TOKEN_KEY

Constructor Summary

protected

MethodDispatcherAction() Default constructor.

Method Summary

protected boolean	hasAccess(DispatcherMapping mapping, javax.servlet.http.HttpServletRequest request) This method should be overridden in subclasses to implement custom access control to individual methods.
org.apache.struts.action.ActionForward	perform(org.apache.struts.action.ActionMapping mapping, org.apache.struts.action.ActionForm form, javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) When called by the ActionServlet, this method dispatches incoming requests to one of the methods recognized in the constructor, having the same signature as the perform() method.

Methods inherited from class org.apache.struts.action.Action

generateToken, getLocale, getResources, getServlet, isCancelled, isTokenValid, perform, perform, perform, resetToken, saveErrors, saveToken, setLocale, setServlet, toHex

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

messages

protected static org.apache.struts.util.MessageResources messages

Handle to properties file with error messages.

methods

protected java.util.HashMap methods

Handles to methods that have been recognized by introspection as possible targets for dispatches.

Constructor Detail

MethodDispatcherAction

protected MethodDispatcherAction()

Default constructor. Introspects the class and determines all public functions having whose full signature (arguments and returnType) corresponds to the signature of the perform() method. When comparing types of arguments and returnType, subclasses of the types used in the original perform() method are not permitted.

Method Detail

perform

public org.apache.struts.action.ActionForward perform(org.apache.struts.action.ActionMapping mapping,
                                                      org.apache.struts.action.ActionForm form,
                                                      javax.servlet.http.HttpServletRequest request,
                                                      javax.servlet.http.HttpServletResponse response)
                                               throws java.io.IOException,
                                                      javax.servlet.ServletException

When called by the ActionServlet, this method dispatches incoming requests to one of the methods recognized in the constructor, having the same signature as the perform() method. The name of the method to dispatch to is the value of the method property of the mapping argument, which must implement the DispatcherMapping interface.

This method also performs access control. Dispatch to the method named in the mapping only occurs if this class' hasAccess() method returns true, otherwise the value of mapping.denied() is returned from this method.

Overrides:

perform in class org.apache.struts.action.Action

Parameters:

mapping - Must implement DispatcherMapping

form -

request -

response -

Returns:

Selected forward, or null on error.

java.io.IOException

javax.servlet.ServletException

hasAccess

protected boolean hasAccess(DispatcherMapping mapping,
                            javax.servlet.http.HttpServletRequest request)

This method should be overridden in subclasses to implement custom access control to individual methods. Default implementation always returns true.

Parameters:

mapping - The mapping

request - The request

Returns:

true if this request has access to this action, false otherwise. The default implementation always returns true.