org.apache.struts.actions
public abstract class DispatchAction extends Action
An abstract Action that dispatches to a public
method that is named by the request parameter whose name is specified
by the parameter
property of the corresponding
ActionMapping. This Action is useful for developers who prefer to
combine many similar actions into a single Action class, in order to
simplify their application design.
To configure the use of this action in your
struts-config.xml
file, create an entry like this:
<action path="/saveSubscription"
type="org.apache.struts.actions.DispatchAction"
name="subscriptionForm"
scope="request"
input="/subscription.jsp"
parameter="method"/>
which will use the value of the request parameter named "method" to pick the appropriate "execute" method, which must have the same signature (other than method name) of the standard Action.execute method. For example, you might have the following three methods in the same action:
and call one of the methods with a URL like this:
http://localhost:8080/myapp/saveSubscription.do?method=update
NOTE - All of the other mapping characteristics of
this action must be shared by the various handlers. This places some
constraints over what types of handlers may reasonably be packaged into
the same DispatchAction
subclass.
NOTE - If the value of the request parameter is empty,
a method named unspecified
is called. The default action is
to throw an exception. If the request was cancelled (a html:cancel
button was pressed), the custom handler cancelled
will be used instead.
You can also override the getMethodName
method to override the action's
default handler selection.
Version: $Rev: 384089 $ $Date: 2006-03-08 01:50:52 +0000 (Wed, 08 Mar 2006) $
Field Summary | |
---|---|
protected Class | clazz
The Class instance of this DispatchAction class. |
protected static Log | log
Commons Logging instance. |
protected static MessageResources | messages
The message resources for this package. |
protected HashMap | methods
The set of Method objects we have introspected for this class,
keyed by method name. |
protected Class[] | types
The set of argument type classes for the reflected method call. |
Method Summary | |
---|---|
protected ActionForward | cancelled(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response)
Method which is dispatched to when the request is a cancel button submit.
|
protected ActionForward | dispatchMethod(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response, String name)
Dispatch to the specified method. |
ActionForward | execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response)
Process the specified HTTP request, and create the corresponding HTTP
response (or forward to another web component that will create it).
|
protected Method | getMethod(String name)
Introspect the current class to identify a method of the specified
name that accepts the same parameter types as the execute
method does.
|
protected String | getMethodName(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response, String parameter)
Returns the method name, given a parameter's value.
|
protected String | getParameter(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) Returns the parameter value. |
protected ActionForward | unspecified(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response)
Method which is dispatched to when there is no value for specified
request parameter included in the request. |
DispatchAction
class.DispatchAction
should override this method if
they wish to provide default behavior different than returning null.Since: Struts 1.2.0
Since: Struts 1.1
ActionForward
instance describing where and how
control should be forwarded, or null
if the response has
already been completed.
Parameters: mapping The ActionMapping used to select this instance form The optional ActionForm bean for this request (if any) request The HTTP request we are processing response The HTTP response we are creating
Throws: Exception if an exception occurs
execute
method does.
Parameters: name Name of the method to be introspected
Throws: NoSuchMethodException if no such method can be found
Parameters: mapping The ActionMapping used to select this instance form The optional ActionForm bean for this request (if any) request The HTTP request we are processing response The HTTP response we are creating parameter The ActionMapping
parameter's name
Returns: The method's name.
Since: Struts 1.2.0
Returns the parameter value.
Parameters: mapping The ActionMapping used to select this instance form The optional ActionForm bean for this request (if any) request The HTTP request we are processing response The HTTP response we are creating
Returns: The ActionMapping
parameter's value
Throws: Exception if the parameter is missing.
DispatchAction
should override this method if they wish
to provide default behavior different than throwing a ServletException.