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java.lang.Objectorg.apache.struts.action.Action
org.apache.struts.actions.DispatchAction
org.apache.struts.actions.MappingDispatchAction
public class MappingDispatchAction
An abstract Action that dispatches to a public
method that is named by the parameter
attribute of
the corresponding ActionMapping. This is useful for developers who prefer
to combine many related actions into a single Action class.
To configure the use of this action in your
struts-config.xml
file, create an entry like this:
<action path="/saveSubscription"
type="org.example.SubscriptionAction"
name="subscriptionForm"
scope="request"
input="/subscription.jsp"
parameter="method"/>
where 'method' is the name of a method in your subclass of MappingDispatchAction that has the same signature (other than method name) of the standard Action.execute method. For example, you might combine the methods for managing a subscription into a single MappingDispatchAction class using the following methods:
for which you would create corresponding <action> configurations that reference this class:
<action path="/createSubscription"
type="org.example.SubscriptionAction"
parameter="create">
<forward name="success" path="/editSubscription.jsp"/>
</action>
<action path="/editSubscription"
type="org.example.SubscriptionAction"
parameter="edit">
<forward name="success" path="/editSubscription.jsp"/>
</action>
<action path="/saveSubscription"
type="org.example.SubscriptionAction"
parameter="save"
name="subscriptionForm"
validate="true"
input="/editSubscription.jsp"
scope="request">
<forward name="success" path="/savedSubscription.jsp"/>
</action>
<action path="/deleteSubscription"
type="org.example.SubscriptionAction"
name="subscriptionForm"
scope="request"
input="/subscription.jsp"
parameter="delete">
<forward name="success" path="/deletedSubscription.jsp"/>
</action>
<action path="/listSubscriptions"
type="org.example.SubscriptionAction"
parameter="list">
<forward name="success" path="/subscriptionList.jsp"/>
</action>
NOTE - Unlike DispatchAction, mapping characteristics may differ between the various handlers, so you can combine actions in the same class that, for example, differ in their use of forms or validation. Also, a request parameter, which would be visible to the application user, is not required to enable selection of the handler method.
Field Summary | |
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private static org.apache.commons.logging.Log |
log
Commons Logging instance. |
Fields inherited from class org.apache.struts.actions.DispatchAction |
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clazz, messages, methods, types |
Fields inherited from class org.apache.struts.action.Action |
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defaultLocale, servlet |
Constructor Summary | |
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MappingDispatchAction()
|
Method Summary | |
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ActionForward |
execute(ActionMapping mapping,
ActionForm form,
javax.servlet.http.HttpServletRequest request,
javax.servlet.http.HttpServletResponse response)
Process the specified HTTP request, and create the corresponding HTTP response (or forward to another web component that will create it). |
protected java.lang.String |
getMethodName(ActionMapping mapping,
ActionForm form,
javax.servlet.http.HttpServletRequest request,
javax.servlet.http.HttpServletResponse response,
java.lang.String parameter)
Returns the method name, given a parameter's value. |
protected ActionForward |
unspecified(ActionMapping mapping,
ActionForm form,
javax.servlet.http.HttpServletRequest request,
javax.servlet.http.HttpServletResponse response)
Method which is dispatched to when there is no value for the parameter in the ActionMapping. |
Methods inherited from class org.apache.struts.actions.DispatchAction |
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cancelled, dispatchMethod, getMethod, getParameter |
Methods inherited from class org.apache.struts.action.Action |
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addErrors, addMessages, execute, generateToken, getDataSource, getDataSource, getErrors, getLocale, getMessages, getResources, getResources, getServlet, isCancelled, isTokenValid, isTokenValid, resetToken, saveErrors, saveErrors, saveErrors, saveMessages, saveMessages, saveToken, setLocale, setServlet |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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private static org.apache.commons.logging.Log log
Constructor Detail |
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public MappingDispatchAction()
Method Detail |
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public ActionForward execute(ActionMapping mapping, ActionForm form, javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws java.lang.Exception
ActionForward
instance describing where and how
control should be forwarded, or null
if the response has
already been completed.
This method dispatches the request to other methods of
MappingDispatchAction
using the 'parameter' attribute of
ActionMapping
and Java Introspection.
execute
in class DispatchAction
mapping
- The ActionMapping used to select this instanceform
- The optional ActionForm bean for this request (if any)request
- The HTTP request we are processingresponse
- The HTTP response we are creating
ActionForward
instance describing where
and how control should be forwarded, or null
if
the response has already been completed.
java.lang.Exception
- if an exception occursprotected ActionForward unspecified(ActionMapping mapping, ActionForm form, javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws java.lang.Exception
MappingDispatchAction
should override this method
if they wish to provide default behavior different than throwing a
ServletException.
unspecified
in class DispatchAction
mapping
- The ActionMapping used to select this instanceform
- The optional ActionForm bean for this request (if any)request
- The HTTP request we are processingresponse
- The HTTP response we are creating
ActionForward
instance describing where
and how control should be forwarded, or null
if
the response has already been completed.
java.lang.Exception
- if an exception occursprotected java.lang.String getMethodName(ActionMapping mapping, ActionForm form, javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, java.lang.String parameter) throws java.lang.Exception
getMethodName
in class DispatchAction
mapping
- The ActionMapping used to select this instanceform
- The optional ActionForm bean for this request (if any)request
- The HTTP request we are processingresponse
- The HTTP response we are creatingparameter
- The ActionMapping
parameter's name
java.lang.Exception
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