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java.lang.Object | +--org.apache.struts.action.Action | +--org.apache.struts.actions.DispatchAction
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.
Field Summary | |
protected java.lang.Class |
clazz
The Class instance of this DispatchAction class. |
protected static org.apache.commons.logging.Log |
log
Commons Logging instance. |
protected static MessageResources |
messages
The message resources for this package. |
protected java.util.HashMap |
methods
The set of Method objects we have introspected for this class, keyed by method name. |
protected java.lang.Class[] |
types
The set of argument type classes for the reflected method call. |
Fields inherited from class org.apache.struts.action.Action |
defaultLocale, servlet, token |
Constructor Summary | |
DispatchAction()
|
Method Summary | |
protected ActionForward |
cancelled(ActionMapping mapping,
ActionForm form,
javax.servlet.http.HttpServletRequest request,
javax.servlet.http.HttpServletResponse response)
Method which is dispatched to when the request is a cancel button submit. |
protected ActionForward |
dispatchMethod(ActionMapping mapping,
ActionForm form,
javax.servlet.http.HttpServletRequest request,
javax.servlet.http.HttpServletResponse response,
java.lang.String name)
Dispatch to the specified method. |
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.reflect.Method |
getMethod(java.lang.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 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 specified request parameter included in the request. |
Methods inherited from class org.apache.struts.action.Action |
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 |
|
Field Detail |
protected java.lang.Class clazz
DispatchAction
class.protected static org.apache.commons.logging.Log log
protected static MessageResources messages
protected java.util.HashMap methods
protected java.lang.Class[] types
Constructor Detail |
public DispatchAction()
Method Detail |
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.execute
in class Action
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 creatingjava.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
DispatchAction
should override this method if they wish
to provide default behavior different than throwing a ServletException.protected ActionForward cancelled(ActionMapping mapping, ActionForm form, javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws java.lang.Exception
DispatchAction
should override this method if
they wish to provide default behavior different than returning null.protected ActionForward dispatchMethod(ActionMapping mapping, ActionForm form, javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, java.lang.String name) throws java.lang.Exception
protected java.lang.reflect.Method getMethod(java.lang.String name) throws java.lang.NoSuchMethodException
execute
method does.name
- Name of the method to be introspectedjava.lang.NoSuchMethodException
- if no such method can be foundprotected 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
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
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