Apache Struts API Documentation: Class LookupDispatchAction

Apache Struts API

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org.apache.struts.actions Class LookupDispatchAction

java.lang.Object
  |
  +--org.apache.struts.action.Action
        |
        +--org.apache.struts.actions.DispatchAction
              |
              +--org.apache.struts.actions.LookupDispatchAction
public abstract class LookupDispatchAction
extends DispatchAction

An abstract Action that dispatches to the subclass mapped execute method. This is useful in cases where an HTML form has multiple submit buttons with the same name. The button name is specified by the parameter property of the corresponding ActionMapping. To configure the use of this action in your struts-config.xml file, create an entry like this:

   <action path="/test"
           type="org.example.MyAction"
           name="MyForm"
          scope="request"
          input="/test.jsp"
      parameter="method"/>

which will use the value of the request parameter named "method" to locate the corresponding key in ApplicationResources. For example, you might have the following ApplicationResources.properties:

    button.add=Add Record
    button.delete=Delete Record

And your JSP would have the following format for submit buttons:

   <html:form action="/test">
    <html:submit property="method">
      <bean:message key="button.add"/>
    </html:submit>
    <html:submit property="method">
      <bean:message key="button.delete"/>
    </html:submit>
  </html:form>

Your subclass must implement both getKeyMethodMap and the methods defined in the map. An example of such implementations are:

  protected Map getKeyMethodMap() {
      Map map = new HashMap();
      map.put("button.add", "add");
      map.put("button.delete", "delete");
      return map;
  }

  public ActionForward add(ActionMapping mapping,
          ActionForm form,
          HttpServletRequest request,
          HttpServletResponse response)
          throws IOException, ServletException {
      // do add
      return mapping.findForward("success");
  }

  public ActionForward delete(ActionMapping mapping,
          ActionForm form,
          HttpServletRequest request,
          HttpServletResponse response)
          throws IOException, ServletException {
      // do delete
      return mapping.findForward("success");
  }
  


  Notes - If duplicate values exist for the keys returned by
  getKeys, only the first one found will be returned. If no corresponding key
  is found then an exception will be thrown. You can override the
  method unspecified to provide a custom handler. If the submit
  was cancelled (a html:cancel button was pressed), the custom
  handler cancelled will be used instead.


















Field Summary





protected  java.util.Map
keyMethodMap



          Resource key to method name lookup.		





protected  java.util.Map
localeMap



          Reverse lookup map from resource value to resource key.		




 




Fields inherited from class org.apache.struts.actions.DispatchAction




clazz, log, messages, methods, types




 




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




defaultLocale, servlet, token




 








Constructor Summary




LookupDispatchAction()



           		




 








Method Summary





 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 abstract  java.util.Map
getKeyMethodMap()



          Provides the mapping from resource key to method name.		





protected  java.lang.String
getLookupMapName(javax.servlet.http.HttpServletRequest request,
                 java.lang.String keyName,
                 ActionMapping mapping)



          Lookup the method name corresponding to the client request's locale.		





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.		





private  java.util.Map
initLookupMap(javax.servlet.http.HttpServletRequest request,
              java.util.Locale userLocale)



          This is the first time this Locale is used so build the reverse lookup Map.		




 




Methods inherited from class org.apache.struts.actions.DispatchAction




cancelled, dispatchMethod, getMethod, unspecified




 




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




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




 











Field Detail







localeMap


protected java.util.Map localeMap




Reverse lookup map from resource value to resource key.






keyMethodMap


protected java.util.Map keyMethodMap




Resource key to method name lookup.










Constructor Detail







LookupDispatchAction


public LookupDispatchAction()














Method Detail







execute


public ActionForward execute(ActionMapping mapping,
                             ActionForm form,
                             javax.servlet.http.HttpServletRequest request,
                             javax.servlet.http.HttpServletResponse response)
                      throws java.lang.Exception




Process the specified HTTP request, and create the corresponding HTTP
  response (or forward to another web component that will create it).
  Return an ActionForward instance describing where and how
  control should be forwarded, or null if the response has
  already been completed.


Overrides:
execute in class DispatchAction






Parameters:
mapping - The ActionMapping used to select this instance
request - The HTTP request we are processing
response - The HTTP response we are creating
form - The optional ActionForm bean for this request (if any)
Returns:
Describes where and how control should be forwarded.
Throws:
java.lang.Exception - if an error occurs










initLookupMap


private java.util.Map initLookupMap(javax.servlet.http.HttpServletRequest request,
                                    java.util.Locale userLocale)




This is the first time this Locale is used so build the reverse lookup Map.
 Search for message keys in all configured MessageResources for
 the current module.






getKeyMethodMap


protected abstract java.util.Map getKeyMethodMap()




Provides the mapping from resource key to method name.


Returns:
Resource key / method name map.










getLookupMapName


protected java.lang.String getLookupMapName(javax.servlet.http.HttpServletRequest request,
                                            java.lang.String keyName,
                                            ActionMapping mapping)
                                     throws javax.servlet.ServletException




Lookup the method name corresponding to the client request's locale.


Parameters:
request - The HTTP request we are processing
keyName - The parameter name to use as the properties key
mapping - The ActionMapping used to select this instance
Returns:
The method's localized name.
Throws:
javax.servlet.ServletException - if keyName cannot be resolved
Since: 
Struts 1.2.0












getMethodName


protected 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




Returns the method name, given a parameter's value.


Overrides:
getMethodName in class DispatchAction






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





















  

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