org.apache.struts.actions

Class 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

private static Log
LOG
Commons Logging instance.
protected Map
keyMethodMap
Resource key to method name lookup.
protected 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

Method Summary

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 abstract Map
getKeyMethodMap()
Provides the mapping from resource key to method name.
protected String
getLookupMapName(HttpServletRequest request, String keyName, ActionMapping mapping)
Lookup the method name corresponding to the client request's locale.
protected String
getMethodName(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response, String parameter)
Returns the method name, given a parameter's value.
private Map
initLookupMap(HttpServletRequest request, 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, execute, getMethod, getMethodName, getParameter, unspecified

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

addErrors, addMessages, execute, execute, generateToken, getDataSource, getDataSource, getErrors, getLocale, getMessages, getResources, getResources, getServlet, isCancelled, isTokenValid, isTokenValid, resetToken, saveErrors, saveErrors, saveErrors, saveMessages, saveMessages, saveToken, setLocale, setServlet

Field Details

LOG

private static final Log LOG
Commons Logging instance.

keyMethodMap

protected Map keyMethodMap
Resource key to method name lookup.

localeMap

protected Map localeMap
Reverse lookup map from resource value to resource key.

Method Details

execute

public ActionForward execute(ActionMapping mapping,
                             ActionForm form,
                             HttpServletRequest request,
                             HttpServletResponse response)
            throws 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 interface 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
Returns:
Describes where and how control should be forwarded.

getKeyMethodMap

protected abstract Map getKeyMethodMap()
Provides the mapping from resource key to method name.
Returns:
Resource key / method name map.

getLookupMapName

protected String getLookupMapName(HttpServletRequest request,
                                  String keyName,
                                  ActionMapping mapping)
            throws 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.
Since:
Struts 1.2.0

getMethodName

protected String getMethodName(ActionMapping mapping,
                               ActionForm form,
                               HttpServletRequest request,
                               HttpServletResponse response,
                               String parameter)
            throws Exception
Returns the method name, given a parameter's value.
Overrides:
getMethodName in interface 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

initLookupMap

private Map initLookupMap(HttpServletRequest request,
                          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.

Copyright B) 2000-2007 - The Apache Software Foundation