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.
private static org.apache.commons.logging.Log LOG
          Commons Logging instance.
 
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, getParameter, 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

LOG

private static final org.apache.commons.logging.Log LOG
Commons Logging instance.

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


Copyright 2000-2006 - The Apache Software Foundation