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官方Class LookupDispatchAction说明文档（转）

Posted on 2006-07-20 18:18 duyouyou.com 阅读(466) 评论(0)  编辑  收藏 所属分类: web技术
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org.apache.struts.actions

Class LookupDispatchAction



java.lang.Object extended byorg.apache.struts.action.Actionextended byorg.apache.struts.actions.DispatchActionextended byorg.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.MapkeyMethodMap
          Resource key to method name lookup.
protected  java.util.MaplocaleMap
          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
 
Constructor Summary
LookupDispatchAction()
           
 
Method Summary
 ActionForwardexecute(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.MapgetKeyMethodMap()
          Provides the mapping from resource key to method name.
protected  java.lang.StringgetLookupMapName(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.StringgetMethodName(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.MapinitLookupMap(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, saveMessages, saveMessages, saveToken, setLocale, setServlet
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, 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 ActionForwardexecute(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.
Throws:
java.lang.Exception
Since:
Struts 1.2.0
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