Problem if i use ajax in struts

Question

hi,
i am working on struts, now i got one problem if i use ajax in jsp.
In my jsp page i have two dropdown lists, according to the first dropdown value second dropdown result will getting from the database by calling an action class.
but my requirement is for getting the second dropdown result page should not be refresh for this i am using ajax.
in ajax how can we call one action class what should we return in actionmapping.
If any one already written some code for this please send it to me.
please can anyone help on this its very urgent for me.

Answer 1

Hi
First of all you have to write on fnRetrieveURL which will be responsible for getting the connection and XML communication.
               function fnRetrieveURL(strURL, strFnProcessStateChange)
                    if(window.XMLHttpRequest)
                         varXMLrequest = new XMLHttpRequest();
                         varXMLrequest.onreadystatechange = eval(strFnProcessStateChange);
                         try
                              varXMLrequest.open("POST",strURL,true);
                         catch(Exception)
                              alert("Problem in Getting data ");
                         varXMLrequest.send(null);
                    else if(window.ActiveXObject)
                         varXMLrequest = new ActiveXObject("Microsoft.XMLHTTP");
                         if(varXMLrequest)
                              varXMLrequest.onreadystatechange =eval(strFnProcessStateChange);
                              varXMLrequest.open("POST",strURL,true);
                              varXMLrequest.send();
               }This method will be called in user written method in which request will be submitted to action class.
               function fnGetAreaForRegion()
                    var iRegion = document.getElementById("region").value;
                    var strURL = "../getAreaForRegion.do"
                    strURL = strURL+"?methodName="+"getAreaForRegion";
                    strURL = strURL+"&controlName="+"area";
                    strURL = strURL+"&iRegion="+iRegion ;
                    fnRetrieveURL(strURL,"fnOnReturnFromRegion");
               }Then there will be one on Return method i.e the method which will be called when the response will come back to JSP from fnGetAreaforRegion.
               function fnOnReturnFromRegion()
                    if (varXMLrequest.readyState == 4)
                         if(varXMLrequest.status == 200)
                              var strSubClassValue = varXMLrequest.responseText;
                              if(strSubClassValue != '')
                                var strArray = strSubClassValue.split(",");
                                   var iLength = strArray.length;
                                   var strName = new Array();
                                   var strID = new Array();
                                   var j=0;
                                   for(var i =0 ; i< iLength;i=i+2)
                                        strName[j] = strArray;
                                        j++;
                                   var k=0;
                                   for(var i =1 ; i< iLength;i=i+2)
                                        strID[k] = strArray[i];
                                        k++;
                                   var iNewLength = strID.length;
                                   var optnSelect = document.createElement("OPTION");
                                   optnSelect.text = 'Select';
                                   optnSelect.value = '';
                                   document.getElementById("area").options.add(optnSelect);
                                   for(var i =0 ; i< iNewLength;i++)
                                        var optn = document.createElement("OPTION");
                                        optn.text = strName[i];
                                        optn.value = parseInt(strID[i]);
                                        document.getElementById("area").options.add(optn);
Rest modification in struts-config, you can do by urself. and also you have to write one action class which will take care of parameters and all business logic.
Above code you can reuse by bit modification. Action class you have to write by your own.
let me know if you still face any issues