Error in AJAX code

[nnaveenraju]

Hi Gurus,

I am new to Ajax and JAVA.
I am able to call the servlet class from the JSP page using AJAX.

The servlet class is called successfully.

I am processing some data and the data has to passed back to the front end JSP.

I have used the following code

**********************JAVA Script:***************************

function getRequestObject() {
  if (window.ActiveXObject) {
    return(new ActiveXObject("Microsoft.XMLHTTP"));
  } else if (window.XMLHttpRequest) {
    return(new XMLHttpRequest());
  } else {
    return(null);
  }
}
 
function displayTimeInCity(val) {
  alert('test');
  alert(val);
  var address = "start";
  alert(document.getElementById('F_010_ADDRESSTYPE'));
  alert(document.getElementById('F_010_ADDRESSTYPE').value);
  var addr = document.getElementById("F_010_ADDRESSTYPE").value;
  alert(addr);
  var data = "addr=" + escape(addr) + "&useHTML=true";
  sendRequestWithData(address, data, showResponseText);
}
 
function sendRequestWithData(address, data, responseHandler) {
  request = getRequestObject();
  request.onreadystatechange = responseHandler;
  request.open("POST", address, true);
  request.setRequestHeader("Content-Type", 
                           "application/x-www-form-urlencoded");
  alert(address);
  request.send(data);
}
 
function showResponseText() {
  if ((request.readyState == 4) &&
      (request.status == 200)) {
      alert(request.responseText);
    document.getElementById("F_010_STREET1").value =
      request.responseText;
  }
}

*************************servlet Class*********************************

//Function called as "doPost" in this servlet....
public String doHandleEvent(String eventName, HttpServletRequest request, HttpServletResponse response)  throws ServletException, IOException 
  {
// Set the name of the JSP that has to be called when this method is finished.
// INITIAL_JSP ist defined in the interface Constants.java
    System.out.println(" in events");
    String nextJSP = INITIAL_JSP.jsp;
 
                //Data passed as query parameter to the servlet class.....
    if (request.getParameter("addr")!=null)
    {
       response.setHeader("Cache-Control", "no-cache");
       response.setHeader("Pragma", "no-cache");
       response.setContentType("text/html");
       //System.out.println("Addr = "+request.getParameter("addr"));
       //PrintWriter out = response.getWriter();
       //out.print("naveen");
       RequestDispatcher dispatcher =
       request.getRequestDispatcher("naveen");
       dispatcher.include(request, response);
       return nextJSP;
    }
 
return nextJSP; //nextJSP is the String param with "inital.jsp"
}

Now my question is
How do i get the String "Naveen" in the JAVA Script Code...
"request.responseText"

I am getting the following error:

************************************************** ****************************************
<h1>Error: 500</h1><h2>Location: /INFOXPHARMA/start</h2><b>Internal Servlet Error:</b><br><pre>java.lang.IllegalStateException: Cannot forward as OutputStream or Writer has already been obtained at org.apache.tomcat.facade.RequestDispatcherImpl.doF orward(RequestDispatcherImpl.java:178) at org.apache.tomcat.facade.RequestDispatcherImpl.for ward(RequestDispatcherImpl.java:162) at com.sap.ip.me.api.runtime.jsp.AbstractMEHttpServle t.dispatchRequest (AbstractMEHttpServlet.java:907) at com.sap.ip.me.api.runtime.jsp.AbstractMEHttpServle t.doGetNotThreadSafe(AbstractMEHttpServlet.java:34 8) at com.sap.ip.me.api.runtime.jsp.AbstractMEHttpServle t.doGet(AbstractMEHttpServlet.java :689) at com.sap.ip.me.api.runtime.jsp.AbstractMEHttpServle t.doPost(AbstractMEHttpServlet.java:706) at javax.servlet.http.HttpServlet.service(HttpServlet .java:760) at com.sap.ip.me.api.runtime.jsp.AbstractMEHttpServle t.service (AbstractMEHttpServlet.java:313) at javax.servlet.http.HttpServlet.service(HttpServlet .java:853) at org.apache.tomcat.core.ServletWrapper.doService(Se rvletWrapper.java:405) at org.apache.tomcat.core.Handler.service(Handler.jav a :287) at org.apache.tomcat.core.ServletWrapper.service(Serv letWrapper.java:372) at org.apache.tomcat.core.ContextManager.internalServ ice(ContextManager.java:806) at org.apache.tomcat.core.ContextManager.service(Cont extManager.java :752) at org.apache.tomcat.service.http.HttpConnectionHandl er.processConnection(HttpConnectionHandler.java:21 3) at org.apache.tomcat.service.TcpWorkerThread.runIt(Po olTcpEndpoint.java:416) at org.apache.tomcat.util.ThreadPool$ControlRunnable. run (ThreadPool.java:501) at java.lang.Thread.run(Thread.java:534)</pre>

************************************************** ****************************************


Thanking you in advance.
Naveen

[dmjpro]

This is a Java related Question.

What does it mean?

RequestDispatcher dispatcher =
       request.getRequestDispatcher("naveen");
 

Debasis Jana

[nnaveenraju]

This is a Java related Question.

What does it mean?

RequestDispatcher dispatcher =
       request.getRequestDispatcher("naveen");
 

Debasis Jana

Hi Debasis Jana,

Thanks for the reply.

This is the dispather object used to return any string along with the request object.

RequestDispatcher dispatcher =
request.getRequestDispatcher("naveen");

I am also using the
PrintWriter out = response.getWriter();
out.print("naveen");

in the new code.
This is used to output the text from the context.

Anywaz, I have resolved this issue.
I am using the "public String doHandleEvent" in the code I mentioned. This is extended from the "AbstractMEHttpServlet" class. This class is extended from the SAP ME. Which I think was cutomly used by SAP.

I have created my own servlet class using the actual "HttpServlet" class and the

PrintWriter out = response.getWriter();
out.print("naveen");

to return the string required and am able to read the string in the Javascript.

Anywaz thanks you again for your interest.

Naveen

[dmjpro]

Glad to hear it.........Post back again.

Debasis Jana