Is it possible to call a servlet function using JavaScript?

hi everyone!

Is it possible to call a servlet function using javascript function?

thanks in advance.

Not directly. JavaScript executes on the client after the servlet or JSP has sent the HTML page to the browser. You can use Ajax to issue another request to a servlet under script control.

Not sure whether I can understand your requirement correctly. Generally you can set a action on your form and do a form.submit() from javascript.

so that means it is possible in AJAX..?

if so how can i do that..?
here is my sample code.

HTML code:

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
    <%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Rooms and Bed</title>
</head>
<body>
<div title="Update Room and Bed" id="rommbed" align="center">
<form action="" method="post" onsubmit="updateRoomBed();">
<table align="center">
	<tr>
		<th>Room Number </th><td><input type="text" name="roomNo" id="roomRoomNo" onkeypress="return number(event);"><input type="hidden" name="roomno" id="Room_ID"></input></td>
	</tr>
	<tr>
		<th>Room Type </th>
		<td>
			<select name="roomType" id="roomRoomType">
				<option>Public</option>
				<option>Semi-Private</option>
				<option>Private</option>
			</select>
		</td>
	</tr>
	<tr>
		<th>Rate </th><td><input type="text" name="rate" id="roomRate" onkeypress="return numberAndDot(event, this.value)" ></td>
	</tr>
</table>
<br />
<div style="border: 2px;margin-left: auto;margin-right: auto;font-size: 25px;" align="center">Bed</div>
<hr size="3px;" width="300" />
<table align="center">
	<tr>
		<th>Bed ID </th>
		<td>
			<div id="beds">
				<input type="text" name="roombedid" id="bedid" onkeypress="return numberAndDash(event);"><input type="hidden" name="bed_id" id="bed_ID">
			</div>
		</td>
	</tr> 
</table>
<br />
<table align="center">
	<tr>
		<td><input type="submit" value="UPDATE" name="update" />     <input type="reset" value="CANCEL" onclick="self.location.replace('RoomAndBed');" /></td>
	</tr>
</table>
</form>
</div>
</body>
</html>

my JavaScript/AJAX code:

my Servlet code:

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		String roomid = request.getParameter("roomid");
		ArrayList<RoomBean> Rooms = new ArrayList<RoomBean>();
		ArrayList<BedBean> Beds = new ArrayList<BedBean>();
		ArrayList<RoomBedBean> roombed = new ArrayList<RoomBedBean>();
		RoomDAO rDAO = new RoomDAO();
		try{
			if(roomid==null || roomid.equals("")){
				//Rooms = rDAO.displayRooms(false);
				//Beds = rDAO.displayBed(true);
				roombed = rDAO.displayallRoomBed(true);
			}else{
				//Rooms = rDAO.searchRoomID(false, Integer.parseInt(roomid));
				//Beds = rDAO.searchBed(true, Integer.parseInt(roomid));
				roombed = rDAO.searchRoomBed(true, Integer.parseInt(roomid));
			}
		}catch(SQLException e){
			e.printStackTrace();
		}
		
		//request.setAttribute("Rooms", Rooms);
		//request.setAttribute("Beds", Beds);
		request.setAttribute("roombed", roombed);
		
		ServletContext sc = this.getServletContext();
		RequestDispatcher rd = sc.getRequestDispatcher("/Room/RoomBed.jsp");
		rd.forward(request, response);
	}

/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		ArrayList<RoomBean> Rooms = new ArrayList<RoomBean>();
		ArrayList<BedBean> Beds = new ArrayList<BedBean>();
		
		int ret = 0;
		String roomID = request.getParameter("roomNo");
		String roomType = request.getParameter("roomType");
		String rate = request.getParameter("rate");
		String[] bedID = request.getParameterValues("bedID");
		RoomDAO rDAO = new RoomDAO();
		RoomBean bean = new RoomBean(Integer.parseInt(roomID), roomType, Double.parseDouble(rate));
		try{
			Rooms = rDAO.searchRoomID(false, Integer.parseInt(roomID));
			if(Rooms.size()>0){
				rDAO.close();
				System.out.println("Already have a roomID "+roomID);
			}else{
				ret = rDAO.addRoom(false, bean);
				if(ret>0){
					for(int x=0;x<=bedID.length-1;x++){
						Beds = rDAO.searchBedID(false, bedID[x]);
						if(Beds.size()>0){
							rDAO.deleteRoom(true, Integer.parseInt(roomID));
							System.out.println("Bed ID "+bedID[x]+" has already in the database!");
							break;
						}else{
							BedBean bed = new BedBean(Integer.parseInt(roomID), null, bedID[x]);
							rDAO.AddBed(false, bed);
						}
					}
				}else{
					rDAO.close();
				}
			}
		}catch(SQLException e){
			e.printStackTrace();
		}
		 doGet(request, response);
	}

@SuppressWarnings("unused")
	private void add(HttpServletRequest request, HttpServletResponse response) throws SQLException, ServletException, IOException {
		System.out.println("okkkkkkkkkkkkkkk!!!");
		String roomID = request.getParameter("roomNo");
		String roomType = request.getParameter("roomType");
		String rate = request.getParameter("rate");
		String bedID = request.getParameter("roombedid");
		String oldRoomID = request.getParameter("roomno");
		String oldBedID = request.getParameter("bed_id");
		
		RoomDAO rDAO = new RoomDAO();
		RoomBean room = new RoomBean(Integer.parseInt(roomID), roomType, Double.parseDouble(rate));
		BedBean bed = new BedBean(Integer.parseInt(roomID), "", bedID);
		try{
			rDAO.updateRoom(false, room, Integer.parseInt(oldRoomID));
			rDAO.updateBed(true, bed, oldBedID);
		}catch(SQLException e){
			e.printStackTrace();
		}
		
		doGet(request, response);
	}

now, how can i call the add() function in the ajax?

please help me.

You can't call a method directly, you can GET or POST a request to the servlet.

If you really want a sort of function call, you can look into DWR (which uses Ajax and requests to make it seem like the function is being called).

Yes it is possible to call a servlet using javascript(JSP).
one example is using the <form> tag...

here is a sample...
<form method ="get" action="myservlet">
<input type="submit" name="aaaa" value="zzz">
</form>

In this sample, your javascript would call a servlet with a filename myservlet.java upon clicking the button. Take note that you need not put the extension name of the servlet if a javascript would call it.

Of course it's possible to invoke a servlet with a form -- that's not what is being asked here.

Sorry I didn't make myself clear.... if you want to call the add() function, then just create a seperate servlet which would contain all the methods in your add() function and call the newly created servlet... then would be as if you called the add() itself.... well just trying to help...

The AJAX recommendation was a good suggestion. It's what we use. Here is a little portion of code were we call a servlet (CreateProgramCopy) from a JSP page using javascript. One thing to notice, that in this example is that we call this servlet "synchronously" which means the javascript code waits for the servlet to finish before moving on. In this implementation we found that if we made an asynchronous call we ended up having too many open connections because this code is called many times if a user selects multiple records to copy. For example of they select 20 records to copy, this code will run 20 times and we end up with 20 connections to our server and that was too much. The user has to wait a brief period before this completes but that was acceptable.

Why can't you send the parameters in your add method as a POST to your servlet and go from there?