Passing data between jQuery and Servlet

Question

I have a HTML form:

<head>

    <script src="//ajax.googleapis.com/ajax/libs/jquery/1.5.1/jquery.js"></script>
    <script type="text/javascript">

        $(document).ready(function() {

            $('#convert').click(function(){

                //pairno tis times ap tin forma
                var amount = $('#amount').val();
                var from = $('#from').val();
                var to = $('#to').val();

                //kano ta dedomena ena koino string
                var dataString = "amount=" + amount + "&from=" + from + "&to=" + to;

                $.ajax({
                type: "POST",
                url: "CurrencyConverter",
                success: function(data){
                //pairno ta dedomena
                $('#results').show();

                //vazo ta dedomena sto results div tag.
                $('#results').html(data);
            }
         });
        });

        $('#swap').click(function() { 
            
            s1=$('#to').val();  
            s0=$('#from').val();  
            $('#to').val(s0);  
            $('#from').val(s1); 
        });
});

</script>


</head>
<body>
    <div class="data">
        <label for="from">Μετάτρεψε:</label>
        <input type="text" name="amount" id="amount" value="1" />
    </div>

    <div class="data">
        <label for="fromCurrency">από:</label>
        <select name="from" id="from">
          <option selected="" value="EUR">Euro - EUR</option>
          <option value="USD">United States Dollars - USD</option>
          <option value="GBP">United Kingdom Pounds - GBP</option>
          <option value="CAD">Canada Dollars - CAD</option>
        </select>
    </div>

    <div class="data">
        <label for="to">σε:</label>
        <select name="to" id="to">
          <option value="USD">United States Dollars - USD</option>
          <option value="GBP">United Kingdom Pounds - GBP</option>
          <option value="CAD">Canada Dollars - CAD</option>
          <option value="AUD">Australia Dollars - AUD</option>
          <option value="JPY">Japan Yen - JPY</option>
        </select>
    </div>
    <div class="data">
        <input type="submit" value="Μετατροπή">
        <input type="submit" name="swap" id="swap" value="αντάλλαξέ τα!">
    </div>
</div>

<div id="results"></div>
</body>
</html>

I want to extract the data from that form using the script on the top and send them to my servlet.

Here is my servlet code:

package com.example.web;
import com.example.model.*;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;
import java.lang.*;
import java.util.*;

public class CurrencySelect extends HttpServlet{

        public void doPost(HttpServletRequest request,HttpServletResponse response)throws IOException, ServletException{

            //response.setContentType("text/html;charset=UTF-8");

            String from = request.getParameter("from");

            String to = request.getParameter("to");

            String amount = request.getParameter("amount");

            CurrencyGenerator curr = new CurrencyGenerator();

            String res = curr.GetCurrency(from,to,amount);  

            out.println(res);

}

}

And here is my web.xml file:

    <?xml version="1.0" encoding="ISO-8859-1"?>
<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
    Version="2.4">
    <servlet>
        <servlet-name>CurrencyConverter</servlet-name>
        <servlet-class>com.example.web.CurrencySelect</servlet-class>
    </servlet>
    <servlet>
        <servlet-name>CodeReturn</servlet-name>
        <servlet-class>com.example.web.CodeReturn</servlet-class>
    </servlet>
    <servlet>
        <servlet-name>Redirect</servlet-name>
        <servlet-class>com.example.web.Redirect</servlet-class>
    </servlet>
    <servlet>
        <servlet-name>ListenerTester</servlet-name>
        <servlet-class>com.example.web.ListenerTester</servlet-class>
    </servlet>


    <servlet-mapping>
        <servlet-name>CurrencyConverter</servlet-name>
        <url-pattern>/CurrencyConverter.do</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>CodeReturn</servlet-name>
        <url-pattern>/CodeReturn.do</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>Redirect</servlet-name>
        <url-pattern>/Redirect.do</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>ListenerTester</servlet-name>
        <url-pattern>/ListenTest.do</url-pattern>
    </servlet-mapping>

    <context-param>
        <param-name>report</param-name>
        <param-value>report.html</param-value>
    </context-param> 

    <listener>
        <listener-class>com.example.model.MyServletContextListener</listener-class>
    </listener> 

</web-app>

I want to print the result in my html form page in a div I have in the end called results. I had the same script made with php and everything was working fine but with servlets. I can get my results in a new page, but I cannot take them in the same HTML page. How can I solve it?

score 7 · Accepted Answer · edited May 23 '17 at 10:24

Here,

$.ajax({
    type: "POST",
    url: "CurrencyConverter",
    success: function(data) {
        $('#results').show();
        $('#results').html(data);
    }
});

you have 2 problems:

Your servlet is mapped on /CurrencyConverter.do, but yet you're trying to invoke it on /CurrencyConverter. You need to fix the URL.
You are not passing the query string dataString at all. You need to pass it as data option.

So, this should do:

$.ajax({
    type: "POST",
    url: "CurrencyConverter.do",
    data: dataString,
    success: function(data) {
        $('#results').show();
        $('#results').html(data);
    }
});

Note that although cobbling the query string together yourself may work in most cases, it will fail whenever the input values contain special characters. You want to pass a JS object along instead as shown in Akhil's answer. But much better is to just use a <form> and jQuery.serialize(). See also Simple calculator with JSP/Servlet and Ajax for a kickoff example.

score 2 · Answer 2 · answered Nov 15 '11 at 12:49

2

/*
 Hi ,

just try changing the following code in javascript 

*/

  var dataString ={"amount":amount,"from":from,"to":to};

  $.ajax({
                type: "POST",
                data:dataString,
                url: "CurrencyConverter",
                success: function(data){
                //pairno ta dedomena
                $('#results').show();

                //vazo ta dedomena sto results div tag.
                $('#results').html(data);
            }
         });

answered Nov 15 '11 at 12:49

Akhil Thayyil

9,263
6
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48

it does nothing man that is the strange thing it return nothing it respond to no where if i change my html code and place a
above the form and a
and delete the script on the top everything works fine but i get the result on a new html page – Mpampinos Holmens Nov 15 '11 at 13:10

score -2 · Answer 3 · answered Nov 15 '11 at 12:47

A JSP page is itself a servlet...the servlet container compiles it behind the scenes. So you can refer to the request object inside the JSP file itself. So if the form's action is the name of the HTML page itself, then the results of the form will be visible. So for example you could put this in your JSP:

<%= request.getParameter("amount")%>

You can also have your JSP action point at a servlet, and then have the servlet redirect back to the JSP. I don't remember the details off the top of my head, but again, this would mean that the request parameters would be visible to the JSP page.

first i don't have a .jsp page, second i want to get the data from the form to the servlet and back to the page which holds the form! — Mpampinos Holmens, Nov 15 '11 at 13:12

Passing data between jQuery and Servlet

3 Answers3

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