CODEWITHSUNDEEP
javascriptjavajqueryjspservlets
user5767955
user5767955

Reputation:

pass value and control from javascript to servlets

I have a jsp file with google map, place autocomplete and few buttons. The submit Button click calls a method in Javascript which inturn passes the jsp page 'input' data to callServlet() method as 'params'. I want to call a servlet page MyServlet and pass the params to it. However my callServlet() executes perfectly but doesn't pass on the control/params to MyServlet. Also How to read params in MyServlet?

Please help me solve it.

JS code:

function callServlet(params) {

    var xmlhttp = new XMLHttpRequest();
    var url = "./mapServlet";

    if (window.XMLHttpRequest)
    {// code for IE7+, Firefox, Chrome, Opera, Safari
        xmlhttp = new XMLHttpRequest();
    } else
    {// code for IE6, IE5
        xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
    }
    console.log(url);
    xmlhttp.onreadystatechange = function ()
    {
        if (xmlhttp.readyState == 4 && xmlhttp.status == 200)
        {
            console.log("Its perfect");
        } else {
            alert(xmlhttp.status);
        }
    }
    xmlhttp.open("POST", url, true);

    xmlhttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
    xmlhttp.setRequestHeader("Content-Length", params.length); // POST request MUST have a Content-Length header (as per HTTP/1.1)       

// params is of json format with key value pairs
        xmlhttp.send(params);     

    }

Servlet code: (Made no changes to this page. Its a simple servlet template)

public class MyServlet extends HttpServlet {

protected void processRequest(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException { ...    }

@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    processRequest(request, response);
}

@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    System.out.print("aaas");
    processRequest(request, response);
}

@Override
public String getServletInfo() {
        return "Short description";
    }// </editor-fold>

}

web.xml

  <servlet>
         <servlet-name>mapServlet</servlet-name>
         <servlet-class>MyServlet</servlet-class>
  </servlet>
  <servlet-mapping>
         <servlet-name>mapServlet</servlet-name>
         <url-pattern>/mapServlet</url-pattern>
  </servlet-mapping>

Upvotes: 1

Views: 1356

Answers (1)

Alexey Soshin
Alexey Soshin

Reputation: 17731

Is there a specific reason you're not using jQuery for that?

Basically, xmlhttp.send(params) expects to receive key=value string, not a Json. If you intend to use bare XMLHttpRequest, you'll need to create this string on your own.

Also, this mapping: var url = "./mapServlet"; may be wrong, as usually you serve code from root, and your JS files are served from resource directory such as /js. Using `var url = "/mapServlet" would be better.

Finally, after you reach your servlet, you can read your parameters using request.getParameter("parameter_name")

To call your server using jQuery start with using jQuery.post() method:

https://api.jquery.com/jquery.post/

$.post( "./mapServlet", params)
  .done(function( data ) {
     console.log("Got ", data);
  });

Upvotes: 1

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