Passing a URL parameter from JSP to Servlet

Question

I'm trying to pass a URL parameter from a JSP to a Sevlet. My URL is

/portal/faces/student.jsp?owner_id=1030303i

In my JSP i added this

<form action="steg" method="post" enctype="multipart/form-data">
     <input type='text' value='<%=request.getParameter("owner_id")%>' id="owner"/>
     <input type="file" name="file" size="50"  />
            <br />             
            <input type="submit" value="Steganograph" />
        </form>

However, in the servlet i did this,

              String owner = request.getParameter("owner");
              System.out.println("aaaaaaaaaaaaaaaa"+owner);
              response.sendRedirect("stegsuccess.jsp?owner_id="+owner);

the result that is printed out is null. Is something wrong there? Anyone that knows how to fix this? Please advice. Thanks :)

score 1 · Answer 1 · edited May 23 '17 at 12:03

There are 2 problems in your code:

You didn't give the input field a name. You expected that the id attribute of the input element is been used as request parameter name. But this is not true. It's the name attribute.
```
<input type="text" name="owner" value="${fn:escapeXml(param.owner_id)}" />
```
(note: I've taken the liberty to seal a XSS attack hole in the value attribute for you)
You're using multipart/form-data encoding and yet expecting that the request parameters are available by HttpServletRequest#getParameter(). This is by default not supported. This will only work if you're using a servlet with @MultipartConfig on a Servlet 3.0 compatible container. Or maybe you're working on an existing project and someone else has already invented a servlet filter which transparently parses multipart/form-data requests and fills the request parameter map before passing the request to the servlet. In any case, make sure that you understand how to parse multipart/form-data requests: How to upload files to server using JSP/Servlet?

score 0 · Answer 2 · edited May 23 '17 at 10:25

0

What version of servlets are you using?

multipart/form-data encoded requests are indeed not by default supported by the Servlet API prior to version 3.0. The Servlet API parses the parameters by default using application/x-www-form-urlencoded encoding. When using a different encoding, the request.getParameter() calls will all return null. When you're already on Servlet 3.0 (Glassfish 3, Tomcat 7, etc), then you can use HttpServletRequest#getParts() instead.

From https://stackoverflow.com/a/3337115/139010. See also Issue with Servlet Multipart request.

edited May 23 '17 at 10:25

Community

1
1

answered Sep 11 '12 at 13:21

Matt Ball

354,903
100
647
710

I'm not really too sure what's the version I'm using. I tried using the links you've given me. But it seems that its not working with getValues and returning me to a wrong page. Any idea if there is other method for this? – user1651129 Sep 11 '12 at 13:47
Look in web.xml. The top-level element is `` and its `version` and `xsi:schemaLocation` attributes are a hint as to what servlet version you're using. – Matt Ball Sep 11 '12 at 14:27

Ratnakar.class · Answer 3 · 2012-09-11T18:28:54.420

0

sendRedirect() method wont carry the request object forward. Instead use RequestDispatcher rd = request.getRequestDispatcher("yourpage.jsp");rd.forward(req, res) method which forwards the request object and so the request parameters.

edited Sep 11 '12 at 18:28

answered Sep 11 '12 at 18:22

Ratnakar.class

301
5
12

This is correct from Servlet code of user. If you look at JSP code,the request is `enctype="multipart/form-data"`.So, `request.getParameter("paramName");` will return NULL. – Hardik Mishra Sep 12 '12 at 04:38

Passing a URL parameter from JSP to Servlet

3 Answers3