Get data from servlet to JSP without forward?

Question

I need a double value from my servlet to markup in my JSP. My doGet() is sending back formatted HTML tables with values from an ArrayList, so after I got that working I decided to tackle this part.

Servlet:

//Code getting the tables I need

    //Send back the result, this all works good
    response.setContentType("text/html");
    response.setCharacterEncoding("UTF-8");
    response.getWriter().write(returnAsHTML.toString());

What I added to try and get the double value

    //Send back the result

    double test = 20;
    request.setAttribute("Test",test);

    response.setContentType("text/html");
    response.setCharacterEncoding("UTF-8");
    response.getWriter().write(returnAsHTML.toString());

    getServletContext().getRequestDispatcher("index.jsp").forward(request,response);

In JSP:

  <!-- This variable is unresolved -->
  <small>Test : ${Test}</small>

The forwarding seems to crash the whole party. I am new to JSP, I'm sure I am missing something small. I need to keep the response.getWriter() stuff there, it gets a lot of the information I need. Now I just don't know how to get my double values I need as well, because they will be displayed on a whole different part of the page.

Answer 1

You cannot write output to the servletOutputStream and redirect at the same time.

What do you expect from the browser: to display content or to navigate to another page? If the first, don't redirect. If the second, don't display HTML content.

Answer 2

Try using httpsession. Encapsulate whatever object you have using session.setAttribiute(). Then forward it using the sendRedirect() method.

Might be of this kind

HttpSession session=request.getSession();
double test = 20;
session.setAttribute("Test",test);
response.sendRedirect("Index.jsp");

On the JSP page

String s=(String)session.getAttribite("Test");
double d=Double.parseDouble(s);