Question

I’m learning Java Servlets and the book I’m using has an example on file upload , when I do it I get the following error

The method getInputStream() is undefined for the type HttpServletResponse

When I try to use

ServletInputStream sis =  response.getInputStream();

One of the solution eclipse offered was

ServletInputStream sis =  ((ServletRequest) response).getInputStream();

And using that resulted in the following

java.lang.ClassCastException:
org.apache.catalina.connector.ResponseFacade cannot be cast

to javax.servlet.ServletRequest ShowForm.doPost(ShowForm.java:37)
javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)

Here is my full code:

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.ServletInputStream;
import javax.servlet.ServletRequest;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class ShowForm
 */
@WebServlet("/ShowForm")
public class ShowForm extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public ShowForm() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

            doPost(request,response);
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        response.setContentType("text/plain");
        PrintWriter out = response.getWriter();

        ServletInputStream sis =  response.getInputStream();
        for (int i = sis.read();i != -1; i = sis.read())
            {

                out.print((char)i);

            }
    }
}

Answer 1

That’s because ServletResponse/HttpServletResponse doesn’t have the getInputStream().
You might actually want to use getInputStream from HttpServletRequest.

request.getInputStream()