Getting error "getOutputStream () has already been called for this response"

I am showing a report of some event. I need the controller to show a popup to save and open.

I have already set the file in the answer, after setting the answer, I return the view.

Now my question is:

I am getting the error "java.lang.IllegalStateException: getOutputStream () has already been called for this response"

In my class class, I wrote the following code:

...... some code .......

InputStream is =
        new FileInputStream(new File("c:/reports/test_jasper.pdf"));
            response.setHeader("Content-Disposition","attachment;filename=\"test_jasper.pdf\"");
            OutputStream opStream = response.getOutputStream();
            IOUtils.copy(is, opStream);
            response.flushBuffer();
            HttpServletResponse response1 = new HttpServletResponse();



        model.addAttribute(ABC, new abc());

        model.addAttribute(DEF, new def());
        return SOME_VIEW;

      

        
        
        
      

    

Framework:

Spring-MVC, hibernate

An exception:

java.lang.IllegalStateException: getOutputStream () has already been called for this response

Desired O / P: I want the response to display a popup for the file and would like the browser to redirect to a different view.