I am not sure what they mean exactly, but maybe they refer to the following difference.
Consider a jsp like this:
and a simular jsp with calling the get method:
And a Servlet (with a correct mapping) which just forwards (from the doGet() and the doPost() method) to another jsp where it shows the text fields
If you now refresh the page which was made after a doGet() it just refreshes, but if you refresh the page after a doPost(), the browser will ask you if you want to re-submit your previous data (you can't re-read it)
Thanks Frits! Normally, How does the container handles the request and response objects? For response, it's use the ServletOutputStream for writing binary data, and PrintWriter is a convenient way of writing, and PrintWriter is wrapped around ServletOutputStream. But what about request object? I know, there are two objetcts, ServletInputStream and BufferedReader. Defuulty, on which object is used to get the body of the request, such as getAttribute(), getParameter(), etc?
Creator of Enthuware JWS+ V6
For the request it is simular, you either use the getInputStream() which returns a ServletInputStream (just try it yourself and read the stream) or you use the convenient methods like getParameter() and getAttribute(). (the implementation of these methods probably use the getInputStream as well to obtain the data....)