| A utility class to generate multipart/x-mixed-replace responses,
the kind of responses that implement server push. Note that Microsoft
Internet Explorer does not understand this sort of response.
To use this class, first construct a new MultipartResponse
passing to its constructor the servlet's response parameter.
MultipartResponse uses the response object to fetch the
servlet's output stream and to set the response's content type.
Then, for each page of content, begin by calling startResponse()
passing in the content type for that page. Send the content for the
page by writing to the output stream as usual. A call to
endResponse() ends the page and flushes the content so the
client can see it. At this point a sleep() or other delay
can be added until the next page is ready for sending.
The call to endResponse() is optional. The
startResponse() method knows whether the last response has
been ended, and ends it itself if necessary. However, it's wise to
call endResponse() if there's to be a delay between the
time one response ends and the next begins. It lets the client display
the latest response during the time it waits for the next one.
Finally, after each response page has been sent, a call to the
finish() method finishes the multipart response and sends a
code telling the client there will be no more responses.
For example:
MultipartResponse multi = new MultipartResponse(res);
multi.startResponse("text/plain");
out.println("On your mark");
multi.endResponse();
try { Thread.sleep(1000); } catch (InterruptedException e) { }
multi.startResponse("text/plain");
out.println("Get set");
multi.endResponse();
try { Thread.sleep(1000); } catch (InterruptedException e) { }
multi.startResponse("image/gif");
ServletUtils.returnFile(req.getRealPath("/images/go.gif"), out);
multi.finish();
See Also: ServletUtils
author:
Jason Hunter, Copyright © 1998
version:
1.0, 98/09/18 | 