The core of my problem is as follows:
I have bracketed all my JSP's with a try catch block. If I encounter any
exception while
processing a JSP page, then I redirect to a different page with the error
message from
the exception trace.
However, I dont want to perform a sendRedirect with a get operation, because
the url
is lengthy and ugly. Instead I would love to do a post, get the response from
the url connection,
remove the contents of the current print writer and replace it with that of the
response
from the url connection.
I don't know how to dis-associate the print writer from the response object
which has some
partial content, generated by the servlet.
-Srikanth
[EMAIL PROTECTED] wrote:
> How about using another writer to capture the response data until you know
> that no error occured. If an error occurs, then throw out the captured
> response data and call sendError. If no error occurs, then transfer the
> complete response data to the response object.
>
> -Spike
>
> ------Sample code --------
>
> StringWriter stringWriter = new StringWriter();
> PrintWriter writer = new PrintWriter(stringWriter);
>
> try{
> //Capture response data by writing to the StringWriter
> generateReponse(writer)
>
> //no error occurred, so transfer the completed response data to the
> response writer.
> writer.close();
> response.getWriter().println(stringWriter.toString());
> }
> catch(Throwable th){
> //error occurred - all data written to the stringWriter will be ignored.
> response.sendError(response.SC_INTERNAL_SERVER_ERROR, th.getMessage());
> }
>
> -----
> Spike Washburn
> IBM WebSphere Application Server
> Internet E-mail: [EMAIL PROTECTED]
>
> Srikanth Ranganathan <[EMAIL PROTECTED]> on 04/29/99 12:14:58 PM
>
> Please respond to "A mailing list for discussion about Sun Microsystem's
> Java Servlet API Technology."
> <[EMAIL PROTECTED]>
>
> To: [EMAIL PROTECTED]
> cc: (bcc: Donald Washburn/Raleigh/IBM)
> Subject: Re: An alternative to sendRedirect()
> orRequestDispatcher.forward()
>
> I am struggling with the same problem. I would like to clean out the
> print writer buffer, and substitute it with the contents of the error
> message.
>
> Does anybody have ideas as to deal with exceptions / error messages, when a
> partial
> response has been written into the printwriter out stream ?
>
> -Srikanth
>
> Neal Kaiser wrote:
>
> > I've realized one problem (and am still looking for a good solution). Let
> > me explain how a sample JSP flows:
> >
> > <Database Query is Done>
> > Things printed to PrintWriter
> > <Another Database Query is Done>
> > This printed
> > ...etc
> >
> > Now my <Database Query Done> tags can do a sendRedirect if there is an
> > error executing the SQL.
> >
> > So, say my first database query is done, then things are printed, then
> the
> > second query bombs. It will try to do a sendRedirect, which ofcourse
> won't
> > work because the servlet output stream has been written to. (Aside note,
> > this DID work with build 131 - but according to the spec, it probably
> > shouldn't have).
> >
> > As I see it, my options are to either:
> >
> > 1) Do all queries at the top of the JSP before any HTML is printed. The
> way
> > the JSPs are structured, this would not really be acceptable.
> >
> > 2) Somehow have my "out" PrintWriter really be a buffer. Then, when
> > everthing is done, print to the real output stream. I'm not sure how
> > possible this would be....
> >
> > Any other ideas?
> >
> > Thanks.
> >
> > At 09:25 AM 4/29/99 -0400, you wrote:
> > >I am using the latest JRun build (140) and much of my JSP functionality
> is
> > >failing. In many of my JSPs, I do some preliminary processing of a
> > >request, and if certan conditions are met, I forward the request to
> another
> > >JSP for processing.
> > >
> > >I do all this BEFORE anything is written to the PrintWriter (Servlet
> > >OutputSteam). This previously worked w/ build 131, but now doesn't.
> I've
> > >tried the RequestDispatcher.forward() also, no luck. In reading the
> spec,
> > >it says "You cannot use this method if the PrintWriter object has been
> > >obtained from the response..."
> > >
> > >Well, when JRun compiles a JSP to a JAVA file, one fo the first lines in
> > >the service() method is:
> > >
> > >PrintWriter out = new PrintWriter (new BufferedWriter( new
> > >OutputStreamWriter(Response.getOutputStream())),true)
> > >
> > >How can I get around this? I want to be able to forward requests, but
> > >cannot because getOutputStream has been called.
> > >
> > >Thanks,
> > >
> > >Neal Kaiser
> > >
> > >------------------------------------------------------------
> > >To unsubscribe, send email to [EMAIL PROTECTED]
> > >and include in the body of the message "unsubscribe jrun-development".
> > >
> > >
> >
> >
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