[jdom-interest] XMLOutputter newline and sockets

[Jason Hunter]

The default is for newlines not to be added, but the problem is SAX
doesn't report newlines outside the root element so that results in
output like:

<?xml version="1.0"><!-- comment --><root>
  <child/>
</root>

And people don't like that.  They say the file looked like this before
and I want it to stay that way:

<?xml version="1.0">
<!-- comment -->
<root>
  <child/>
</root>

So we add new lines outside the root element.  I agree it's less than
ideal, but with a few overrides you can get whatever you want.  What's
really needed is some tunable output feature that lets you specify which
general output style you want:

one line
best effort to round trip
best effort to beautify
  using two spaces, four spaces, tabs, etc

-jh-

Steve Upton wrote:
> 
> Hi All, well probably more Jason Hunter and Damian Van Dooren actually  :)
> 
> Let me set the scene and then I'll explain why....
> 
> I'm currently looking at creating a client server app that uses XML for its
> communication.
> So, client opens socket sends some commands, gets some responses and then
> socket is
> closed. As a newbie to Sockets and XML I've relied heavily on examples to
> learn this,
> so there may be a better way, but the way to do this seems to be:
> 
> - Server suns and listens on socket
> - Client runs and opens socket to server
> - Server accespts connection and fires off new thread wich does readLine()
> to get data
> - Client sends command and then does readLine() to get response
> ...
> ...
> - Process repeats until client is finished and terminates connection.
> 
> Ok, no problem so far, appart from the fact that what I'd like to do is :
> 
> Sender (could be client or server):
>     Creates a JDOM and then uses outputter.build() to generate the XML
> 
> Receiver:
>     String data = in.readLine()                      // Read complete XML
> from input stream
>     parser.build(new StringReader(data));    // Parse into JDOM
> 
>     ....                                                        // Walk tree
> to extract data.
> 
> Unfortuantely this is not possible because even if you cannot easily
> generate the XML in the first place
> as a single line, unless you omit the version header, or run it through a
> formatter to strip newlines before
> sending it. This to me seemed odd, as there appeared to be a bug in the
> XMLOutputter.build() method,
> a newline was being added after the version string, even though the doc says
> if no parameters are  passed to
> the XMLOutputter constructor newlines are suppressed in the output.
> 
> However, thought I'd better take a look at the archives, as a newbie -
> didn't want to ask a dumb question.
> I then found the conversation between you guys on this very subject:
> 
> ------------------------------------------------------------------------
> 
> From: VanDoorenD at cartierpartners.ca (Van Dooren, Damian)
> Date: Tue, 29 May 2001 12:53:12 -0400
> Subject: [jdom-interest] XMLOutputter surpressDeclaration
> 
> When using XMLOutputter and setting the supressDeclaration it still prints a
> newline. I doubt this is what is intended. I suggest it could be fixed one
> of two ways.
> 
> The first is within the output(Document doc, Writer out) method, we could
> check to see if the declaration is surpressed:
> 
> // Print new line after decl always, even if no other new lines
> // Helps the output look better and is semantically
> // inconsequential
> if (!suppressDeclaration) {
>     out.write(lineSeparator);
> }
> 
> Or IMHO the better place for it, the printDeclaration(Document doc, Writer
> out, String encoding) method. So remove it from output(Document doc, Writer
> out) and add it to printDeclaration(Document doc, Writer out, String
> encoding):
> 
>     /**
>      * <p>
>      * This will write the declaration to the given Writer.
>      *   Assumes XML version 1.0 since we don't directly know.
>      * </p>
>      *
>      * @param doc <code>Document</code> whose declaration to write.
>      * @param out <code>Writer</code> to write to.
>      * @param encoding The encoding to add to the declaration
>      */
>     protected void printDeclaration(Document doc,
>                                     Writer out,
>                                     String encoding) throws IOException {
> 
>         // Only print of declaration is not suppressed
>         if (!suppressDeclaration) {
>             // Assume 1.0 version
>             if (encoding.equals("UTF8")) {
>                 out.write("<?xml version=\"1.0\"");
>                 if (!omitEncoding) {
>                     out.write(" encoding=\"UTF-8\"");
>                 }
>                 out.write("?>");
>             }
>             else {
>                 out.write("<?xml version=\"1.0\"");
>                 if (!omitEncoding) {
>                     out.write(" encoding=\"" + encoding + "\"");
>                 }
>                 out.write("?>");
>             }
>   // Print new line after decl always, even if no other new
> lines
>   // Helps the output look better and is semantically
>   // inconsequential
>   out.write(lineSeparator);
>         }
>     }
> 
> ------------------------------------------------------------------------
> From: jhunter at collab.net (Jason Hunter)
> Date: Tue, 29 May 2001 18:48:46 -0700
> Subject: [jdom-interest] XMLOutputter surpressDeclaration
> 
> Fixed.  I choose door #2.  ;-)
> 
> -jh-
> ------------------------------------------------------------------------
> 
> Please, please can we have option #3 which is the same fix but with the
> newline supressed
> if setNewlines(false) .
> 
> Thanks
> 
> Steve
> 
> _____________________________________________________________
> Steve Upton
> Firebrand Software
> http://www.firebrandsoftware.com
> 
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