Thanks, it all helps :-), I am getting there and hopefully soon be able
to properly state my problems.
My Base64 encoder has methods to encode the image byte[] to a Stirng and
then decode the String back to a byte[] for my io. It has been working
well so far.
My main concern is with the text I am encoding and decoding. If I set
the OutputFormat as follows will I be able to construct my DOM without
encoding my text strings as they will automatically be encoded in the
serialization process?
OutputFormat of = new OutputFormat("XML", " ISO-8859-1", true);
XMLSerializer ser = new XMLSerializer(System.out, of);
Then when I parse the InputStream that contains the serialized DOM will
all the text nodes that I read automatically be decoded when I
getNodeValue()?
Many thanks,
Greg
-----Original Message-----
From: Constantine Georges [mailto:[EMAIL PROTECTED]
Sent: Thursday, April 17, 2003 4:42 PM
To: [EMAIL PROTECTED]
Subject: Re: General tips help, NEWBIE?
Greg:
I don't know how familiar you are with the Base64 encoding, but,
basically,
here's the text that would come out:
Table 1: The Base64 Alphabet
Value Encoding Value Encoding Value Encoding Value Encoding
0 A 17 R 34 i 51 z
1 B 18 S 35 j 52 0
2 C 19 T 36 k 53 1
3 D 20 U 37 l 54 2
4 E 21 V 38 m 55 3
5 F 22 W 39 n 56 4
6 G 23 X 40 o 57 5
7 H 24 Y 41 p 58 6
8 I 25 Z 42 q 59 7
9 J 26 a 43 r 60 8
10 K 27 b 44 s 61 9
11 L 28 c 45 t 62 +
12 M 29 d 46 u 63 /
13 N 30 e 47 v
14 O 31 f 48 w (pad) =
15 P 32 g 49 x
16 Q 33 h 50 y
The concept behind Base64 is using 4 6-bit characters to encode 3 actual
bytes. Anyway, as you can see, there are no XML special characters in
the
Base64 vocabulary (<, >, or &), so the entire image could just be added
as
the value of any tag or attribute.
I think the main issue, then, is in your Base64 encoder and its
interface.
Does it return a byte[ ], or does it return a String? If it returns a
byte
[ ], you're going to have to be careful since Java's characters are 16
bits, and not 8 (i.e., you can't just call String(imgbuf)). Setting an
Element or Attribute value, since that interface uses Java String
objects,
becomes a question of taking the Base64 and widening the 8 bit bytes to
16
bit chars. Really, it's simple to do -- a brute-force implementation
would
be to construct a StringBuffer, iterate across the array, and just
strbuf.append((char) imgbuf[i]). Then, as you're building the DOM, set
some element or attribute's value to the String value of the buffer:
StringBuffer strbuf = new StringBuffer();
// dump the image into the buffer here...
Element img = doc.createElement("image");
Text value = doc.createTextNode(strbuf.toString());
img.appendChild(value);
doc.appendChild(img);
And, when you go to get your original image back again, just down-cast
the
characters in the string to bytes and feed the byte array to the Base64
decoder.
If, of course, your Base64 decoder works with Java Strings natively,
then
this is a non-issue.
>From my experience, I would say be careful with XMLSerializer -- it cuts
lines off if they are too long unless you specify that it should
preserve
space in the output format object. Also, if you're working with
namespaces
at all, it can put some junk in your serialized file in terms of
namespace
prefixes. In terms of initially setting it up, here's what I always do:
OutputFormat of = new OutputFormat("XML", "UTF-8", true);
XMLSerializer ser = new XMLSerializer(System.out, of);
Does any of this help?
C
To: "Xerces User
Mail list" <[EMAIL PROTECTED]>
"Greg Hess" cc: (bcc:
Constantine Georges/Towers Perrin)
<[EMAIL PROTECTED] Subject: General tips
help, NEWBIE?
s.com>
04/17/2003 03:45
PM
Please respond to
xerces-j-user
Hi All,
I would greatly appreciate any help that you could provide on helping me
complete my task. I am new to Xerces and XML parsing and having
difficulty
understanding how I should be implementing this functionality.
I have a web form that allows a user to enter text(may contain reserved
characters)/image upload used to populate a remote web page. My
Servlet(Action) as I am using Struts, takes the text and image byte[]
and
creates a XML document containing the data. As I build the DOM I use a
Base64 encoding tool to encode my text and image byte[].
I then send the XML DOM to a remote Servlet to be handled. I do this via
HTTP POST using the XMLSerializer to write the DOM to the Servlets
OutputStream
XMLSerializer serializer = new XMLSerializer(os, null);
serializer.serialize(doc);
I have been looking at the OutputFormat and wondering if I could just
set
the encoding of the OutputFormat and my text nodes would be encoded by
the
XMLSerializer. If so could I still use the Base64 encoder to encode my
image byte[]?
Any help much appreciated,
Greg
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