Fwd: Fwd: XML 1.1 -- Please stab me with a dull knife and trample my dead body

I retract that in its entirety!

You are 100% correct. Bytes in does not equal bytes out.

Wilf
(slightly humbled at this point)

---------- Forwarded message ----------
From: Canadian Wilf <[email protected]>
Date: Fri, Sep 7, 2012 at 3:47 PM
Subject: Re: [jdom-interest] Fwd: XML 1.1 -- Please stab me with a dull
knife and trample my dead body
To: Bjorn Roche <[email protected]>
Cc: [email protected]


Java strings are not zero terminated. In Java, you can do this just fine:

String string = new String(new byte[]{(byte) 0});
System.out.println("text is [" + string + "]");
System.out.println("bytes are: " + Arrays.toString(string.getBytes()));
System.out.println("chars are: " + Arrays.toString(string.toCharArray()));

and you get ...

text is [ ]
bytes are: [0]
chars are: [ ]

Whatever bytes you put into a String in java you always get out the same.
Only change would be if you add in one charset and extract in a different
one.

However, for binary data, like u said, Base 64 is best (it seems) since
that is the only way to ensure wysiwyg.

Wilf

On Fri, Sep 7, 2012 at 3:27 PM, Bjorn Roche <[email protected]> wrote:

>
> On Sep 7, 2012, at 4:43 PM, Canadian Wilf wrote:
>
> > I can do this:
> >
> > String random = new String(someRandomByte[])
>
> Let me address this by pointing out a degenerate case. Strings in java are
> terminated by the null char (er, I think. Wow, it's been a while since I
> learned this insanely basic thing). If your someRandomBytes contains two
> consecutive zero bytes (= a single zero char), then the string "random"
> will obviously not be what you wanted, because it will end early -- if you
> are lucky. Another example is if the "someRandomByte" ends in the first
> half of a unicode codepoint. What happens then? So, yes you can construct a
> string from a byte array like you did here but please don't! RTFM: "The
> behavior of this constructor when the given bytes are not valid in the
> default charset is unspecified." Unspecified. As in "it might delete your
> hard drive, log on to facebook and unfriend your wife." That's what
> unspecified means, so those bytes need to be "sanitized" too.
>
> If that's the kind of data you want to put in XML (raw, random-assed
> binary), use Base64!
>
> > However, the string cannot be passed to the Text of an XML Element since
> it may contain illegal characters (<= 0X20 ascii, vertical tab, etc.) This
> will fail:
> >
> > new Element("test").setText(random)
> >
> > XOM and JDOM both restrict the access and will throw
> IllegalDataException if one of the characters (0x--0xFFFF) is not in XML
> Unicode specs.
>
> First off, I think maybe you should read this because we are not talking
> about 0x0 to 0xFFFF: http://www.joelonsoftware.com/articles/Unicode.html
>
> Secondly, yes there are values that must be escaped in XML. For example <
> and > for obvious reasons, but the library does this for you. Then there
> are values you can't put into XML at all. These fall into other categories.
> "not valid in a string" (eg the NULL character usually used as a string
> terminator) is one. Yes, that's right, you can't put 0x00 in an XML string,
> 'cause you can't put it in a string! OMG! Stop the presses! I also find
> this annoying, and have been bitten by it (I think it was 0x17 or
> something), but that's life.
>
> I agree, however, it would be nice to have some clarity on exactly what's
> allowed.
>
> When in doubt, use Base64!
>
> Or create sub elements for the weird chars, just like html does for, say,
> newlines: <br />
>
>         bjorn
>
> -----------------------------
> Bjorn Roche
> http://www.xonami.com
> Audio Collaboration
> http://blog.bjornroche.com
>
>
>
>
>

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