Subject RE: [Firebird-Java] Re: MD5 in VARCHAR
Author Robert DiFalco
Too bad the JDBC designers did not add methods to go along with
setString, getString, etc that take a character encoding argument.

I agree with removing the encoding. If for no other reason than it makes
#setBytes symetrical with #getBytes. Currently, when you write the MD5
with CHARACTER SET OCTETS, the bytes will go in as one value and come
out as another. For example, try something like this:

con.setAutoCommit( true );
con.executeUpdate( "CREATE TABLE Test(f_md5 VARCHAR(16) CHARACTER SET
OCTETS);" );

PreparedStatement ps =
con.prepareStatement( "INSERT INTO Test(f_md5) VALUES (?);" );

String s = "test string";
MessageDigest md = MessageDigest.getInstance( "MD5" );
byte data[] = md.digest( s );

s.setBytes( 1, data );

ps = con.prepareStatement( "SELECT * FROM Test WHERE f_md5 = ?;" );
ps.setBytes( 1, data );
ResultSet rs = ps.executeQuery();

byte got[] = rs.getBytes( 1 );

assertTrue( Arrays.equals( data, got ) ); // UH OH!

Odd, it finds the correct record, but the data retrieved is different
than what was put in and searched for!


-----Original Message-----
From: Roman Rokytskyy [mailto:rrokytskyy@...]
Sent: Wednesday, July 02, 2003 2:43 PM
Subject: [Firebird-Java] Re: MD5 in VARCHAR

> Oddly enough. It seems to require 28 OCTETS characters to hold 16
> bytes.
> Not sure how that match works out.
> ...
> OCTETS works but I think there is a problem with calculating the
> field length. If the field is 16 characters (the length of an MD5) I
> get a data truncation exception while 32 works. Maybe it splits each
> byte into a character of 128 bits instead of 256?

Hmmm... that's a "joke" of our encoder because your connection
encoding is UNICODE_FSS... I'm afraid there's no chance to fool it.
The only choice for you would be to modify line

field.sqldata = field.encodeString(value,javaEncoding);


field.sqldata = value;

in body of FBStringField.setBytes(int, byte[]) method.

Sorry.... I will modify version in HEAD branch, but if you use 1.0
release, you should fetch release version from the CVS.

Blas, should we consider this a bug or a feature? Currently
FBStringField.setBytes(byte[]) is used only in
FBStringField.setBinaryStream(InputStream) method. I see no point to
force encoing in that method. Also it is not consistent with
FBStringField.getBytes() method. What do you think?

Best regards,
Roman Rokytskyy

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