/**
* Obtains streams from the Clob and makes sure we can always read the last char in the Clob.
*
* <p>See DERBY-4060.
*
* @param id id of the Clob to use
* @param length the length of the Clob
* @param alphabet the alphabet used to create the content
* @throws IOException if reading from a stream fails
* @throws SQLException if something goes wrong
*/
private void getCharacterStreamLongLastChar(int id, int length, CharAlphabet alphabet)
throws IOException, SQLException {
// Get last char from the source stream.
Reader cmpReader = new LoopingAlphabetReader(length, alphabet);
cmpReader.skip(length - 1);
char srcLastChar = (char) cmpReader.read();
assertTrue(cmpReader.read() == -1);
PreparedStatement ps = prepareStatement("select CLOBDATA from BLOBCLOB where ID=?");
ps.setInt(1, id);
// Read everything first.
int charsToRead = length;
ResultSet rs = ps.executeQuery();
rs.next();
Reader reader = rs.getClob(1).getCharacterStream(length - charsToRead + 1, charsToRead);
// Drain the stream, and make sure we are able to read the last char.
char lastCharRead = getLastCharInStream(reader, charsToRead);
assertEquals(srcLastChar, lastCharRead);
reader.close();
rs.close();
// Read a portion of the stream.
charsToRead = length / 4;
rs = ps.executeQuery();
rs.next();
reader = rs.getClob(1).getCharacterStream(length - charsToRead + 1, charsToRead);
lastCharRead = getLastCharInStream(reader, charsToRead);
assertEquals(srcLastChar, lastCharRead);
reader.close();
rs.close();
// Read a very small portion of the stream.
charsToRead = 1;
rs = ps.executeQuery();
rs.next();
reader = rs.getClob(1).getCharacterStream(length - charsToRead + 1, charsToRead);
lastCharRead = getLastCharInStream(reader, charsToRead);
assertEquals(srcLastChar, lastCharRead);
reader.close();
rs.close();
}
private StringBuffer getDataFromReader(Reader br) {
StringBuffer xferData = null;
char[] buf = new char[513];
int charsRead;
try {
do {
charsRead = br.read(buf, 0, 512);
if (charsRead != -1) {
JConfig.log().logVerboseDebug("Read: " + charsRead + " characters.");
if (xferData == null) {
xferData = new StringBuffer();
}
xferData.append(buf, 0, charsRead);
}
} while (charsRead != -1);
br.close();
} catch (IOException e) {
JConfig.log().logDebug("Caught an IO Exception trying to read the drag/drop data!");
return null;
}
return xferData;
}
public void close() throws IOException {
reader.close();
}