Java - Zipping BLOB

Question

I have a table annotations (ann_annotation BLOB) which is becoming too large. That's why we opted for zipping the contents. For this purpose I have created (on Oracle 10i, JVM 1.5) 2 java-methods as follows:
CREATE OR REPLACE JAVA SOURCE NAMED "ZipHandler" AS
import java.lang.*;
import java.sql.*;
import oracle.sql.*;
import java.io.*;
import java.util.zip.*;
import oracle.jdbc.*;
public static BLOB Decompre(BLOB inBlob, Connection conn) throws Exception
BLOB outBlob = BLOB.createTemporary(conn, false, BLOB.DURATION_SESSION);
byte[] input = inBlob.getBytes();
byte[] output = new byte[103090];
int decompressedDataLength = 0;
Inflater decompressor = new Inflater(true);
decompressor.setInput(input);
decompressedDataLength = decompressor.inflate(output);
decompressor.end();
OutputStream outstream = outBlob.getBinaryOutputStream();
outstream.write(output,0, decompressedDataLength);
outstream.close();
return outBlob;     
public static BLOB Compre(BLOB inBlob, Connection conn) throws Exception
BLOB outBlob = BLOB.createTemporary(conn, false, BLOB.DURATION_SESSION);
byte[] input = inBlob.getBytes();
byte[] output = new byte[10000000];
Deflater compressor = new Deflater(-1,true);
compressor.setInput(input);
compressor.finish();
int compressedDataLength = compressor.deflate(output, 0, output.length);
OutputStream outstream = outBlob.getBinaryOutputStream();
outstream.write(output,0, compressedDataLength);
outstream.flush();
outstream.close();
return outBlob;
public static BLOB CompDecomp(BLOB inBlob,String test) throws Exception
Connection conn = inBlob.getJavaSqlConnection();
Statement stmt = conn.createStatement();
BLOB blob = null;
ResultSet rset = stmt.executeQuery("SELECT ann_annotation FROM annotations WHERE ann_id="+test);
while(rset.next()){
blob = Decompre(Compre(((OracleResultSet)rset).getBLOB("ann_annotation"), conn), conn);
return blob;
The 3rd method CompDecomp is just there to test if the resulting Zipped-Unzipped BLOBe is the same as the original. This is not the case. My original file = > 100000 bytes, the Zipped one is 59 (when I zip it with Winzip, the file is still > 100000, so the error relies somewhere in saving the result into the BLOB), and Unzipped it is 84 bytes.
Strangly the following code gives back the original BLOB:
public static BLOB CompDecomp(BLOB inBlob, String test) throws Exception
BLOB ultoutBlob = BLOB.createTemporary(conn, false, BLOB.DURATION_SESSION);
byte[] input = inBlob.getBytes();
byte[] output = new byte[10000000];
Deflater compressor = new Deflater();
compressor.setInput(input);
compressor.finish();
int compressedDataLength = compressor.deflate(output);
byte[] input2 = output; // which is directly a byte, not a BLOB
byte[] output2 = new byte[10000000];
int decompressedDataLength = 0;
Inflater decompressor = new Inflater();
decompressor.setInput(input2);
decompressedDataLength = decompressor.inflate(output2);
decompressor.end();
OutputStream outstream2 = ultoutBlob.getBinaryOutputStream();
outstream2.write(output2);
outstream2.close();
return ultoutBlob;
The only difference I see, is that I do not save the intermediate Zipped content into a BLOB.
Edited by: user10692128 on 8-dec-2008 6:19
Edited by: user10692128 on 8-dec-2008 6:20

Answer 1

Thanks Marcelo, this helped a lot.
I changed the code as follows:
public static BLOB Decompress(BLOB inBlob, Connection conn) throws Exception
BLOB outBlob = BLOB.createTemporary(conn, false, BLOB.DURATION_SESSION);
OutputStream outstream = outBlob.getBinaryOutputStream();
InputStream instream = inBlob.getBinaryStream();
byte[] input = new byte[BLOB.MAX_CHUNK_SIZE];
byte[] output = new byte[BLOB.MAX_CHUNK_SIZE];
Inflater decompressor = new Inflater(true);
while (true) { // read and deflate the data     
// Fill the input array.
int numRead = instream.read(input);
if (numRead == -1) { // end of stream
// Inflate any data that remains in the input buffer.
while (!decompressor.finished()) {
int decompressedDataLength = decompressor.inflate(output, 0, output.length);
if (decompressedDataLength > 0) {
outstream.write(output,0, decompressedDataLength);
} // end if
} // end while
break; // Exit while loop.
} // end if
else {  // Inflate the input.
decompressor.setInput(input, 0, numRead);
while (!decompressor.needsInput()) {
int decompressedDataLength = decompressor.inflate(output, 0, output.length);
if (decompressedDataLength > 0) {
outstream.write(output, 0, decompressedDataLength);
} // end if
} // end while
} // end else
} // end while
instream.close();
outstream.flush();
outstream.close();
return outBlob;     
public static BLOB Compress(BLOB inBlob, Connection conn) throws Exception
BLOB outBlob = BLOB.createTemporary(conn, false, BLOB.DURATION_SESSION);
OutputStream outstream = outBlob.getBinaryOutputStream();
InputStream instream = inBlob.getBinaryStream();
byte[] input = new byte[BLOB.MAX_CHUNK_SIZE];
byte[] output = new byte[BLOB.MAX_CHUNK_SIZE];
Deflater compressor = new Deflater();
while (true) { // read and deflate the data     
// Fill the input array.
int numRead = instream.read(input);
if (numRead == -1) { // end of stream
// Deflate any data that remains in the input buffer.
compressor.finish();
while (!compressor.finished()) {
int compressedDataLength = compressor.deflate(output, 0, output.length);
if (compressedDataLength > 0) {
outstream.write(output,0, compressedDataLength);
} // end if
} // end while
break; // Exit while loop.
} // end if
else {  // Deflate the input.
compressor.setInput(input, 0, numRead);
while (!compressor.needsInput()) {
int compressedDataLength = compressor.deflate(output, 0, output.length);
if (compressedDataLength > 0) {
outstream.write(output, 0, compressedDataLength);
} // end if
} // end while
} // end else
} // end while
instream.close();
outstream.flush();
outstream.close();
compressor.reset();
return outBlob;
It still does not work (I seem to lose some bytes somewhere in the zipping process), but I'm getting closer. ;-)