Programming Forums - View Single Post

ggilmour · Mar 26th, 2008, 12:58 AM

I'm working on a program that accesses an Interbase 5.x database using firebird/jaybird and the jdbc libraries. I've run into a problem with some compressed BLOB fields though.

I'm able to stream the BLOB into a text file, but have had no luck with decompressing the data.

Every attempt I've made to send the BLOB's InputStream through a FilteredStream (such as InflatorInputStream or ZipInputStream) has failed.

Does anyone have any experience with compressing/decompressing BLOB fields with java? Where am I going wrong?

Thanks,

(Toggle Plain Text)

//Get the blob (in Test_Data column) and store it in the Java BLOB object.
//Get an inputStream from the BLOB object so we can read it.
Blob importantData = testResults.getBlob("Test_Data");
InputStream blobStream = importantData.getBinaryStream();
	
//Create our output file
File myFile = new File("BlobOut.txt");
FileOutputStream fout = new FileOutputStream(myFile,true); 
	
// Create a ZipInputStream from the InputStream
ZipInputStream unZipBlob = new ZipInputStream(blobStream);
	
//Read from the BLOB's inputStream until it's empty.
	
while(unZipBlob.available() > 0)
//while(blobStream.available() > 0)
	
{
//write decompressed data to the output file
fout.write(unZipBlob.read());
		
//Write the raw compressed binary data. Appears to work  fine, but isn't readable!
//fout.write(blobStream.read());
}
	
		
//Close the file output stream.
fout.close();
}

Mar 26th, 2008, 12:58 AM	#1
ggilmour Newbie Join Date: Mar 2008 Posts: 2 Rep Power: 0	decoding compressed BLOBS I'm working on a program that accesses an Interbase 5.x database using firebird/jaybird and the jdbc libraries. I've run into a problem with some compressed BLOB fields though. I'm able to stream the BLOB into a text file, but have had no luck with decompressing the data. Every attempt I've made to send the BLOB's InputStream through a FilteredStream (such as InflatorInputStream or ZipInputStream) has failed. Does anyone have any experience with compressing/decompressing BLOB fields with java? Where am I going wrong? Thanks, (Toggle Plain Text) //Get the blob (in Test_Data column) and store it in the Java BLOB object. //Get an inputStream from the BLOB object so we can read it. Blob importantData = testResults.getBlob("Test_Data"); InputStream blobStream = importantData.getBinaryStream(); //Create our output file File myFile = new File("BlobOut.txt"); FileOutputStream fout = new FileOutputStream(myFile,true); // Create a ZipInputStream from the InputStream ZipInputStream unZipBlob = new ZipInputStream(blobStream); //Read from the BLOB's inputStream until it's empty. while(unZipBlob.available() > 0) //while(blobStream.available() > 0) { //write decompressed data to the output file fout.write(unZipBlob.read()); //Write the raw compressed binary data. Appears to work fine, but isn't readable! //fout.write(blobStream.read()); } //Close the file output stream. fout.close(); } //Get the blob (in Test_Data column) and store it in the Java BLOB object. //Get an inputStream from the BLOB object so we can read it. Blob importantData = testResults.getBlob("Test_Data"); InputStream blobStream = importantData.getBinaryStream(); //Create our output file File myFile = new File("BlobOut.txt"); FileOutputStream fout = new FileOutputStream(myFile,true); // Create a ZipInputStream from the InputStream ZipInputStream unZipBlob = new ZipInputStream(blobStream); //Read from the BLOB's inputStream until it's empty. while(unZipBlob.available() > 0) //while(blobStream.available() > 0) { //write decompressed data to the output file fout.write(unZipBlob.read()); //Write the raw compressed binary data. Appears to work fine, but isn't readable! //fout.write(blobStream.read()); } //Close the file output stream. fout.close(); }