ok, I fixed my issue by making sure that the total chunk I read in is
equaled the total size of the file. Using Bytes.getArray(bytebuff) to
write out and my total file read and write is now the same size.
Thanks,
Noah
On Monday, September 22, 2014 at 6:50:51 AM UTC-4, Carlos Scheidecker wrote:
>
> Hello all,
>
> I can successfully read a file to a ByteBuffer and then write to a
> Cassandra blob column. However, when I retrieve the value of the column,
> the size of the ByteBuffer retrieved is bigger than the original ByteBuffer
> where the file was read from. Writing to the disk, corrupts the image.
>
> So I read a JPG:
>
> private ByteBuffer readFile(String filename) {
> FileInputStream fIn;
> FileChannel fChan;
> long fSize;
> ByteBuffer mBuf;
> try {
> fIn = new FileInputStream(filename);
> fChan = fIn.getChannel();
> fSize = fChan.size();
> mBuf = ByteBuffer.allocate((int) fSize);
> fChan.read(mBuf);
> //mBuf.rewind();
> fChan.close();
> fIn.close();
> //mBuf.clear();
> return mBuf;
> } catch (IOException exc) {
> System.out.println("I/O Error: " + exc.getMessage());
> System.exit(1);
> }
> return null;
> }
>
> So I run readFile and save it to the contents column down which is a blob.
>
> ByteBuffer file1 = readFile(filename);
>
> Then I retrieve the object I call Attachment which has the following
> definition from the table:
>
> CREATE TABLE attachment (
> attachmentid timeuuid,
> attachmentname varchar,
> mimecontenttype varchar,
> contents blob,
> PRIMARY KEY(attachmentid)
> );
>
> The ByteBuffer is saved under the contents column.
>
> When I retrieve that ByteBuffer file2 = readAttachment.getContents();
>
> I notice that file1 is java.nio.HeapByteBuffer[pos=99801 lim=99801
> cap=99801] and file2 that is retrieved is java.nio.HeapByteBuffer[pos=0
> lim=99937 cap=99937]
>
> As you can see the original size was 99801 how it was save, and is now
> 99937 so when I get that retrieved ByteBuffer which I assign to file2 and
> write it to disk, I have a JPG that I cannot read because has some metadata
> in from of it.
>
> I am attaching the original JPG, 1.jpg and 1_retrieve.jpg which is the one
> with size 99937.
>
> So there is a difference of 99937-99801=136 between them.
>
> Therefore, taking the retrieved one and saving to a physical file will
> prevent the system to display the JPG as it will error as: "Error
> interpreting JPEG image file (Not a JPEG file: starts with 0x82 0x00)"
>
> Why is that the blob retrieved from the column bigger than the one I have
> saved initially to the same column? Is there an offset that I need to deal
> with? If I call buffer.arrayOffset() on the retrieved ByteBuffer the value
> of the offset is 0.
>
> Here's the function I use to write file2 to the physical file
> 1_retrieved.jpg:
>
> private void writeFile(ByteBuffer buffer, String destname) {
> try (RandomAccessFile out = new RandomAccessFile(destname, "rw")) {
> //
> byte[] data = new byte[buffer.limit()];
> //buffer.flip();
> buffer.get(data);
> out.write(data);
> out.close();
> } catch (IOException e) {
> // TODO Auto-generated catch block
> e.printStackTrace();
> }
> }
>
> Thanks.
>
