Hi Robert,

If I remember correctly, if you don't do this it reads the entire blob into
a memory buffer. Multi-megabyte blobs can cause out of memory errors. If
your system has enough memory you can increase the memory Java allocates,
but if you distribute your program you cannot guarantee that this will be
done.


Rick

----- Original Message -----

> In the FAQ.[txt|html], there is the following code. I'm pretty sure I
> have no idea why the advice is given to use a BufferedInputStream. First
> of all because we are reading into a byte array.
>
> Second, I'm not sure why one should "ever" use a BufferedInputStream
> since it appears to me that the result of #getBinaryStream is already
> buffered.
>
> What am I missing? Here's the code from the FAQ.
>
> try {
>
> // The ByteArrayOutputStream buffers all bytes written to it
> // until we call getBytes() which returns to us an array of bytes:
> ByteArrayOutputStream baos = new ByteArrayOutputStream(1024);
>
> // Create an input stream from the BLOB column. By default,
> rs.getBinaryStream()
> // returns a vanilla InputStream instance. We override this for
> efficiency
> // but you don't have to:
> BufferedInputStream bis = new BufferedInputStream(
> rs.getBinaryStream("fieldblob") );
>
> // A temporary buffer for the byte data:
> byte bindata[1024];
>
> // Used to return how many bytes are read with each read() of the
> input stream:
> int bytesread = 0;
>
> // Make sure its not a NULL value in the column:
> if ( !rs.wasNull() ) {
> if ( (bytesread = bis.read(bindata,0,bindata.length)) != -1 ) {
> // Write out 'bytesread' bytes to the writer instance:
> baos.write(bindata,0,bytesread);
> } else {
> // When the read() method returns -1 we've hit the end of the
> stream,
> // so now we can get our bytes out of the writer object:
> returndata = baos.getBytes();
> }
> }
>
> // Close the binary input stream:
> bis.close();
> } catch ( IOException ioe ) {
> System.err.println("Problem retrieving binary data: " + ioe);
> } catch ( ClassNotFoundException cnfe ) {
> System.err.println("Problem retrieving binary data: " + cnfe);
> }
>
>
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