Re: PrintWriter as blob with mysql
belletti.stefano@email.it wrote:
probably it's a poor design of my application, however ...
in a class i [sic] create
PrintWriter pw = new PrintWriter( new
BufferedOutputStream(socket.getOutputStream(), 1024), true);
then i "insert" it in a blob field in a mysql table
the insertion seems ok, the field contains something
like:"java.io.PrintWriter@c2ff5"
in another class i read that blob field (and try to use it as a
PrintWriter)
Blob writerletto = rs.getBlob("blobfield");
but it contains:"com.mysql.jdbc.Blob@1adc30" !!
and i'm not able to use it as a PrintWriter.
I've tried something like
pwTo=new PrintWriter(writerletto);
but there is not such constructor.
am idefinetely on the WRONG road ?
Yes.
You don't really show us your code, so some parts of our responses must be
speculative, however the field contents after you "insert" your PrintWriter
show that it contains a string, not a Writer at all.
Except for a caveat I'm about to mention.
Blobs are meant to receive binary data, clobs take character data. They can
take an InputStream or Reader, respectively, from which to accept their data.
It is meaningless to store an OutputStream or Writer to a database.
A PrintWriter is not a serializable object. If you somehow were able to store
it as more than just a string, it would have lost all its context that make it
effective as a PrintWriter.
OTOH, your report of what the blob "contains" upon reading it indicates that
you have not even stored the String "java.io.PrintWriter@c2ff5" as you report.
It could be that your way of determining the contents is actually returning
the default toString() of the PrintWriter or Blob object of interest, not the
actual contents of the database field. You should check the database (which
one is it, BTW?) with its interactive query tool (e.g., "psql" for Postgres).
Without your source it's not really possible to answer your question. How
about you provide a simplified complete example of your problem: an SSCCE?
<http://www.physci.org/codes/sscce.html>
--
Lew