Question

My little test-program is writing a serialized object into a mysql database, then retrieving it again, casting it to an object, then running it’s toString(). I’m trying to get the whole idea about Blobs on databases. (The object is a goat, that has a name, age and sex) My problem is that when I insert it into the database, it only sends the first byte, and not the rest.

First I write the object:

    String query = "INSERT INTO goats(goat) VALUES (goat = ?)";
    PreparedStatement pstmt = con.prepareStatement(query);
    ByteArrayOutputStream b = new ByteArrayOutputStream();
    ObjectOutputStream out = new ObjectOutputStream(b);
    out.writeObject(goat);
    byte[] dataAsByteArray = b.toByteArray();
    pstmt.setBinaryStream(1 , new ByteArrayInputStream(dataAsByteArray), dataAsByteArray.length);

Then I retrieve it again:

    Statement stmt = con.createStatement();
    ResultSet rs = stmt.executeQuery("SELECT goat FROM goats");
    rs.next();
    Blob blob = rs.getBlob(1);
    byte[] bytes = blob.getBytes(1, (int) blob.length()); 
    ByteArrayInputStream bis = new ByteArrayInputStream(bytes);
    ObjectInputStream ois = new ObjectInputStream (bis);

Thanks

Answer 1

out.close();

Seems to be missing.

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The answer seems to be that goat=? is a boolean comparison yielding 0 or 1; a typo.

VALUES(goat = ?) should be VALUES(?).