从数据库重读取图片的问题

Question

FileOutputStream fout = new FileOutputStream("d:\\bb.jpg");
                    DataOutputStream dout = new DataOutputStream(fout);
                    strsql = "select userimg from mypic where userid='aa'";
                    ResultSet rs = runMain.stmt.executeQuery(strsql);
                    rs.next();
                    InputStream fin = rs.getBinaryStream(1);
                    int size = fin.available();  //抛异常
                    byte bb[] = new byte[size];
                    fin.read(bb);
                    dout.write(bb);
                    fin.close();
为什么会抛异常呢，请教大家啊，想了好久                    fout.close();
                    dout.close();