Accessing Databases Using JDBC - Java Programming: Comprehensive Concepts and Techniques - page 712

185 // Do NOT use with JDK 1.2.2 using JDBC-ODBC Bridge as

186 // SQL NULL data value is not handled correctly.

187 buf = rs.getBytes ( "pswd" ) ;

188 if ( buf != null )

189 {

190 System .out.println ( "Password Object = "

191 + ( pswdFromDB= ( Password ) deserializeObj ( buf ))) ;

192 System .out.println ( " AutoExpires = " + pswdFromDB.getAutoExpires ()) ;

193 System .out.println ( " Expiring now = " + pswdFromDB.isExpiring ()) ;

194 System .out.println ( " Remaining uses = "

195 + pswdFromDB.getRemainingUses () + "\n" ) ;

196 }

197 else

198 System .out.println ( "Password Object = NULL!" ) ;

199 }

200
201

rs = stmt.executeQuery ( "SELECT * FROM Stocks" ) ;

202 if ( !rs.next ())

203 System .out.println ( "Stocks table contains no records." ) ;

204 else

205 System .out.println ( "Stocks table still contains records!" ) ;

206
207 rs = stmt.executeQuery ( "SELECT * FROM UserStocks" ) ;

208 if ( !rs.next ())

209 System .out.println ( "UserStocks table contains no records." ) ;

210 else

211 System .out.println ( "UserStocks table still contains records!" ) ;

212
213 stmt.close () ; // closing Statement also closes ResultSet

214
215 } // end of main()

216
217 // Method to write object to byte array and then insert into prepared statement

218 public static byte [] serializeObj ( Object obj )

219 throws IOException

220 {

221 ByteArrayOutputStream baOStream = new ByteArrayOutputStream () ;

222 ObjectOutputStream objOStream = new ObjectOutputStream ( baOStream ) ;

223
224 objOStream.writeObject ( obj ) ; // object must be Serializable

225 objOStream.flush () ;

226 objOStream.close () ;

227 return baOStream.toByteArray () ; // returns stream as byte array

228 }

229
230 // Method to read bytes from result set into a byte array and then

231 // create an input stream and read the data into an object

232 public static Object deserializeObj ( byte [] buf )

233 throws IOException , ClassNotFoundException

234 {

235 Object obj = null ;

236
237

if ( buf != null )

238 {

239 ObjectInputStream objIStream =

240 new ObjectInputStream ( new ByteArrayInputStream ( buf )) ;

241
242 obj = objIStream.readObject () ; // throws IOException, ClassNotFoundException

243 }

244 return obj;

245 }

246 } // end of class

FIGURE 11-17