Java TimeZone ++: mapping Calendar to Oracle Date or TimeStamp

/** * Table used: CREATE TABLE "DATEX" ("ID" NUMBER(3,0) NOT NULL ENABLE, "DT" DATE, "TMS" DATE NOT NULL ENABLE, "FACEVAL" VARCHAR2(50) NOT NULL ENABLE, CONSTRAINT "DATEX_PK" PRIMARY KEY ("ID") ENABLE ) * * @author spandurangi * */public class DBTimeStampReadWriteTest extends TestCase {TimeZone userTz = TimeZone.getTimeZone("IST");//Used for writing TO and reading FROM RDBMSstatic final Calendar networkCal = Calendar.getInstance(TimeZone.getTimeZone("EST"));String userEntered = "2009-01-31 01:00:01";/** * @throws Exception */public void testDirectWriteConvToSTDTz() throws Exception {SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");sdf.setTimeZone(userTz);Date userDate = sdf.parse(userEntered);System.out.println("========== DATABASE testDirectWriteConvToSTDTz TEST =================");Connection conn = null;try {conn = getConnection();PreparedStatement ps = conn.prepareStatement("Update datex set dt = ?, tms = ?, faceval =? where id=1");ps.setDate(1, new java.sql.Date(userDate.getTime()));ps.setTimestamp(2, new Timestamp(userDate.getTime()), networkCal);ps.setString(3, userEntered + " p/w " + sdf.getTimeZone().getID());ps.execute();Statement st = conn.createStatement();String SELECT_LATEST = "select * from datex where id = 1";Calendar ret = printRow(st.executeQuery(SELECT_LATEST));assertEquals(userDate,ret.getTime());} catch (Exception e) {e.printStackTrace();} finally {if (conn != null) {conn.close();}}}/** * Run this test seperately with Vm's TZ same after doing the first one * @throws Exception */public void testDirectReadConvToSTDTz() throws Exception {TimeZone.setDefault(TimeZone.getTimeZone("PST"));SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");// to compare the same value!!sdf.setTimeZone(userTz);Date userDate = sdf.parse(userEntered);System.out.println("========== DATABASE testDirectReadConvToSTDTz TEST =================");Connection conn = null;try {conn = getConnection();Statement st = conn.createStatement();String SELECT_LATEST = "select * from datex where id = 1";Calendar ret = printRow(st.executeQuery(SELECT_LATEST));assertEquals(userDate,ret.getTime());//Comparision may run on any vm!Calendar org = Calendar.getInstance();org.setTime(userDate);ret.setTimeZone(org.getTimeZone());System.out.println(decorate(org) + " == " + decorate(ret));assertEquals(decorate(org), decorate(ret));} catch (Exception e) {e.printStackTrace();} finally {if (conn != null) {conn.close();}}}private String decorate(Calendar cal) {FastDateFormat f = FastDateFormat.getInstance("EEE MMM dd HH:mm:ss z yyyy");return f.format(cal);}private Connection getConnection() throws Exception {Class.forName("oracle.jdbc.OracleDriver");String url = "jdbc:oracle:thin:@localhost:1521:xe";return DriverManager.getConnection(url, "sarath", "pass");}private Calendar printRow(ResultSet rs) throws Exception {rs.next();// JDBC driver reads by face value, loses date infojava.sql.Date sqlDate = rs.getDate("dt");Calendar cal = Calendar.getInstance();cal.setTime(sqlDate);System.out.println("Date Information");System.out.println(sqlDate + "::" + sqlDate.getTime() + " :: " + cal.getTime() + " :: " + cal.getTimeInMillis()+ " :: " + decorate(cal));// JDBC driver reads by face value, applies system tz, (mutates mill// secs) (WRONG WAY! binding to VM)Timestamp sqlTS = rs.getTimestamp("tms");cal = Calendar.getInstance();cal.setTime(sqlTS);System.out.println("Timestamp Information from db as it is");System.out.println(sqlTS + "::" + sqlDate.getTime() + " :: " + cal.getTime() + " :: " + cal.getTimeInMillis()+ " :: " + decorate(cal));// JDBC driver reads by face value, applies the supplied tz that is// supplied (mutates mill secs) (CORRECT! reads in same Tz)sqlTS = rs.getTimestamp("tms", networkCal);cal.setTime(sqlTS);System.out.println("Timestamp Information read with a different Cal (allTimesInTz)");System.out.println(sqlTS + "::" + sqlDate.getTime() + " :: " + cal.getTime() + " :: " + cal.getTimeInMillis()+ " :: " + decorate(cal));return cal;}}

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If you are using Hibernate, You could use a user type to get similar effect.

Adventurously, I used the TimeZone.setDefault method on non-production systems of an application involving Tomcat, WebLogic a couple of wars and one ear. So far, I have not observed any issues, Google doesnot have any pages that give any known situations either. If I come to know, I will update.