For any JDBC: wrap Date inside String


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Thread: For any JDBC: wrap Date inside String

  1. #1
    Fabio Luis De Paoli Guest

    For any JDBC: wrap Date inside String

    Manisha, yesterday I had do build a new version of the class, capable of handling
    null Date objects. Here it goes, in case you or anyone else wants to use it:

    import java.util.Date;

    /**
    * This class is used to avoid date manipulation errors found in some Relational
    * Database Management Systems or their JDBC drivers. These limitations may
    * cause the date to be stored slightly different than it exists in the JVM,
    * sometimes with a small milisecond difference.<br>
    * <br>
    * The use of this class ensures that java.util.Date objects are able to be stored
    * in their natural format (a long number) in any RDBMS that supports String
    * columns (all of them).<br>
    * <br>
    * It also supports the storage of null Date objects.
    * @author Fabio Luis De Paoli
    * @since 2-Mar-2001
    * @version 1.1
    */
    public class DateSQLStringWrapper
    {
    private static final String zeroes = "0000000000000000000";

    public Date toDate(String aStr) {
    if (aStr.substring(0,5).equals("Anull")) return null;
    try {
    long tempLong;
    tempLong = (Long.valueOf(aStr.substring(1,20))).longValue();
    if (aStr.substring(0,1).equals("N")) tempLong = tempLong * (-1L);
    return new Date(tempLong);
    } catch (NumberFormatException nfe) {
    nfe.printStackTrace();
    throw new InternalError(nfe.getMessage());
    }
    }

    /**
    * This method will transform a Date into a 20 character long String
    * in the format:<br>
    * <br>
    * SNNNNNNNNNNNNNNNNNNN<br>
    * <br>
    * Where:<br>
    * <ul><li>S will contain P for positive, N for negative. This ensures correct
    * sorting of dates, because N comes before P. Zero is considered positive.
    * <li>NNNNNNNNNNNNNNNNNNN will contain zero padded, nineteen digit, string
    * translation of the Date's internal long number.
    * </ul>
    * For example, the Date "2001-Feb-19 0:00:00.000 GMT-3" will become the String
    * "P0000000982591200000".
    * <br>
    * Obs: if the supplied Date is null, the resulting string is "Anull", which will

    * sort before the smallest possible date.
    */
    public String toStr(Date aDate) {
    if (aDate == null) return "Anull";

    String tempOutput;
    String tempSignal;
    long tempLong = aDate.getTime();
    if (tempLong < 0) {
    tempLong = tempLong * (-1);
    tempSignal = "N";
    } else {
    tempSignal = "P";
    }
    tempOutput = zeroes + tempLong;
    int beginIndex = tempOutput.length() - 19;
    return (tempSignal + tempOutput.substring(beginIndex, beginIndex + 19));
    }
    }

    Fabio Luis De Paoli wrote:

    > mhadke@yahoo.com wrote:
    >
    > > i want to put java date(actually time from 1 jan, 1970) into sql database(sql
    > > 6.5 server). what should be type of that field in sql table? how to store
    > > java obj into it? does sql6.5 server support BIGINT that is given in JDBC
    > > book? do i have to use a driver other that jdbcdbc?
    > >
    > > -manisha

    >
    > You should use some type of "timestamp" column, and store the java.util.Date as a
    > java.sql.Date or java.sql.Timestamp object.
    >
    > However WATCH OUT for:
    > - buggy jdbcs that incorrectly add one or two miliseconds to your Date during the
    > insert or the read operation
    > - buggy jdbcs that use the default Timezone to translate your Date's value to
    > GMT+0 when storing data, but not when reading it (ARGH... happened to me)
    >
    > I grew tired of playing with databases and JDBCs and decided to wrap the Date
    > into a String, using the class below. Feel free to use it.


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