[GitHub] [calcite-avatica] ambition119 edited a comment on issue #96: support from unix timestamp to string date

[GitBox]

ambition119 edited a comment on issue #96: support from unix timestamp to 
string date
URL: https://github.com/apache/calcite-avatica/pull/96#issuecomment-489890614
 
 
   > There are uses of default locale here. We can't have that. This code needs 
to behave identically in all locales.
   > 
   > In one or two places the comment says "unsigned int" when the result is 
clearly a signed long.
   > 
   > Methods that have a timezone argument must state very clearly, with 
examples, how the timezone is used. Are you converting to that timezone or from 
that timezone? So many times I expect a method to add 8 hours (to pacific) and 
it ends up subtracting 8 hours.
   
   Thank you for your suggestion, I  fix the problem caused by timezone, How 
about changing to the following?
   convert user input TimeZone.
   ```java
   /**
      * Convert unix timestamp (seconds since '1970-01-01 00:00:00' UTC) to 
use's TimeZone datetime string
      * in the given format.
      */
     public static String fromUnixTimestamp(long unixTimestamp, String format, 
TimeZone tz) {
       try {
         SimpleDateFormat formatter =
             new SimpleDateFormat(format, 
Locale.getDefault(Locale.Category.FORMAT));
         formatter.setTimeZone(UTC_ZONE);
         Date date = new Date(unixTimestamp * 1000);
         return formatter.format(date);
       } catch (Exception e) {
         return null;
       }
     }
   ```
   test like :
   ```
   assertThat(fromUnixTimestamp(-28800000,UTC_ZONE), is("1969-02-01 16:00:00"));
   assertThat(fromUnixTimestamp(1557134198, UTC_ZONE), is("2019-05-06 
09:16:38"));
   assertThat(fromUnixTimestamp(1557134198, TimeZone.getTimeZone("GMT+2")), 
is("2019-05-06 11:16:38"));
   assertThat(fromUnixTimestamp(1557134198, TimeZone.getTimeZone("GMT+8")), 
is("2019-05-06 17:16:38"));
   ```
   
   if convert to UTC TimeZone, also modify code like :
   ```java
   /**
      * Convert unix timestamp (seconds since '1970-01-01 00:00:00' UTC) to UTC 
datetime string
      * in the given format and TimeZone.
      */
     public static String fromUnixTimestamp(long unixTimestamp, String format, 
TimeZone tz) {
       try {
         SimpleDateFormat formatter =
             new SimpleDateFormat(format, 
Locale.getDefault(Locale.Category.FORMAT));
         formatter.setTimeZone(tz);
         Date date = new Date(unixTimestamp * 1000);
         Long targetTime = date.getTime() - tz.getRawOffset() + 
UTC_ZONE.getRawOffset();
         return formatter.format(new Date(targetTime));
       } catch (Exception e) {
         return null;
       }
     }
   ```
   test like：
   ```
   assertThat(fromUnixTimestamp(1557134198, UTC_ZONE), is("2019-05-06 
09:16:38"));
   assertThat(fromUnixTimestamp(1557134198, TimeZone.getTimeZone("GMT+2")), 
is("2019-05-06 09:16:38"));
   assertThat(fromUnixTimestamp(1557134198, TimeZone.getTimeZone("GMT+8")), 
is("2019-05-06 09:16:38"));
   ```
   
   
   

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