[ARROW-7301][Java] Remove division in time conversion

Author: liyafan82

java/adapter/jdbc/src/main/java/org/apache/arrow/adapter/jdbc/consumer/DateConsumer.java

@@ -34,18 +34,13 @@
  */
 public class DateConsumer {
 
-  /**
-   * The number of milli-seconds in a day.
-   */
-  public static final long MILLIS_PER_DAY = TimeUnit.DAYS.toMillis(1);
-
   public static final int MAX_DAY;
 
   static {
     SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
     try {
       java.util.Date date = dateFormat.parse("9999-12-31");
-      MAX_DAY = (int) (date.getTime() / MILLIS_PER_DAY);
+      MAX_DAY = (int) TimeUnit.MILLISECONDS.toDays(date.getTime());
     } catch (ParseException e) {
       throw new IllegalArgumentException("Failed to parse max day", e);
     }
@@ -90,7 +85,7 @@ public void consume(ResultSet resultSet) throws SQLException {
       Date date = calendar == null ? resultSet.getDate(columnIndexInResultSet) :
           resultSet.getDate(columnIndexInResultSet, calendar);
       if (!resultSet.wasNull()) {
-        int day = (int) (date.getTime() / MILLIS_PER_DAY);
+        int day = (int) TimeUnit.MILLISECONDS.toDays(date.getTime());
         if (day < 0 || day > MAX_DAY) {
           throw new IllegalArgumentException("Day overflow: " + day);
         }
@@ -126,7 +121,7 @@ public NonNullableDateConsumer(DateDayVector vector, int index, Calendar calenda
     public void consume(ResultSet resultSet) throws SQLException {
       Date date = calendar == null ? resultSet.getDate(columnIndexInResultSet) :
           resultSet.getDate(columnIndexInResultSet, calendar);
-      int day = (int) (date.getTime() / MILLIS_PER_DAY);
+      int day = (int) TimeUnit.MILLISECONDS.toDays(date.getTime());
       if (day < 0 || day > MAX_DAY) {
         throw new IllegalArgumentException("Day overflow: " + day);
       }