Android的短信的時間的顯示做的很精細，首先保存在短信數據庫mmssms.db中的短信時間都是Long型的數字，查詢動作結束，取到這個值之後，會做轉換，具體轉換的動作在MessageUtils.java的formatTimeStampString函數中完成；
時間轉換：
public static String formatTimeStampString(Context context, long when) {
return formatTimeStampString(context, when, false);
}
formatTimeStampString
public static String formatTimeStampString(Context context, long when, boolean fullFormat) {
Time then = new Time();
then.set(when);
Time now = new Time();
now.setToNow();
// Basic settings for formatDateTime() we want for all cases.
int format_flags = DateUtils.FORMAT_NO_NOON_MIDNIGHT |
DateUtils.FORMAT_ABBREV_ALL |
DateUtils.FORMAT_CAP_AMPM;
// If the message is from a different year, show the date and year.
if (then.year != now.year) {
format_flags |= DateUtils.FORMAT_SHOW_YEAR | DateUtils.FORMAT_SHOW_DATE;
} else if (then.yearDay != now.yearDay) {
// If it is from a different day than today, show only the date.
format_flags |= DateUtils.FORMAT_SHOW_DATE;
} else {
// Otherwise, if the message is from today, show the time.
format_flags |= DateUtils.FORMAT_SHOW_TIME;
}
// If the caller has asked for full details, make sure to show the date
// and time no matter what we've determined above (but still make showing
// the year only happen if it is a different year from today).
if (fullFormat) {
format_flags |= (DateUtils.FORMAT_SHOW_DATE | DateUtils.FORMAT_SHOW_TIME);
}
return DateUtils.formatDateTime(context, when, format_flags);
}
從第二個具體實現的函數可以看出來，Android是根據當前的時間為比較的依據來決定顯示的時間格式：
綜合考慮下來，這樣的顯示設計還是很合理的…
