Java(Android) 将 SQLite 日期转换为 "x days ago"

Question

我有:

String date = "2010-10-9 12:00:00";

我想解析该字符串，然后从当前日期/时间中减去该日期/时间，以便我可以输出类似于“2 天前”的字符串。

Answer 1

这是我正在使用的辅助类，它扩展了 Android 的标准 DateUtils。它有一个高级逻辑，对于今天的时间戳，它会显示秒或分钟或小时，而对于其他时间戳，它会显示日期。

您可以在 getTimeDiffString 方法中根据需要调整逻辑。作为参数，您将解析您在上述代码中获取的 Date date = formatter.parse(dateString); 的时间戳。

代码逻辑符合您从 Facebook 或 Twitter 了解到的“时间戳显示”。

public class DateTimeUtils extends DateUtils {

     private static String mTimestampLabelYesterday;
     private static String mTimestampLabelToday;
     private static String mTimestampLabelJustNow;
     private static String mTimestampLabelMinutesAgo;
     private static String mTimestampLabelHoursAgo;
     private static String mTimestampLabelHourAgo;

    /**
     * Singleton contructor, needed to get access to the application context & strings for i18n
     * @param context Context
     * @return DateTimeUtils singleton instanec
     * @throws Exception
     */
     public static DateTimeUtils getInstance(Context context) {
         mCtx = context;
         if (instance == null) {
             instance = new DateTimeUtils();
             mTimestampLabelYesterday = context.getResources().getString(R.string.WidgetProvider_timestamp_yesterday);
             mTimestampLabelToday = context.getResources().getString(R.string.WidgetProvider_timestamp_today);
             mTimestampLabelJustNow = context.getResources().getString(R.string.WidgetProvider_timestamp_just_now);
             mTimestampLabelMinutesAgo = context.getResources().getString(R.string.WidgetProvider_timestamp_minutes_ago);
             mTimestampLabelHoursAgo = context.getResources().getString(R.string.WidgetProvider_timestamp_hours_ago);
             mTimestampLabelHourAgo = context.getResources().getString(R.string.WidgetProvider_timestamp_hour_ago);
         }
         return instance;
     }

    /**
     * Checks if the given date is yesterday.
     *
     * @param date - Date to check.
     * @return TRUE if the date is yesterday, FALSE otherwise.
     */
    public static boolean isYesterday(long date) {

        final Calendar currentDate = Calendar.getInstance();
        currentDate.setTimeInMillis(date);

        final Calendar yesterdayDate = Calendar.getInstance();
        yesterdayDate.add(Calendar.DATE, -1);

        return yesterdayDate.get(Calendar.YEAR) == currentDate.get(Calendar.YEAR) && yesterdayDate.get(Calendar.DAY_OF_YEAR) == currentDate.get(Calendar.DAY_OF_YEAR);
    }

    public static String[] weekdays = new DateFormatSymbols().getWeekdays(); // get day names
    public static final long millisInADay = 1000 * 60 * 60 * 24;


    ...

    /**
     * Displays a user-friendly date difference string
     * @param timedate Timestamp to format as date difference from now
     * @return Friendly-formatted date diff string
     */
    public String getTimeDiffString(long timedate) {
        Calendar startDateTime = Calendar.getInstance();
        Calendar endDateTime = Calendar.getInstance();
        endDateTime.setTimeInMillis(timedate);
        long milliseconds1 = startDateTime.getTimeInMillis();
        long milliseconds2 = endDateTime.getTimeInMillis();
        long diff = milliseconds1 - milliseconds2;

        long hours = diff / (60 * 60 * 1000);
        long minutes = diff / (60 * 1000);
        minutes = minutes - 60 * hours;
        long seconds = diff / (1000);

        boolean isToday = DateTimeUtils.isToday(timedate);
        boolean isYesterday = DateTimeUtils.isYesterday(timedate);

        if (hours > 0 && hours < 12) {
            return hours==1? String.format(mTimestampLabelHourAgo,hours) : String.format(mTimestampLabelHoursAgo,hours);
        } else if (hours <= 0) {
            if (minutes > 0)
                return String.format(mTimestampLabelMinutesAgo,minutes);
            else {
                return mTimestampLabelJustNow;
            }
        } else if (isToday) {
            return mTimestampLabelToday;
        } else if (isYesterday) {
            return mTimestampLabelYesterday;
        } else if (startDateTime.getTimeInMillis() - timedate < millisInADay * 6) {
            return weekdays[endDateTime.get(Calendar.DAY_OF_WEEK)];
        } else {
            return formatDateTime(mCtx, timedate, DateUtils.FORMAT_NUMERIC_DATE);
        }
    }

} 

而 strings.xml 包含:

<string name="WidgetProvider_timestamp_today">Today</string>
<string name="WidgetProvider_timestamp_yesterday">Yesterday</string>
<string name="WidgetProvider_timestamp_hour_ago">%s hour ago</string>
<string name="WidgetProvider_timestamp_hours_ago">%s hours ago</string>
<string name="WidgetProvider_timestamp_minutes_ago">%s minutes ago</string>
<string name="WidgetProvider_timestamp_just_now">Just now</string>