Java(Android)将SQLite日期转换为“x天前”

Question

我有:

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

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

- Paul

Answer 1

这是我正在使用的助手类，它扩展了Android的标准DateUtils。它具有高级逻辑，对于今天的时间戳，它将显示秒、分钟或小时，而对于其他时间戳，它将显示日期。

您可以在 getTimeDiffString 方法中根据需要调整逻辑。作为参数，您将解析上面代码中获取的 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);
        }
    }

} 

字符串.xml文件中包含以下内容：

<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>

- Mathias Conradt

---

你需要导入以下几个类：import java.text.DateFormatSymbols; import java.util.Calendar; import android.content.Context; import android.text.format.DateUtils; 并在你的类中声明两个变量：private static Context mCtx; private static DateTimeUtils instance; - happyhardik

Answer 2

尝试这个：

    long currentTimeMillis = System.currentTimeMillis();
    CharSequence string = DateUtils.getRelativeTimeSpanString(currentTimeMillis, currentTimeMillis + DateUtils.MINUTE_IN_MILLIS * 5, 0, DateUtils.FORMAT_ABBREV_ALL);

- Vladimir

Answer 3

也许有更好的方法来实现这一点，但这个方法可以工作。

String dateString = "2010-10-9 12:00:00";
String daysAgo = null;
// How many milliseconds in 1 day
final long DAY_IN_MILLIS = 86400000;
// The current timestamp in milliseconds
long now = System.currentTimeMillis();
// The format of your date string assuming the 1 am would read 01:00, not 1:00
// and Jan 1, 2010 would read 2010-1-1, not 2010-01-01
final DateFormat formatter = new SimpleDateFormat("yyyy-M-d hh:mm:ss");
// The calendar instance which adds a locale to the date
final Calendar cal = Calendar.getInstance();
try {
    // Parse the date string to return a Date object
    Date date = formatter.parse(dateString);
    // Set the calendar with our date object
    cal.setTime(date);
    // Get the millis timestamp of your date string
    long then = cal.getTimeInMillis();
    // Calculate the difference
    long difference = now - then;
    int ago = 0;
    // If the difference is greater than one day
    if (difference >= DAY_IN_MILLIS) {
        // Find the product
        ago = (int) (difference / DAY_IN_MILLIS);
        // Format your new string
            // You may want to check if(ago>1) here
        daysAgo = String.format("%d day(s) ago", ago);
    }
    // Write the result to Logcat
    Log.d(TAG, daysAgo);

} catch (ParseException e) {
    Log.e(TAG, e.getLocalizedMessage());
}   

- Paul Burke

Answer 4

将其转换为日期。获取当前日期时间。计算差异。

- Alex Volovoy

---

是的，那正是我想做的。现在如果有人能够友善地向我展示如何实现它就太好了。 - Paul