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，以便输出类似于“2天前”的字符串。
答案 0 :(得分：18)
这是我正在使用的助手类，扩展了Android的标准DateUtils。它具有高级逻辑，对于今天的时间戳，它将显示秒或分钟或小时，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，您将解析您在上面的代码中提取的Date date = formatter.parse(dateString);的时间戳。
代码逻辑符合您在Facebook或Twitter上所知的“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);
}
}
}
当strings.xml成立时：
<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>
答案 1 :(得分：4)
试试这个：
long currentTimeMillis = System.currentTimeMillis();
CharSequence string = DateUtils.getRelativeTimeSpanString(currentTimeMillis, currentTimeMillis + DateUtils.MINUTE_IN_MILLIS * 5, 0, DateUtils.FORMAT_ABBREV_ALL);
答案 2 :(得分：2)
可能有更好的方法可以做到这一点，但这很有效。
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());
}
答案 3 :(得分：1)
将其转换为日期。获取当前日期时间。计算差异。