21.Android 时间工具DateUtil

String 转换 Date

    /**
     * String 转换 Date
     *
     * @param str
     * @param format
     * @return
     */
    public static Date string2Date(String str, String format) {
        try {
            return new SimpleDateFormat(format).parse(str);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return new Date();
    }

long 转换 String

    /**
     * Date（long） 转换 String
     *
     * @param time
     * @param format
     * @return
     */
    public static String date2String(long time, String format) {
        SimpleDateFormat sdf = new SimpleDateFormat(format);
        String s = sdf.format(time);
        return s;
    }

long 去除 时分秒

    /**
     * long 去除 时分秒
     * 时分秒全部为0
     *
     * @param date
     * @return
     */
    public static long getYearMonthDay(long date) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTimeInMillis(date);
        calendar.set(Calendar.HOUR_OF_DAY, 0);
        calendar.set(Calendar.SECOND, 0);
        calendar.set(Calendar.MINUTE, 0);
        calendar.set(Calendar.MILLISECOND, 0);
        return calendar.getTimeInMillis();
    }

计算时间差

    /**
     * 获取目标时间和当前时间之间的差距
     *
     * @param date
     * @return
     */
    public static String getTimestampString(Date date) {
        Date curDate = new Date();
        long splitTime = curDate.getTime() - date.getTime();
        if (splitTime < (30 * ONE_DAY)) {
            if (splitTime < ONE_MINUTE) {
                return "刚刚";
            }
            if (splitTime < ONE_HOUR) {
                return String.format("%d分钟前", splitTime / ONE_MINUTE);
            }

            if (splitTime < ONE_DAY) {
                return String.format("%d小时前", splitTime / ONE_HOUR);
            }

            return String.format("%d天前", splitTime / ONE_DAY);
        }
        String result;
        result = "M月d日 HH:mm";
        return (new SimpleDateFormat(result, Locale.CHINA)).format(date);
    }

24小时制转12小时制

    /**
     * 24小时制 转换 12小时制
     *
     * @param time
     * @return
     */
    public static String time24To12(String time) {
        String str[] = time.split(":");
        int h = Integer.valueOf(str[0]);
        int m = Integer.valueOf(str[1]);
        String sx;
        if (h < 1) {
            h = 12;
            sx = "上午";
        } else if (h < 12) {
            sx = "上午";
        } else if (h < 13) {
            sx = "下午";
        } else {
            sx = "下午";
            h -= 12;
        }
        return String.format("%d:%02d%s", h, m, sx);
    }

Date 转换 String

    public static String[] WEEK = new String[]{"天", "一", "二", "三", "四", "五", "六"};

    private static final long ONE_SECOND = 1000;
    private static final long ONE_MINUTE = ONE_SECOND * 60;
    private static final long ONE_HOUR = ONE_MINUTE * 60;
    private static final long ONE_DAY = ONE_HOUR * 24;

    /**
     * Date 转换 HH
     * 
     * @param date
     * @return
     */
    public static String date2HH(Date date) {
        return new SimpleDateFormat("HH").format(date);
    }

    /**
     * Date 转换 HH:mm:ss
     *
     * @param date
     * @return
     */
    public static String date2HHmm(Date date) {
        return new SimpleDateFormat("HH:mm").format(date);
    }

    /**
     * Date 转换 HH:mm:ss
     *
     * @param date
     * @return
     */
    public static String date2HHmmss(Date date) {
        return new SimpleDateFormat("HH:mm:ss").format(date);
    }

    /**
     * Date 转换 MM.dd
     *
     * @param date
     * @return
     */
    public static String date2MMdd(Date date) {
        return new SimpleDateFormat("MM.dd").format(date);
    }

    /**
     * Date 转换 yyyy.MM.dd
     *
     * @param date
     * @return
     */
    public static String date2yyyyMMdd(Date date) {
        return new SimpleDateFormat("yyyy.MM.dd").format(date);
    }

    /**
     * Date 转换 MM月dd日 星期
     *
     * @param date
     * @return
     */
    public static String date2MMddWeek(Date date) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        int dayOfWeek = calendar.get(Calendar.DAY_OF_WEEK);
        return new SimpleDateFormat("MM月dd日 星期").format(date) + week[dayOfWeek - 1];
    }

    /**
     * Date 转换 yyyy年MM月dd日 星期
     *
     * @param date
     * @return
     */
    public static String date2yyyyMMddWeek(Date date) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        int dayOfWeek = calendar.get(Calendar.DAY_OF_WEEK);
        return new SimpleDateFormat("yyyy年MM月dd日 星期").format(date) + week[dayOfWeek - 1];
    }

DateUtil全部源码

public class DateUtil {

    public static String[] WEEK = new String[]{"天", "一", "二", "三", "四", "五", "六"};

    private static final long ONE_SECOND = 1000;
    private static final long ONE_MINUTE = ONE_SECOND * 60;
    private static final long ONE_HOUR = ONE_MINUTE * 60;
    private static final long ONE_DAY = ONE_HOUR * 24;

    /**
     * String 转换 Date
     *
     * @param str
     * @param format
     * @return
     */
    public static Date string2Date(String str, String format) {
        try {
            return new SimpleDateFormat(format).parse(str);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return new Date();
    }

    /**
     * Date（long） 转换 String
     *
     * @param time
     * @param format
     * @return
     */
    public static String date2String(long time, String format) {
        SimpleDateFormat sdf = new SimpleDateFormat(format);
        String s = sdf.format(time);
        return s;
    }

    /**
     * long 去除 时分秒
     * 时分秒全部为0
     *
     * @param date
     * @return
     */
    public static long getYearMonthDay(long date) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTimeInMillis(date);
        calendar.set(Calendar.HOUR_OF_DAY, 0);
        calendar.set(Calendar.SECOND, 0);
        calendar.set(Calendar.MINUTE, 0);
        calendar.set(Calendar.MILLISECOND, 0);
        return calendar.getTimeInMillis();
    }

    /**
     * 获取目标时间和当前时间之间的差距
     *
     * @param date
     * @return
     */
    public static String getTimestampString(Date date) {
        Date curDate = new Date();
        long splitTime = curDate.getTime() - date.getTime();
        if (splitTime < (30 * ONE_DAY)) {
            if (splitTime < ONE_MINUTE) {
                return "刚刚";
            }
            if (splitTime < ONE_HOUR) {
                return String.format("%d分钟前", splitTime / ONE_MINUTE);
            }

            if (splitTime < ONE_DAY) {
                return String.format("%d小时前", splitTime / ONE_HOUR);
            }

            return String.format("%d天前", splitTime / ONE_DAY);
        }
        String result;
        result = "M月d日 HH:mm";
        return (new SimpleDateFormat(result, Locale.CHINA)).format(date);
    }

    /**
     * 24小时制 转换 12小时制
     *
     * @param time
     * @return
     */
    public static String time24To12(String time) {
        String str[] = time.split(":");
        int h = Integer.valueOf(str[0]);
        int m = Integer.valueOf(str[1]);
        String sx;
        if (h < 1) {
            h = 12;
            sx = "上午";
        } else if (h < 12) {
            sx = "上午";
        } else if (h < 13) {
            sx = "下午";
        } else {
            sx = "下午";
            h -= 12;
        }
        return String.format("%d:%02d%s", h, m, sx);
    }

    /**
     * Date 转换 HH
     *
     * @param date
     * @return
     */
    public static String date2HH(Date date) {
        return new SimpleDateFormat("HH").format(date);
    }

    /**
     * Date 转换 HH:mm:ss
     *
     * @param date
     * @return
     */
    public static String date2HHmm(Date date) {
        return new SimpleDateFormat("HH:mm").format(date);
    }

    /**
     * Date 转换 HH:mm:ss
     *
     * @param date
     * @return
     */
    public static String date2HHmmss(Date date) {
        return new SimpleDateFormat("HH:mm:ss").format(date);
    }

    /**
     * Date 转换 MM.dd
     *
     * @param date
     * @return
     */
    public static String date2MMdd(Date date) {
        return new SimpleDateFormat("MM.dd").format(date);
    }

    /**
     * Date 转换 yyyy.MM.dd
     *
     * @param date
     * @return
     */
    public static String date2yyyyMMdd(Date date) {
        return new SimpleDateFormat("yyyy.MM.dd").format(date);
    }

    /**
     * Date 转换 MM月dd日 星期
     *
     * @param date
     * @return
     */
    public static String date2MMddWeek(Date date) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        int dayOfWeek = calendar.get(Calendar.DAY_OF_WEEK);
        return new SimpleDateFormat("MM月dd日 星期").format(date) + WEEK[dayOfWeek - 1];
    }

    /**
     * Date 转换 yyyy年MM月dd日 星期
     *
     * @param date
     * @return
     */
    public static String date2yyyyMMddWeek(Date date) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        int dayOfWeek = calendar.get(Calendar.DAY_OF_WEEK);
        return new SimpleDateFormat("yyyy年MM月dd日 星期").format(date) + WEEK[dayOfWeek - 1];
    }

}