Java 时间工具类

public class DateTimeUtil {
    public static String toString(Date date) {
        if (date == null || "".equals(date)) {
            return "";
        } else {
            DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm");
            return df.format(date);
        }
    }

    public static String dateToString(Date date) {
        if (date == null || "".equals(date)) {
            return "";
        } else {
            DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
            return df.format(date);
        }
    }

    public static String timeToString(Date date) {
        if (date == null || "".equals(date)) {
            return "";
        } else {
            DateFormat df = new SimpleDateFormat("HH:mm:ss");
            return df.format(date);
        }
    }

    public static Date parse(String str) throws ParseException {
        DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm");
//      System.out.println(str + "*****************");
        return df.parse(str);
    }

    public static Date toDate(String str) throws ParseException {
        DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        return df.parse(str);
    }

    public static Date getDate(Long num) {
        Date date = new Date();
        date.setTime(num * 1000);
        return date;
    }

    public static Date toDate(Long num) {
        Date date = new Date();
        date.setTime(num);
        return date;
    }

    public static Date toDate() {
        Date date = new Date();
        return date;
    }

    public static String toString(Timestamp stamp) {
        Date date = new Date();
        date.setTime(stamp.getTime());
        DateFormat df = new SimpleDateFormat("yyyy/MM/dd HH:mm" + "");
        return df.format(date);
    }

    public static Date toDate(Timestamp stamp) {
        Date date = new Date();
        date.setTime(stamp.getTime());
        return date;
    }

    public static Timestamp toTimestamp(Date date) {
        return new Timestamp(date.getTime());
    }

    public static String currentTimeKeyword() {

        return " sysdate ";
    }

    public static String getCurrentDate() {
        DateFormat df = new SimpleDateFormat("yyyyMMdd");
        return df.format(new Date());
    }

    public static String getCurrentTime() {
        DateFormat df = new SimpleDateFormat("HHmmss");
        return df.format(new Date());
    }

    /**
     * 格式化日期
     * 
     * @param date
     * @return yyyy-MM-dd
     */
    public static String formatDate(Integer date) {
        if (date == null || date == 0) {
            return "";
        }
        SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
        String string = "";
        try {
            Date date2 = sdf.parse(date + "");
            SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
            string = format.format(date2);
        } catch (ParseException e) {
        }
        return string;
    }

    /**
     * 格式化日期
     * 
     * @param date
     * @return yyyy-MM-dd
     */
    public static String formatDate(String date) {
        if (date == null || "".equals(date)) {
            return "";
        }
        SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
        String string = "";
        try {
            Date date2 = sdf.parse(date);
            SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
            string = format.format(date2);
        } catch (ParseException e) {
        }
        return string;
    }

    /**
     * 格式化日期
     * 
     * @param date
     * @return yyyy-MM-dd
     */
    public static String formatDate(Long date) {
        if (date == null || "".equals(date)) {
            return "";
        }
        SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMddHHmmss");
        String string = "";
        try {
            Date date2 = sdf.parse(date + "");
            SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
            string = format.format(date2);
        } catch (ParseException e) {
        }
        return string;
    }

    /**
     * 格式化时间
     * 
     * @param time
     * @return
     */
    public static String formatTime(String time) {
        if (time == null || "".equalsIgnoreCase(time)) {
            return time;
        }
        String timeString = "";
        SimpleDateFormat sdf = new SimpleDateFormat("HHmmss");
        try {
            Date date2 = sdf.parse(time);
            SimpleDateFormat format = new SimpleDateFormat("HH:mm:ss");
            timeString = format.format(date2);
        } catch (ParseException e) {
        }

        return timeString;
    }

    /**
     * 验证日期的合法性
     * 
     * @param date
     * @return
     */
    public static boolean volidateDate(String date) {

        boolean flg = true;
        SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
        sdf.setLenient(false);
        try {
            if (date.length() == 8) {
                sdf.parse(date);
                flg = true;
            } else {
                flg = false;
            }

        } catch (ParseException e) {
            flg = false;
        }
        return flg;

    }

    /**
     * 当月第一天
     * 
     * @return
     */
    public static String getFirstDay() {
        SimpleDateFormat df = new SimpleDateFormat("yyyyMMdd");
        Calendar gcLast = Calendar.getInstance();
        gcLast.set(Calendar.DAY_OF_MONTH, 1);
        String day_first = df.format(gcLast.getTime());
        StringBuffer str = new StringBuffer().append(day_first);
        return str.toString();

    }

    /**
     * 当月最后一天
     * 
     * @return
     */
    public static String getLastDay() {
        SimpleDateFormat df = new SimpleDateFormat("yyyyMMdd");
        Calendar calendar = Calendar.getInstance();
        int maxDay = calendar.getActualMaximum(calendar.DAY_OF_MONTH);
        calendar.set(Calendar.DAY_OF_MONTH, maxDay);
        Date theDate = calendar.getTime();
        String s = df.format(theDate);
        StringBuffer str = new StringBuffer().append(s);
        return str.toString();

    }

    /**
     * 得到某年某月的第一天
     * 
     * @param year
     * @param month
     * @return
     */
    public static String getFirstDayOfMonth(int year, int month) {

        Calendar cal = Calendar.getInstance();

        cal.set(Calendar.YEAR, year);

        cal.set(Calendar.MONTH, month - 1);

        cal.set(Calendar.DAY_OF_MONTH, cal.getMinimum(Calendar.DATE));

        return new SimpleDateFormat("yyyyMMdd").format(cal.getTime());
    }

    /**
     * 得到某年某月的最后一天
     * 
     * @param year
     * @param month
     * @return
     */
    public static String getLastDayOfMonth(int year, int month) {

        Calendar cal = Calendar.getInstance();

        cal.set(Calendar.YEAR, year);

        cal.set(Calendar.MONTH, month - 1);

        cal.set(Calendar.DAY_OF_MONTH, 1);
        int value = cal.getActualMaximum(Calendar.DAY_OF_MONTH);
        cal.set(Calendar.DAY_OF_MONTH, value);

        return new SimpleDateFormat("yyyyMMdd").format(cal.getTime());

    }