より実用的なJavaの小さな道、いくつかの時間変換、

package cn.com.ultrapower.share;

import java.text.SimpleDateFormat;
import java.util.*;

public class FormatTime {

    private static Date time;

    private static SimpleDateFormat format;

    private static String strtime;

    /**
     * 将字符串类型转换为长整型(按格式)
     *
     * @param strDate
     * @param _format
     * @return
     */
    public static long formatToLongTime(String strDate, String _format) {
        format = new SimpleDateFormat(_format, Locale.getDefault());
        try {
            time = format.parse(strDate);
            return time.getTime() / 1000;
        } catch (Exception e) {
            e.printStackTrace();
            return -1;
        }
    }

    /**
     * 将长整型的日期转化为指定日期格式
     *
     * @param intDate
     * @return
     */
    public static String longToFormatTime(long intDate, String _format) {
        try {
            if (intDate > 0) {
                long c_unix_time2 = intDate;
                time = new Date();
                time.setTime(c_unix_time2 * 1000);
                format = new SimpleDateFormat(_format, Locale.getDefault());
                strtime = format.format(time);
            } else {
                strtime = "";
            }
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return strtime;
    }

    /**
     * 用于获得指定格式的当前日期
     *
     * @param _format
     *            日期格式
     */
    public static String getCurrentDate(String _format) {
        String currentDate = "";
        try {
            Calendar calendar = GregorianCalendar.getInstance();
            SimpleDateFormat simpleDateFormat;
            Date date = calendar.getTime();
            simpleDateFormat = new SimpleDateFormat(_format);
            currentDate = simpleDateFormat.format(date);
        } catch (Exception e) {
            e.printStackTrace();
            currentDate = "";
        }
        return currentDate;
    }

    /**
     * 获取时间差（可以通过此方法获取前N天的时间或前N个月的时间） 仔细摸索、其实这个方法挺实用的
     * @param strDate
     *            时间字符串
     * @param intDate
     *            时间差（秒）
     * @param _format
     *            时间格式（例：yyyy-MM-dd HH:mm:ss ，yyyyMMdd）
     * @return
     */
    public static String getCountTime(String strDate, long intDate,
            String _format) {
        try {
            long _intDate = FormatTime.formatToLongTime(strDate, _format);
            _intDate = intDate + _intDate;
            strDate = FormatTime.longToFormatTime(_intDate, _format);
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return strDate;
    }
    /**
     *
     * @param strTime 时间字符串
     * @param fmt1 旧时间格式
     * @param fmt2 新时间格式
     * ---yyyy-MM-dd HH:mm:ss
     * @return
     */
    public static String getTimeFMT_To_FMT(String strTime, String fmt1, String fmt2) {
        String strDate = "";
        try {
            long intDate = FormatTime.formatToLongTime(strTime, fmt1);
            strDate = FormatTime.longToFormatTime(intDate, fmt2);
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return strDate;
    }
     public static String formatIntToDateString01(long intDate,String fmt)
        {    
            if(intDate>0)
            {
                long c_unix_time2 = intDate;
                time = new Date();
                time.setTime(c_unix_time2*1000);
                format = new SimpleDateFormat(fmt, Locale.getDefault());
                strtime = format.format(time);
            }
            else
            {
                strtime="";
            }
            return strtime;
        }

    public static void main(String[] args) {
        String strTime = "2010-11-27 09:38:57";
        System.out.println(FormatTime.getTimeFMT_To_FMT(strTime,"yyyy-MM-dd HH:mm:ss", "yyyyMMddHHmmss"));
    }
}