在项目中,用到的关于时间操作的一些常用方法!!

package com.hoten.util;

import java.util.*;
import java.io.*;

/**
 * <p>Title: Time  </p>
 * <p>Description: </p>
 *      此类主要用来取得本地系统的系统时间并用下面5种格式显示
 *              1.　YYMMDDHH         8位
 *              2.　YYMMDDHHmm       10位
 *              3.　YYMMDDHHmmss     12位
 *              4.　YYYYMMDDHHmmss   14位
 *              5.　YYMMDDHHmmssxxx  15位 (最后的xxx 是毫秒)
 * <p>Copyright: Copyright (c) 2003</p>
 * <p>Company: c-platform</p>
 * @author WuJiaQian
 * @version 1.0
 */
public class CTime {
     public static final int YYMMDDhhmmssxxx = 15;
     public static final int YYYYMMDDhhmmss = 14;
     public static final int YYMMDDhhmmss = 12;
     public static final int YYMMDDhhmm = 10;
     public static final int YYMMDDhh = 8;

       /**
      * 取得本地系统的时间，时间格式由参数决定
      * @param format 时间格式由常量决定
      * @return　String 具有format格式的字符串
      */
     public static String getTime(int format) {
          StringBuffer cTime = new StringBuffer(15);
          Calendar time = Calendar.getInstance();
          int miltime = time.get(Calendar.MILLISECOND);
          int second = time.get(Calendar.SECOND);
          int minute = time.get(Calendar.MINUTE);
          int hour = time.get(Calendar.HOUR_OF_DAY);
          int day = time.get(Calendar.DAY_OF_MONTH);
          int month = time.get(Calendar.MONTH) + 1;
          int year = time.get(Calendar.YEAR);
          time = null;
          if (format != 14) {
               if (year >= 2000) year = year - 2000;
               else year = year - 1900;
          }
          if (format >= 2) {
               if (format == 14) cTime.append(year);
               else cTime.append(getFormatTime(year, 2));
          }
          if (format >= 4)
               cTime.append(getFormatTime(month, 2));
          if (format >= 6)
               cTime.append(getFormatTime(day, 2));
          if (format >= 8)
               cTime.append(getFormatTime(hour, 2));
          if (format >= 10)
               cTime.append(getFormatTime(minute, 2));
          if (format >= 12)
               cTime.append(getFormatTime(second, 2));
          if (format >= 15)
               cTime.append(getFormatTime(miltime, 3));
          return cTime.toString().trim();
     }

     /**
      *　产生任意位的字符串
      * @param time int 要转换格式的时间
      * @param format int　转换的格式
      * @return　String 转换的时间
      */

     public synchronized static String getYearAdd(int format, int iyear) {
          StringBuffer cTime = new StringBuffer(10);
          Calendar time = Calendar.getInstance();
          time.add(Calendar.YEAR, iyear);
          int miltime = time.get(Calendar.MILLISECOND);
          int second = time.get(Calendar.SECOND);
          int minute = time.get(Calendar.MINUTE);
          int hour = time.get(Calendar.HOUR_OF_DAY);
          int day = time.get(Calendar.DAY_OF_MONTH);
          int month = time.get(Calendar.MONTH) + 1;
          int year = time.get(Calendar.YEAR);
          if (format != 14) {
               if (year >= 2000) year = year - 2000;
               else year = year - 1900;
          }
          if (format >= 2) {
               if (format == 14) cTime.append(year);
               else cTime.append(getFormatTime(year, 2));
          }
          if (format >= 4)
               cTime.append(getFormatTime(month, 2));
          if (format >= 6)
               cTime.append(getFormatTime(day, 2));
          if (format >= 8)
               cTime.append(getFormatTime(hour, 2));
          if (format >= 10)
               cTime.append(getFormatTime(minute, 2));
          if (format >= 12)
               cTime.append(getFormatTime(second, 2));
          if (format >= 15)
               cTime.append(getFormatTime(miltime, 3));
          return cTime.toString();
     }

     /**
      *　产生任意位的字符串
      * @param time int 要转换格式的时间
      * @param format int　转换的格式
      * @return　String 转换的时间
      */
     private static String getFormatTime(int time, int format) {
          StringBuffer numm = new StringBuffer(format);
          int length = String.valueOf(time).length();

          if (format < length)return null;

          for (int i = 0; i < format - length; i++) {
               numm.append("0");
          }
          numm.append(time);
          return numm.toString().trim();
     }

     /**
      *　本函数主要作用是返回当前年份
      * @param len int 要转换年的位数
      * @return String 处理后的年 
      */

     public static String getYear(int len) {
          Calendar time = Calendar.getInstance();
          int year = time.get(Calendar.YEAR);
          String djyear = Integer.toString(year);
          if (len == 2) {
               djyear = djyear.substring(2);
          }
          return djyear;
     }

     /*
        #本函数作用是返回当前月份（2位）
      */
     public static String getMonth() {
          Calendar time = Calendar.getInstance();
          int month = time.get(Calendar.MONTH) + 1;
          String djmonth = "";
          if (month < 10) {
               djmonth = "0" + Integer.toString(month);
          }
          else {
               djmonth = Integer.toString(month);
          }
          return djmonth;
     }
     
      /*
        #本函数作用是返回上个月份（2位）
      */
     public static String getPreMonth() {
         Calendar time = Calendar.getInstance();
    int month = time.get(Calendar.MONTH);
    if (month == 0) month = 12;

    String djmonth = "";
         if (month < 10) {
             djmonth = "0" + Integer.toString(month);
         }
         else {
             djmonth = Integer.toString(month);
         }
         return djmonth;
     }

     /*
        #本函数主要作用是返回当前天数
      */
     public static String getDay() {
          Calendar time = Calendar.getInstance();
          int day = time.get(Calendar.DAY_OF_MONTH);
          String djday = "";
          if (day < 10) {
               djday = "0" + Integer.toString(day);
          }
          else {
               djday = Integer.toString(day);
          }
          return djday;
     }

     /*
        本函数作用是返回当前小时
      */
     public static String getHour() {
          Calendar time = Calendar.getInstance();
          int hour = time.get(Calendar.HOUR_OF_DAY);
          String djhour = "";
          if (hour < 10) {
               djhour = "0" + Integer.toString(hour);
          }
          else {
               djhour = Integer.toString(hour);
          }
          return djhour;
     }

     /*
        #本函数作用是返回当前分钟
      */
     public static String getMin() {
          Calendar time = Calendar.getInstance();
          int min = time.get(Calendar.MINUTE);
          String djmin = "";
          if (min < 10) {
               djmin = "0" + Integer.toString(min);
          }
          else {
               djmin = Integer.toString(min);
          }
          return djmin;
     }

     /*
        #本函数的主要功能是格式化时间，以便于页面显示
        #time 时间 可为6位、8位、12位、15位
        #return 返回格式化后的时间
        #6位 YY年MM月DD日
        #8位 YYYY年MM月DD日
        #12位 YY年MM月DD日 HH:II:SS
        #15位 YY年MM月DD日 HH:II:SS:CCC
      */
     public static String formattime(String time) {
          int length = 0;
          length = time.length();
          String renstr = "";
          switch (length) {
               case 6:
                    renstr = time.substring(0, 2) + "年" + time.substring(2, 4) +
                        "月" + time.substring(4) + "日";
                    break;
               case 8:
                    renstr = time.substring(0, 4) + "年" + time.substring(4, 6) +
                        "月" + time.substring(6, 8) + "日";
                    break;
               case 12:
                    renstr = time.substring(0, 2) + "年" + time.substring(2, 4) +
                        "月" + time.substring(4, 6) + "日 " + time.substring(6, 8) +
                        "时" + time.substring(8, 10) + "分" +
                        time.substring(10, 12) + "秒";
                    break;
               case 14:
                    renstr = time.substring(0, 4) + "-" + time.substring(4, 6) +
                        "-" + time.substring(6, 8) + " " + time.substring(8, 10) +
                        ":" + time.substring(10, 12) + ":" +
                        time.substring(12, 14) + "";
                    break;
               case 15:
                    renstr = time.substring(0, 2) + "年" + time.substring(2, 4) +
                        "月" + time.substring(4, 6) + "日 " + time.substring(6, 8) +
                        ":" + time.substring(8, 10) + ":" +
                        time.substring(10, 12) + ":" + time.substring(12);
                    break;
               default:
                    renstr = time.substring(0, 2) + "年" + time.substring(2, 4) +
                        "月" + time.substring(4) + "日";
                    break;
          }
          return renstr;
     }
}