日期类

package org.ilog.jsp;

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

public class formatDate {

  public formatDate() {
  }

  // 格式化日期为字符串 "yyyy-MM-dd hh:mm"
  public String formatDateTime(Date basicDate,String strFormat) {
    SimpleDateFormat df = new SimpleDateFormat(strFormat);
    return df.format(basicDate);
  }

  // 格式化日期为字符串 "yyyy-MM-dd hh:mm"
  public String formatDateTime(String basicDate,String strFormat) {
    SimpleDateFormat df = new SimpleDateFormat(strFormat);
    Date tmpDate=null;
    try {
      tmpDate=df.parse(basicDate);
    }
    catch(Exception e) {
      // 日期型字符串格式错误
    }
    return df.format(tmpDate);
  }

  // 当前日期加减n天后的日期，返回String (yyyy-mm-dd)
  public String nDaysAftertoday(int n) {
    SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
    Calendar rightNow = Calendar.getInstance();
    //rightNow.add(Calendar.DAY_OF_MONTH,-1);
    rightNow.add(Calendar.DAY_OF_MONTH,+n);
    return df.format(rightNow.getTime());
  }

  // 当前日期加减n天后的日期，返回String (yyyy-mm-dd)
  public Date nDaysAfterNowDate(int n) {
    Calendar rightNow = Calendar.getInstance();
    //rightNow.add(Calendar.DAY_OF_MONTH,-1);
    rightNow.add(Calendar.DAY_OF_MONTH,+n);
    return rightNow.getTime();
  }

  // 给定一个日期型字符串，返回加减n天后的日期型字符串
  public String nDaysAfterOneDateString(String basicDate,int n) {
    SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
    Date tmpDate = null;
    try {
      tmpDate = df.parse(basicDate);
    }
    catch(Exception e){
      // 日期型字符串格式错误
    }
    long nDay=(tmpDate.getTime()/(24*60*60*1000)+1+n)*(24*60*60*1000);
    tmpDate.setTime(nDay);

    return df.format(tmpDate);
  }

  // 给定一个日期，返回加减n天后的日期
  public Date nDaysAfterOneDate(Date basicDate,int n) {
    long nDay=(basicDate.getTime()/(24*60*60*1000)+1+n)*(24*60*60*1000);
    basicDate.setTime(nDay);

    return basicDate;
  }

  // 计算两个日期相隔的天数
  public int nDaysBetweenTwoDate(Date firstDate,Date secondDate) {
    int nDay=(int)((secondDate.getTime()-firstDate.getTime())/(24*60*60*1000));
    return nDay;
  }

  // 计算两个日期相隔的天数
  public int nDaysBetweenTwoDate(String firstString,String secondString) {
    SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
    Date firstDate=null;
    Date secondDate=null;
    try {
      firstDate = df.parse(firstString);
      secondDate=df.parse(secondString);
    }
    catch(Exception e) {
      // 日期型字符串格式错误
    }

    int nDay=(int)((secondDate.getTime()-firstDate.getTime())/(24*60*60*1000));
    return nDay;
  }

}