比较时间大小

 

package com.weboa.util;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class DateTimeUtil {
	
	/**    
     * 得到几天前的时间    
      *     
      * @param d    
      * @param day    
      * @return    
      */     
     public static Date getDateBefore(Date d, int day) {      
         Calendar now = Calendar.getInstance();      
         now.setTime(d);      
         now.set(Calendar.DATE, now.get(Calendar.DATE) - day);      
         return now.getTime();      
     }     
  /**    
      * 得到几天后的时间    
      *     
      * @param d    
      * @param day    
      * @return    
      */     
     public static String getDateAfter(String startTime, int day) {
    	 String endTime="";
    	SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    	Date dateStart;
		try {
			dateStart = sdf.parse(startTime);
			Calendar now = Calendar.getInstance();      
	         now.setTime(dateStart);      
	        now.set(Calendar.DATE, now.get(Calendar.DATE) + day); 
	        endTime=sdf.format(now.getTime());
	               
		} catch (ParseException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return endTime;
        
     }  
     
     
     
     /*
      * java 比较时间大小
      */
      
     public static Integer getDateCompareTo(String startTime, String EndTime) {
    	 SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
         Calendar c1=Calendar.getInstance();
         Calendar c2=Calendar.getInstance();
         try
         {
         c1.setTime(sdf.parse(startTime));
         c2.setTime(sdf.parse(EndTime));
         }catch(java.text.ParseException e){
        	 System.err.println("格式不正确");
         }
         int result=c1.compareTo(c2);
         return result;
        
     } 
     
     /**    
      * 得到二个日期间的间隔天数    
      */     
  public static String getTwoDay(String sj1, String sj2) {      
      SimpleDateFormat myFormatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");      
      long day = 0;      
      try {      
       java.util.Date date = myFormatter.parse(sj1);      
       java.util.Date mydate = myFormatter.parse(sj2);      
       day = (date.getTime() - mydate.getTime()) / (24 * 60 * 60 * 1000);      
      } catch (Exception e) {      
       return "";      
      }      
      return day + "";      
  }   
    



}