获得当前日期前几天的日期(不包含当天)

//获得当前日期前几天的日期(不包含当天),dataStr为给定日期,count为前几天
	public String getBeforeDate(String dateStr,int count){
        SimpleDateFormat sdf  = new SimpleDateFormat("yyyy-MM-dd");  
        String maxDateStr = dateStr;  
        String minDateStr = "";  
        Calendar calc =Calendar.getInstance();  
        try {  
            calc.setTime(sdf.parse(maxDateStr));  
            calc.add(calc.DATE, count);  
            Date minDate = calc.getTime();  
            minDateStr = sdf.format(minDate);  
            return minDateStr;
        } catch (ParseException e1) {  
            e1.printStackTrace();  
        }
        return null;
	}
//获取当前日期前一天的日期:
        public String lastDate() {
		Calendar calendar = new GregorianCalendar();
		 Date date=new Date();
		   calendar.setTime(date);
		   calendar.add(calendar.DATE,-1);//把日期往后增加一天.整数往后推,负数往前移动
		   date=calendar.getTime();
		   SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");
		   return formatter.format(date);
        }
//获得给定时间前30天的所有日期(包含给定时间)

public void getLastDays(String maxDateStr,int count){

     SimpleDateFormat sdf  = new SimpleDateFormat("yyyy-MM-dd");    
     String minDateStr = "";    
     Calendar calc =Calendar.getInstance();    
     try {    
         for(int i=0;i<count;i++){  
           calc.setTime(sdf.parse(maxDateStr));    
          calc.add(calc.DATE, -i);    
          Date minDate = calc.getTime();    
          minDateStr = sdf.format(minDate);    
          System.out.println(i+":minDateStr:"+minDateStr);//minDateStr:2017-01-09   正确！！！！    
         }  
     } catch (ParseException e1) {      
         e1.printStackTrace();    
     } 

}