Java獲取當前日期的前一個月，前一天的時間

Calendar calendar = Calendar.getInstance();   
calendar.add(Calendar.DATE, -1);    //得到前一天   
calendar.add(Calendar.MONTH, -1);    //得到前一個月   
int year = calendar.get(Calendar.YEAR);   
int month = calendar.get(Calendar.MONTH)+1;   
注意月份加一   
  
  
/**   
    * 判斷當前日期是星期幾<br>   
    * <br>   
    * @param pTime 修要判斷的時間<br>   
    * @return dayForWeek 判斷結果<br>   
    * @Exception 發生異常<br>   
    */    
public static int dayForWeek(String pTime) throws Exception {     
format = new SimpleDateFormat("yyyy-MM-dd");     
Calendar c = Calendar.getInstance();     
c.setTime(format.parse(pTime));     
int dayForWeek = 0;     
if(c.get(Calendar.DAY_OF_WEEK) == 1){     
  dayForWeek = 7;     
}else{     
  dayForWeek = c.get(Calendar.DAY_OF_WEEK) - 1;     
}     
return dayForWeek;     
}