关于日期计算的小代码

if ("02".equals(freq)){ //处理周的情况

     DateFormat   df=new   SimpleDateFormat("yyyyMMdd");   

     Calendar   c=Calendar.getInstance();   

     try {

c.setTime(df.parse(date));

c.setFirstDayOfWeek(Calendar.MONDAY);   

int   day=c.get(Calendar.DAY_OF_WEEK); 

if ((day-2) == 0) {//等于2，说明是周一

return date;

} else if((day-2) > 0) {

c.add(Calendar.DATE,-(day-2));

String sDateString = df.format(c.getTime()); 

return sDateString;

}else if((day-2) == -1){

c.add(Calendar.DATE,(day-7));

String sDateString = df.format(c.getTime()); 

return sDateString;

}

} catch (ParseException e) {

// TODO Auto-generated catch block

e.printStackTrace();

} 

上面是开发时，遇到日期计算时，写的代码，留作备用吧