系統時間、星期、年月日

獲取系統的當前時間

long time = System.currentTimeMillis();

以不同的格式顯示
（1） 2015-11-11 11:08:34
（2） 2015/01/06 06-36-23
……

SimpleDateFormat sdff = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");  

Date date = new Date(System.currentTimeMillis());  

String str_date = sdf.format(date);  

通過Calendar類獲取年、月、日、星期（int類型1~7）

Calendar calendar = Calendar.getInstance();  

int year = calendar.get(Calendar.YEAR);  

//從0開始，一月得到的month=0 
int month = calendar.get(Calendar.MONTH);

int day = calendar.get(Calendar.DAY_OF_MONTH);  

int weekk = calendar.get(Calendar.DAY_OF_WEEK);  

獲取當前是星期幾

Date date = new Date(System.currentTimeMillis());  

Calendar calendar = Calendar.getInstance();  

calendar.setTime(date);  

String week = "周";  

if(calendar.get(Calendar.DAY_OF_WEEK) == 1)  
{  
    week +="日";  
}else if(calendar.get(Calendar.DAY_OF_WEEK) == 2)  
{  
    week +="一";  
}else if(calendar.get(Calendar.DAY_OF_WEEK) == 3)  
{  
    week +="二";  
}else if(calendar.get(Calendar.DAY_OF_WEEK) == 4)  
{  
    week +="三";  
}else if(calendar.get(Calendar.DAY_OF_WEEK) == 5)  
{  
    week +="四";  
}else if(calendar.get(Calendar.DAY_OF_WEEK) == 6)  
{  
    week +="五";  
}else if(calendar.get(Calendar.DAY_OF_WEEK) == 7)  
{  
    week +="六";  
}   

//最終獲取的格式是：週六