public class Test1 {
    public static void main(String[]args){
        System.out.println("時間為：\n"+getDate1()+"\n"+getDate2()+"\n"+getDate3()+"\n"+getDate4()+"\n"+getDate5());
    }
	
/*	Calendar.HOUR_OF_DAY 	24小時制
	Calendar.HOUR 	12小時制*/
	
	//獲取當天0點時間
	public static String getDate1(){
		 Calendar cal = Calendar.getInstance();
		 cal.set(Calendar.HOUR_OF_DAY, 0);//控制時
		 cal.set(Calendar.MINUTE, 0);//控制分
		 cal.set(Calendar.SECOND, 0);//控制秒
		 SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		 return sdf.format(cal.getTime());
	}
	
	//獲取當天12點時間
	public static String getDate2(){
		 Calendar cal = Calendar.getInstance();
		 cal.set(Calendar.HOUR_OF_DAY, 12);
		 cal.set(Calendar.MINUTE, 0);
		 cal.set(Calendar.SECOND, 0);
		 SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		 return sdf.format(cal.getTime());
	}	
	
	//獲取本週一0點時間
	public static String getDate3(){
		 Calendar cal = Calendar.getInstance();
		 cal.set(cal.get(Calendar.YEAR),cal.get(Calendar.MONDAY), cal.get(Calendar.DAY_OF_MONTH), 0, 0,0);
		 cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
		 SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		 return sdf.format(cal.getTime());
	}	
	
	//獲取本月第一天0點時間
	public static String getDate4(){
		 Calendar cal = Calendar.getInstance();
		 cal.set(cal.get(Calendar.YEAR),cal.get(Calendar.MONDAY), cal.get(Calendar.DAY_OF_MONTH), 0, 0,0);
		 cal.set(Calendar.DAY_OF_MONTH,cal.getActualMinimum(Calendar.DAY_OF_MONTH));
		 SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		 return sdf.format(cal.getTime());
	}
	
         //獲得本月最後一天24點時間
	public static String getDate5(){
		 Calendar cal = Calendar.getInstance();
		 cal.set(cal.get(Calendar.YEAR),cal.get(Calendar.MONDAY), cal.get(Calendar.DAY_OF_MONTH), 0, 0,0);
		 cal.set(Calendar.DAY_OF_MONTH,cal.getActualMaximum(Calendar.DAY_OF_MONTH));
		 cal.set(Calendar.HOUR_OF_DAY, 24);
		 SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		 return sdf.format(cal.getTime());
	}		

}