java中如何获取时间戳的方法实例

public Long getToday(){
  DateTime now = new DateTime();
  return new DateTime(now.getYear(), now.getMonthOfYear(), now.getDayOfMonth(), 0, 0, 0, 0).getMillis();
 }
 
 public Long getTomorrow(){
  DateTime now = new DateTime();
  return new DateTime(now.getYear(), now.getMonthOfYear(), now.getDayOfMonth(), 0, 0, 0, 0).plusDays(1).getMillis();
 }

public Long getTime(){
  Long now = new Date().getTime();
  Calendar calendar = Calendar.getInstance();
  calendar.setTimeInMillis(now);
  calendar.set(Calendar.DAY_OF_MONTH, 5);
  calendar.set(Calendar.HOUR, 14);
  calendar.set(Calendar.MINUTE, 23);
  calendar.set(Calendar.SECOND, 6);
  calendar.set(Calendar.MILLISECOND, 138);
  return calendar.getTimeInMillis();
 }

public Long getTime(){
  Long now = new Date().getTime();
  Calendar calendar = Calendar.getInstance();
  calendar.setTimeInMillis(now);
  calendar.set(Calendar.DAY_OF_WEEK, 2);
  calendar.set(Calendar.HOUR, 10);
  calendar.set(Calendar.MINUTE, 10);
  calendar.set(Calendar.SECOND, 10);
  return calendar.getTimeInMillis();
 }

/** 
* 获取精确到秒的时间戳 
* @return 
*/ 
public static int getSecondTimestamp(Date date){ 
if (null == date) { 
return 0; 
} 
String timestamp = String.valueOf(date.getTime()); 
int length = timestamp.length(); 
if (length > 3) { 
return Integer.valueOf(timestamp.substring(0,length-3)); 
} else { 
return 0; 
} 
} 

/** 
* 获取精确到秒的时间戳 
* @param date 
* @return 
*/ 
public static int getSecondTimestampTwo(Date date){ 
if (null == date) { 
return 0; 
} 
String timestamp = String.valueOf(date.getTime()/1000); 
return Integer.valueOf(timestamp); 
}