java计算两个任意日期间的相差的天数(自然天)

public int computeCoolingOffPeriod(String sBeginDate,String sEndDate)
{
Calendar calendar1=Calendar.getInstance();
Calendar calendar2=Calendar.getInstance();
try
{
SimpleDateFormat formatter1 = new SimpleDateFormat("yyyyMMdd");//格式很重要：是20051031，还是2005-10-31格式呢？

if (sBeginDate.equals("0"))
{
//System.out.println("sBirthDate.equals====0");
sBeginDate = "19000101";
}
calendar1.setTime(formatter1.parse(sBeginDate));
calendar2.setTime(formatter1.parse(sEndDate));

}
catch(Exception e)
{
e.printStackTrace();
}
return (int)( (calendar2.getTimeInMillis()-calendar1.getTimeInMillis())/1000/60/60/24 );//获取天数的差值。

}