时间函数

1、修改时间参数

            Calendar startTime =  Calendar.getInstance();
            startTime.set( Calendar.HOUR , 8 );
            startTime.set(Calendar.MINUTE, 00);  
            startTime.set(Calendar.SECOND, 00); 

2、Calendar 转化 String

         Calendar calendar = Calendar.getInstance();

       SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        String dateStr = sdf.format(calendar.getTime());

3、Date 转化Calendar

     Calendar calendar = Calendar.getInstance();
      calendar.setTime(new  Date() );

4、Calendar转化Date

     Calendar calendar = Calendar.getInstance();
      Date date =calendar.getTime();