日期时间格式转换方法

1、Calendar转换成Date

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

2、Date 转换成 Calendar

Date date = new Date();
Calendar cal = Calendar.getInstance();
Cal.setTime(date );

3、SimpleDateFormat 方法

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); 
String date = sdf.format(new Date());