日期处理工具类 -【一】

1、将一个字符串日期转换成日期格式

 1 /**
 2  * 将一个字符串日期转换成日期格式
 3  * @param date
 4  * @param pattern
 5  * @return
 6  */
 7 public static Date toDate(String date, String pattern) {
 8     if (("" + date).equals("")) {
 9         return null;
10     }
11     if (pattern == null) {
12         pattern = "yyyy-MM-dd";
13     }
14     SimpleDateFormat sdf = new SimpleDateFormat(pattern);
15     Date newDate = new Date();
16     try {
17         newDate = sdf.parse(date);
18     } catch (Exception ex) {
19         ex.printStackTrace();
20     }
21     return newDate;
22 }

2、把日期转换成字符串型

 1 /**
 2  * 把日期转换成字符串型
 3  * @param date
 4  * @param pattern
 5  * @return
 6  */
 7 public static String toString(Date date, String pattern) {
 8     if (date == null) {
 9         return "";
10     }
11     if (pattern == null) {
12         pattern = "yyyy-MM-dd";
13     }
14     String dateString = "";
15     SimpleDateFormat sdf = new SimpleDateFormat(pattern);
16     try {
17         dateString = sdf.format(date);
18     } catch (Exception ex) {
19         ex.printStackTrace();
20     }
21     return dateString;
22 }

3、计算两个日期之间相差的天数

 1 /**
 2  * 计算两个日期之间相差的天数
 3  * @param date1
 4  * @param date2
 5  * @return
 6  */
 7 public static int daysBetween(Date smdate,Date bdate)  {
 8     long between_days = 0;
 9     SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
10     try {
11         smdate = sdf.parse(sdf.format(smdate));
12         bdate = sdf.parse(sdf.format(bdate));
13         Calendar cal = Calendar.getInstance();
14         cal.setTime(smdate);
15         long time1 = cal.getTimeInMillis();
16         cal.setTime(bdate);
17         long time2 = cal.getTimeInMillis();
18         between_days=(time2-time1)/(1000*3600*24);
19     } catch (ParseException e) {
21         e.printStackTrace();
22     }
23     return Integer.parseInt(String.valueOf(between_days));
24 }