Java:String和Date、Timestamp之间的转换
一、String与Date(java.util.Date)互转
1.1 String -> Date
- String dateStr = "2010/05/04 12:34:23";
- Date date = new Date();
- //注意format的格式要与日期String的格式相匹配
- DateFormat sdf = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
- try {
- date = sdf.parse(dateStr);
- System.out.println(date.toString());
- } catch (Exception e) {
- e.printStackTrace();
- }
String dateStr = "2010/05/04 12:34:23"; Date date = new Date(); //注意format的格式要与日期String的格式相匹配 DateFormat sdf = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss"); try { date = sdf.parse(dateStr); System.out.println(date.toString()); } catch (Exception e) { e.printStackTrace(); }
1.2 Date -> String
日期向字符串转换,可以设置任意的转换格式format
- String dateStr = "";
- Date date = new Date();
- //format的格式可以任意
- DateFormat sdf = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
- DateFormat sdf2 = new SimpleDateFormat("yyyy-MM-dd HH/mm/ss");
- try {
- dateStr = sdf.format(date);
- System.out.println(dateStr);
- dateStr = sdf2.format(date);
- System.out.println(dateStr);
- } catch (Exception e) {
- e.printStackTrace();
- }
String dateStr = ""; Date date = new Date(); //format的格式可以任意 DateFormat sdf = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss"); DateFormat sdf2 = new SimpleDateFormat("yyyy-MM-dd HH/mm/ss"); try { dateStr = sdf.format(date); System.out.println(dateStr); dateStr = sdf2.format(date); System.out.println(dateStr); } catch (Exception e) { e.printStackTrace(); }
二、String与Timestamp互转
2.1 String ->Timestamp
使用Timestamp的valueOf()方法
- Timestamp ts = new Timestamp(System.currentTimeMillis());
- String tsStr = "2011-05-09 11:49:45";
- try {
- ts = Timestamp.valueOf(tsStr);
- System.out.println(ts);
- } catch (Exception e) {
- e.printStackTrace();
- }
Timestamp ts = new Timestamp(System.currentTimeMillis()); String tsStr = "2011-05-09 11:49:45"; try { ts = Timestamp.valueOf(tsStr); System.out.println(ts); } catch (Exception e) { e.printStackTrace(); }
注:String的类型必须形如: yyyy-mm-dd hh:mm:ss[.f...] 这样的格式,中括号表示可选,否则报错!!!
如果String为其他格式,可考虑重新解析下字符串,再重组~~
2.2 Timestamp -> String
使用Timestamp的toString()方法或者借用DateFormat
- Timestamp ts = new Timestamp(System.currentTimeMillis());
- String tsStr = "";
- DateFormat sdf = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
- try {
- //方法一
- tsStr = sdf.format(ts);
- System.out.println(tsStr);
- //方法二
- tsStr = ts.toString();
- System.out.println(tsStr);
- } catch (Exception e) {
- e.printStackTrace();
- }
Timestamp ts = new Timestamp(System.currentTimeMillis()); String tsStr = ""; DateFormat sdf = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss"); try { //方法一 tsStr = sdf.format(ts); System.out.println(tsStr); //方法二 tsStr = ts.toString(); System.out.println(tsStr); } catch (Exception e) { e.printStackTrace(); }
很容易能够看出来,方法一的优势在于可以灵活的设置字符串的形式。
三、Date( java.util.Date )和Timestamp互转
声明:查API可知,Date和Timesta是父子类关系
3.1 Timestamp -> Date
- Timestamp ts = new Timestamp(System.currentTimeMillis());
- Date date = new Date();
- try {
- date = ts;
- System.out.println(date);
- } catch (Exception e) {
- e.printStackTrace();
- }
Timestamp ts = new Timestamp(System.currentTimeMillis()); Date date = new Date(); try { date = ts; System.out.println(date); } catch (Exception e) { e.printStackTrace(); }
很简单,但是此刻date对象指向的实体却是一个Timestamp,即date拥有Date类的方法,但被覆盖的方法的执行实体在Timestamp中。
3.2 Date -> Timestamp
父类不能直接向子类转化,可借助中间的String~~~~
注:使用以下方式更简洁
Timestamp ts = new Timestamp(date.getTime());