[Java] 如何将String转成Data对象

下面的代码说明如何将String类型的日期转换成java.util.Date类型的对象。为了实现转换，我们使用java.text.SimpleTextFormat类，它继承自java.txt.TextFormat抽象类。

 

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.text.ParseException;
import java.util.Date;

public class StringToDate
{
    public static void main(String[] args)
    {
        DateFormat df = new SimpleDateFormat("dd/MM/yyyy");

        try
        {
            Date today = df.parse("20/12/2005");
            System.out.println("Today = " + df.format(today));
        } catch (ParseException e)
        {
            e.printStackTrace();
        }
    }
}

下面是代码的结果：

 

 

Today = 20/12/2005

例子的开始部分创建了一个“dd/MM/yyyy”格式的SimpleDateFormat对象，它意味着要转换的日期字符串的格式是日期、月、年。

 

最后，通过使用parse(String srouce)函数得到一个Date类的实例。由于当给定的字符串不符合给定格式时，parse对象跑出ParseException异常，我们需要捕获它。

下面的列表是从javadoc文档中摘取的用来格式化Date对象的一些预定义的模式。

Letter	Date / Time Component	Examples
G	Era designator	AD
y	Year	1996; 96
M	Month in year	July; Jul; 07
w	Week in year	27
W	Week in month	2
D	Day in year	189
d	Day in month	10
F	Day of week in month	2
E	Day in week	Tuesday; Tue
a	Am/pm marker	PM
H	Hour in day (0-23)	0
k	Hour in day (1-24)	24
K	Hour in am/pm (0-11)	0
h	Hour in am/pm (1-12)	12
m	Minute in hour	30
s	Second in minute	55
S	Millisecond	978
z	Time zone	Pacific Standard Time; PST; GMT-08:00
Z	Time zone	-0800

 

该例子来自：http://www.kodejava.org/examples/19.html

table cellpadding="3" cellspacing="0" border="1" width="100%">
<tr>
    <td align="left">Letter</td>
    <td align="left">Date / Time Component</td>
    <td align="left">Examples</td>
</tr>
<tr>

    <td>G</td>
    <td>Era designator</td>
    <td>AD</td>
</tr>
<tr>
    <td>y</td>
    <td>Year</td>

    <td>1996; 96</td>
</tr>
<tr>
    <td>M</td>
    <td>Month in year</td>
    <td>July; Jul; 07</td>
</tr>
<tr>
    <td>w</td>

    <td>Week in year</td>
    <td>27</td>
</tr>
<tr>
    <td>W</td>
    <td>Week in month</td>
    <td>2</td>

</tr>
<tr>
    <td>D</td>
    <td>Day in year</td>
    <td>189</td>
</tr>
<tr>
    <td>d</td>
    <td>Day in month</td>

    <td>10</td>
</tr>
<tr>
    <td>F</td>
    <td>Day of week in month</td>
    <td>2</td>
</tr>
<tr>
    <td>E</td>

    <td>Day in week</td>
    <td>Tuesday; Tue</td>
</tr>
<tr>
    <td>a</td>
    <td>Am/pm marker</td>
    <td>PM</td>

</tr>
<tr>
    <td>H</td>
    <td>Hour in day (0-23)</td>
    <td>0</td>
</tr>
<tr>
    <td>k</td>
    <td>Hour in day (1-24)</td>

    <td>24</td>
</tr>
<tr>
    <td>K</td>
    <td>Hour in am/pm (0-11)</td>
    <td>0</td>
</tr>
<tr>
    <td>h</td>

    <td>Hour in am/pm (1-12)</td>
    <td>12</td>
</tr>
<tr>
    <td>m</td>
    <td>Minute in hour</td>
    <td>30</td>

</tr>
<tr>
    <td>s</td>
    <td>Second in minute</td>
    <td>55</td>
</tr>
<tr>
    <td>S</td>
    <td>Millisecond</td>

    <td>978</td>
</tr>
<tr>
    <td>z</td>
    <td>Time zone</td>
    <td>Pacific Standard Time; PST; GMT-08:00</td>
</tr>
<tr>
    <td>Z</td>

    <td>Time zone</td>
    <td>-0800</td>
</tr>
</table>