Java日期格式化及其运用例子收集

Java日期格式化及其使用例子收集

1 SimpleDateFormat担当重任,怎样格式化都行

<span style="font-size:12px;">import java.util.Date;
import java.text.SimpleDateFormat;
<span class="kwrd">public </span><span class="kwrd">class</span> Demo
{
 <span class="kwrd">public </span><span class="kwrd">static </span><span class="kwrd">void</span> main(String[] args)
 {
  <u>Date now=<span class="kwrd">new</span> Date();</u>
  SimpleDateFormat f=<span class="kwrd">new</span><strong><u>SimpleDateFormat</u></strong>(<span class="str">"今天是"</span>+<span class="str">"yyyy年MM月dd日 E kk点mm分"</span>);
  System.<span class="kwrd">out</span>.println(f.format(now));
  
  f=<span class="kwrd">new</span> SimpleDateFormat(<span class="str">"a hh点mm分ss秒"</span>);
  System.<span class="kwrd">out</span>.println(f.format(now));
  }
 }
		</span>

2 从字符串到日期类型的转换：

<span style="font-size:12px;">import java.util.Date;
import java.text.SimpleDateFormat;
import java.util.GregorianCalendar;
import java.text.*;
<span class="kwrd">public</span><span class="kwrd">class</span> Demo
{
 <span class="kwrd">public </span><span class="kwrd">static </span><span class="kwrd">void</span> main(String[] args)
 {
  String strDate=<span class="str">"2005年04月22日"</span>;
<span class="rem">  //注意：SimpleDateFormat构造函数的样式与strDate的样式必须相符</span>
  SimpleDateFormat simpleDateFormat=<span class="kwrd">new</span> SimpleDateFormat(<span class="str">"yyyy年MM月dd日"</span>);
<span class="rem">  //必须捕获异常</span></span>

<span style="font-size:12px;"><span class="rem">  </span><span class="kwrd">try</span>
  { 
   Date date=simpleDateFormat.parse(strDate);
   System.<span class="kwrd">out</span>.println(date);
  }
  <span class="kwrd">catch</span>(ParseException px)
  {
   px.printStackTrace();
  }
 }
}
		</span>

3 将毫秒数换转成日期类型

<span style="font-size:12px;">import java.util.Date;
import java.text.SimpleDateFormat;
import java.util.GregorianCalendar;
import java.text.*;
<span class="kwrd">public </span><span class="kwrd">class</span> Demo
{
 <span class="kwrd">public </span><span class="kwrd">static </span><span class="kwrd">void</span> main(String[] args)
 {
  <span class="kwrd">long</span> now=System.currentTimeMillis();
  System.<span class="kwrd">out</span>.println(<span class="str">"毫秒数："</span>+now);
  Date dNow=<span class="kwrd">new</span> Date(now);
  System.<span class="kwrd">out</span>.println(<span class="str">"日期类型："</span>+dNow);
 }
}</span>

<span style="font-size:12px;">
这3例源自</span><span style="font-size:12px;">http://blog.csdn.net/zhoujian2003/archive/2005/04/22/358363.aspx</span>

4 获取系统时期和时间，转换成SQL格式后更新到数据库

(http://blog.csdn.net/netrope/archive/2005/11/19/532729.aspx)

<span style="font-size:12px;">java.util.Date d=<span class="kwrd">new</span> java.util.Date();    <span class="rem">//获取当前系统的时间</span></span>

<span style="FONT-SIZE: 12px"><span class="rem"><span style="color:#000000;"> <span class="rem">//格式化日期</span></span></span></span>

<span style="font-size:12px;"><span class="rem"></span><span class="kwrd">new</span> java.text.SimpleDateFormat s= <span class="kwrd">new</span> java.text.SimpleDateFormat(<span class="str">"yyyy-MM-dd HH:mm:ss"</span>);</span>

<span style="font-size:12px;">String dateStr = s.format(d); <span class="rem">//转为字符串</span>	</span>

使用RS更新数据库，仍然要用rs.updateString，而不是rs.updateDade。

rs.updateString("regtime",dateStr); //regtime字段为datetime类型的

下面两例源自 http://blog.csdn.net/kingter520/archive/2004/10/27/155435.aspx

5 按本地时区输出当前日期

<span style="font-size:12px;">Date myDate = <span class="kwrd">new</span> Date();
System.<span class="kwrd">out</span>.println(myDate.toLocaleString());
输出结果为：
2003-5-30
		</span>

6 如何格式化小数

<span style="font-size:12px;">DecimalFormat df = <span class="kwrd">new</span> DecimalFormat(<span class="str">",###.00"</span>);   
<span class="kwrd">double</span> aNumber = 33665448856.6568975; 
String result = df.format(aNumber);   
Sytem. <span class="kwrd">out</span>.println(result);
	</span>

<span style="font-size:12px;">输出结果为：
33,665,448,856.66 </span>

其他：获取毫秒时间 System.currentTimeMillis();

7 在数据库里的日期只以年-月-日的方式输出

(http://blog.csdn.net/zzsxvzzsxv/archive/2007/08/27/1761004.aspx)

定义日期格式：SimpleDateFormat sdf = new SimpleDateFormat(yy-MM-dd);

sql语句为：String sqlStr = "select bookDate from roomBook where bookDate between '2007-4-10' and '2007-4-25'";

输出：

System.out.println(df.format(rs.getDate("bookDate")));

8 经典例子(http://blog.csdn.net/donkeyzheng/archive/2005/12/30/566470.aspx)

<span style="font-size:12px;">Date date = from.getAfmdate();
<span class="kwrd">if</span> (<span class="kwrd">null</span> != date) {
      SimpleDateFormat yearFormat = <span class="kwrd">new</span> SimpleDateFormat(<span class="str">"yyyy"</span>);
      SimpleDateFormat monthFormat = <span class="kwrd">new</span> SimpleDateFormat(<span class="str">"MM"</span>);
      SimpleDateFormat dayFormat = <span class="kwrd">new</span> SimpleDateFormat(<span class="str">"dd"</span>);
      to.setAfmYear(yearFormat.format(date));
      to.setAfmMonth(monthFormat.format(date));
      to.setAfmDay(dayFormat.format(date));
    }
    SimpleDateFormat format = <span class="kwrd">new</span> SimpleDateFormat(<span class="str">"yyyy-MM-dd"</span>);
    appPo.setAfmdate(format.parse(appForm.getAfmYear() + <span class="str">"-"</span> +
                                  appForm.getAfmMonth() + <span class="str">"-"</span> +
                                  appForm.getAfmDay()));
</span>