Jsp开发自定义标签，自定义标签将字符串转成指定的时间格式显示

import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Calendar;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;
/**
 * 自定义的时间处理标签
 *
 */
public class JSTLDateTag extends TagSupport {
    /**
     * 
     */
    private static final long serialVersionUID = -8683014812426654300L;
    private String value;//对应jstl表达式中的value值
    private String parttern;//对应表达式中的partern指定的时间格式

    public int doStartTag() throws JspException {
        String vv = String.valueOf(value);
        long time = Long.valueOf(vv);
        Calendar c = Calendar.getInstance();
        c.setTimeInMillis(time);
        SimpleDateFormat dateformat = new SimpleDateFormat(parttern);
        String s = dateformat.format(c.getTime());
        try {
            pageContext.getOut().write(s);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return super.doStartTag();
    }

    public String getValue() {
        return value;
    }

    public void setValue(String value) {
        this.value = value;
    }

    public String getParttern() {
        return parttern;
    }

    public void setParttern(String parttern) {
        this.parttern = parttern;
    }


}

<?xml version="1.0" encoding="UTF-8"?>
<taglib>
    <tlib-version>1.1</tlib-version>
    <jsp-version>1.2</jsp-version>
    <short-name>date</short-name>

    <tag>
        <name>stringToDate</name>
        <tag-class>com.xxx.JSTLDateTag</tag-class><!-- 刚才写的那个标签处理类-->
        <attribute>
            <name>value</name>
            <required>true</required>
            <rtexprvalue>true</rtexprvalue>
        </attribute>
        <attribute>
            <name>parttern</name>
            <required>true</required>
            <rtexprvalue>true</rtexprvalue>
        </attribute>
    </tag>
</taglib>

    <jsp-config>
        <taglib>
            <taglib-uri>http://java.sun.com/jsp/jstl/core</taglib-uri>
            <taglib-location>/WEB-INF/tld/c.tld</taglib-location>
        </taglib>
         <!-- 自定义JSTL时间格式化 -->
       <taglib>        
           <taglib-uri>/datetag</taglib-uri> <!-- 注意这里的 ‘/datetag‘,下面就要用到 -->  
           <taglib-location>/WEB-INF/tld/dateformat.tld</taglib-location>            
       </taglib>   
    </jsp-config>

<%@ taglib uri="/datetag" prefix="fmtDate"%>

<fmtDate:stringToDate parttern="yyyy-MM-dd HH:mm:ss" value="${hotContent.createDate}"></fmtDate:stringToDate>