jstl long类型数据转换为日期格式

<?xml version="1.0" encoding="UTF-8"?>  
<taglib>  
    <tlib-version>1.0</tlib-version>  
    <jsp-version>1.2</jsp-version>  
  
    <tag>  
        <name>date</name>  
        <tag-class>com.hoolai.pirates.football.util.DateTag</tag-class>          
        <body-content>JSP</body-content>  
        <attribute>  
            <name>value</name>  
            <required>true</required>  
            <rtexprvalue>true</rtexprvalue>  
        </attribute>  
    </tag>  
</taglib>

package com.hoolai.pirates.football.util;

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

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;

public class DateTag extends TagSupport {
    private static final long serialVersionUID = -2312310581852395045L;
    private String value;

    @Override
    public int doStartTag() throws JspException {
        String vv = "" + value;
        long time = Long.valueOf(vv);
        Calendar c = Calendar.getInstance();
        c.setTimeInMillis(time);
        SimpleDateFormat dateformat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        String s = dateformat.format(c.getTime());
        try {
            pageContext.getOut().write(s);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return super.doStartTag();
    }

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

<%@ taglib prefix="lzq" uri="/WEB-INF/lib/tld/datetag.tld"%>  

<td align="left"><input name="endTime" type="text" value="<lzq:date value="${res.endTime}"/>" class="input_bg" /></td>