自定义Struts2简单标签

我以获取当前时间的标签为例，开发一个自定义的标签bin:currentTime。操作步骤如下：

一、首先要定义一个标签处理类。

[java]
package org.binbin.tag;

import java.io.IOException;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

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

/**
* 自定义标签
* @author binbin(cn.binbin@qq.com)
* @date 2013-3-28
*/
public class TimeTag extends TagSupport
{
    private static final long serialVersionUID = 6918846280074418825L;

    @Override
    public int doStartTag() throws JspException
    {
        JspWriter out = this.pageContext.getOut();

        //定义时间输出格式
        DateFormat df = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
        //获取当前时间的指定格式字符串
        String str = df.format(new Date());

        try
        {
            //输出当前时间字符串到页面
            out.print(str);
        } catch (IOException e)
        {
            //如果出现异常，当前程序无法处理，所以重新抛出一个运行时异常
            throw new RuntimeException(e);
        }
        return super.doStartTag();
    }
}

package org.binbin.tag;

import java.io.IOException;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

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

/**
* 自定义标签
* @author binbin(cn.binbin@qq.com)
* @date 2013-3-28
*/
public class TimeTag extends TagSupport
{
private static final long serialVersionUID = 6918846280074418825L;

    @Override
    public int doStartTag() throws JspException
    {
        JspWriter out = this.pageContext.getOut();

        //定义时间输出格式
        DateFormat df = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
        //获取当前时间的指定格式字符串
        String str = df.format(new Date());

        try
        {
            //输出当前时间字符串到页面
            out.print(str);
        } catch (IOException e)
        {
            //如果出现异常，当前程序无法处理，所以重新抛出一个运行时异常
            throw new RuntimeException(e);
        }
        return super.doStartTag();
    }
}
二、然后在WEB-INF目录下添加一个标签库定义文件bin.tld

[html]
<?xml version="1.0" encoding="UTF-8" ?>
<taglib xmlns="http://java.sun.com/xml/ns/j2ee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"
    version="2.0">
    <tlib-version>1.0</tlib-version>
    <short-name>bin</short-name>
    <uri>/bin-tags</uri>

    <tag>
        <name>currentTime</name>
        <tag-class>org.binbin.tag.TimeTag</tag-class>
        <body-content>empty</body-content>
    </tag>
</taglib>

<?xml version="1.0" encoding="UTF-8" ?>
<taglib xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"
version="2.0">
<tlib-version>1.0</tlib-version>
<short-name>bin</short-name>
<uri>/bin-tags</uri>

<tag>
  <name>currentTime</name>
  <tag-class>org.binbin.tag.TimeTag</tag-class>
  <body-content>empty</body-content>
</tag>
</taglib>
三、在jsp页面中使用该标签

[html]
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<%@ taglib uri="/bin-tags" prefix="bin"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>My JSP '1.jsp' starting page</title>
</head>
<body>
系统当前时间：<bin:currentTime/>
</body>
</html>

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<%@ taglib uri="/bin-tags" prefix="bin"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>My JSP '1.jsp' starting page</title>
</head>
<body>
系统当前时间：<bin:currentTime/>
</body>
</html>

四、运行效果

补充：Web开发 , Jsp ,