自定义标签之带属性的自定义标签

如何创建一个带属性的自定义标签呢?

首先我们要创建一个类继承SimpleTagSupport

 

package clss3g.web.tag;

import java.io.IOException;
import java.util.Date;

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

public class LoopOutTag extends SimpleTagSupport {
private int times;
	
	private Date date;
	
	public void setDate(Date date) {
		this.date = date;
	}//我们设置的日期参数

	public void setTimes(int times) {
		this.times = times;
	}//循环次数参数

	public void doTag() throws JspException, IOException {
				
		for(int i=0; i<times; i++){
			this.getJspBody().invoke(null);
		}
		
		this.getJspContext().getOut().write(date.toString());
	}
	
}

再创建dtd文件,写出Tag标签和处理标签的方法相结合(一个标签对应一个处理方法)

<?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">
    
    <description>there are custom tags of class3g</description>
    <tlib-version>1.0</tlib-version>
    <short-name>class3g</short-name>
    <uri>http://www.class3g.com</uri>
    
     <tag>
        <description>demo1</description>
        <name>loopOut</name>
        <tag-class>clss3g.web.tag.LoopOutTag</tag-class>
        <body-content>scriptless</body-content>
        <attribute>
        	<name>times</name>
        	<required>true</required>
        	<rtexprvalue>true</rtexprvalue>
        </attribute>
		<attribute>
        	<name>date</name>
        	<required>true</required>
        	<rtexprvalue>true</rtexprvalue>
        </attribute>        
    </tag>
    
    
   
</taglib>


之后在JSP文件中使用自定义标签

 

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib uri="http://www.class3g.com" prefix="class3g"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'demo1.jsp' starting page</title>
    
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->

  </head>
  
  <body> 
    This is my JSP page. <br>
   <class3g:loopOut date="<%=new Date() %>" times="10">see?<br/></class3g:loopOut>//使用自定义标签时注意在调用日期函数时记得写表达式  </body>
</html>


最后我们就可以在浏览器中检验一下我们的成果啦

浏览器中输入:http://localhost:8080/20111109/demo1.jsp

效果如下:

This is my JSP page.
see?
see?
see?
see?
see?
see?
see?
see?
see?
see?
Wed Nov 09 16:20:41 CST 2011

 


 

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