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自定义标签之带属性的自定义标签

2011-11-09 16:21 302 查看

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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标签： date stylesheet jsp class string 浏览器

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