JSP编写定制标签之处理属性

xiaoxiao2021-02-28 109

实现SimpleTag接口或者继承SimpleTagSupport的标签处理器可以带属性，在上一篇文章中我实现SimpleTag接口实现了定制标签，这次我将继承SimpleTagSupport为标签添加属性。编写类 public class Attribute extends SimpleTagSupport{ private String header; private String items; public void setHeaerd(String header) { this.header = header; } public void setItems(String items) { this.items = items; } public void doTag() throws IOException{ //首先调用getJspContext()方法获得JSP容器传来的jspContext JspContext jspContext = getJspContext(); //在getJspContext实例中调用getOut()方法，获得一个JspWriter，用它编写给客户端的响应 JspWriter out = jspContext.getOut(); //doGet()方法利用StringTokenizer解析items属性，并将每一项设置成一个表格 out.print("<table style='border:1px solid green'>\n" +"<tr><td><spqan style='font-weight:bold'>" +header+"</span></td></tr>\n"); StringTokenizer tokenizer = new StringTokenizer(items,",");//StringTokenizer根据自定义字符为分界符进行拆分 while (tokenizer.hasMoreTokens()) { String token = tokenizer.nextToken(); out.print("<tr><td>"+token+"</td></tr>\n"); } out.print("</table>"); } }

2.列表内容在tld文件中注册

<?xml version="1.0" encoding="ISO-8859-1"?> <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/web-jsptaglibrary_2_0.xsd" verson="2.0"> <description>Simple tag examples</description> <tlib-version>1.0</tlib-version> <jspversion>2.3</jspversion> <short-name>My First Taglib Example</short-name> <tag> <name>dataFormatter</name> <tag-class>tag.Attribute</tag-class> <body-content>empty</body-content> <attribute> <name>header</name> <required>true</required> </attribute> <attribute> <name>items</name> <required>true</required> </attribute> </tag> </taglib>

在添加在前面的例子用过的tld文件即可

3.测试 jsp文件：

<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%> <%@ taglib uri="/WEB-INF/mytags.tld" prefix="easy" %> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>Test</title> </head> <body> <easy:dataFormatter header="Num" items="1,2,3"/> <easy:dataFormatter header="Alph"> <jsp:attribute name="items"> a,b,c </jsp:attribute> </easy:dataFormatter> </body> </html>

这里使用了两种方法传递属性，一种是一个标签属性，另一种是attribute动作指令。

结果：

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