<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <%@taglib prefix="t" uri="/WEB-INF/tag.tld"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> </head> <body> <% request.setAttribute("user", "user"); %> <t:if test="${user==null }">还没有登录</t:if> <t:if test="${user!=null }">欢迎您： ${user }</t:if> </body> </html>
<?xml version="1.0" encoding="UTF-8" ?> <!-- 文件名 /WEB-INF/referer.tld --> <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>anyName</short-name><!-- 这个值可以任意设置 --> <uri>anyUri</uri><!-- 这个Uri可以任意设置，但是不要与别的 .tld 文件相同 --> <tag> <name>if</name> <tag-class>de.bvb.web.tag.IfTag</tag-class> <body-content>scriptless</body-content> <attribute> <name>test</name> <required>true</required> <rtexprvalue>true</rtexprvalue> </attribute> </tag> </taglib>
package de.bvb.web.tag; import java.io.IOException; import javax.servlet.jsp.JspException; import javax.servlet.jsp.tagext.SimpleTagSupport; public class IfTag extends SimpleTagSupport { private boolean test; public void setTest(boolean test) { this.test = test; } @Override public void doTag() throws JspException, IOException { if (test) { this.getJspBody().invoke(null); // 执行标签体 } } }