自定义标签开发步骤
1）编写一个普通的java类，继承SimpleTagSupport类，叫标签处理器类
package gz.itcast; 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; } public void doTag() throws JspException, IOException { // TODO Auto-generated method stub if(test){ this.getJspBody() .invoke(null); } } }
2）在web项目的WEB-INF目录下建立itcast.tld文件，这个tld叫标签库的声明文件。（参考核心标签库的tld文件）
<?xml version="1.0" encoding="UTF-8" ?> <taglib xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd" version="2.1"> <tlib-version>1.1</tlib-version> <short-name>itcast</short-name> <uri>http://gz.itcast.cn</uri> <tag> <name>if</name> <tag-class>gz.itcast.iftag</tag-class> <body-content>scriptless</body-content> <attribute> <name>test</name> <required>true</required> <rtexprvalue>true</rtexprvalue> </attribute> </tag> </taglib>
3） 在jsp页面的头部导入自定义标签库
<%@taglib uri="http://gz.itcast.cn" prefix="itcast"%>
4） 在jsp中使用自定义标签
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> <%@taglib uri="http://gz.itcast.cn" prefix="itcast" %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> </head> <body> <itcast:if test="${10>5}">条件成立</itcast:if> </body> </html>