jsp自定义标签自学笔记（一）
jsp的自定义标签库有着较好的代码复用性，而且可以使整个页面简洁、美观。使用起来非常方便。下面就动手实现一个简单的“hello world”标签。
1、实现自定义标签可以继承javax.servlet.jsp.tagext.TagSupport类，重写该类方法。代码如下：
package fox.tags.hello;import java.io.IOException;import javax.servlet.jsp.JspException;import javax.servlet.jsp.JspWriter;import javax.servlet.jsp.tagext.TagSupport;public class HelloTag extends TagSupport{@Overridepublic int doStartTag() throws JspException {JspWriter out=this.pageContext.getOut();try{out.write("hello world !");//页面中显示的内容}catch(IOException e){e.printStackTrace();}return this.SKIP_BODY;//不包含主体内容}}<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.2//EN" "http://java.sun.com/dtd/web-jsptaglibrary_1_2.dtd"><taglib> <tlib-version>1.0</tlib-version> <jsp-version>1.2</jsp-version> <short-name>shortname</short-name> <tag> <name>hello</name> <tag-class>fox.tags.hello.HelloTag</tag-class> </tag></taglib>
<?xml version="1.0" encoding="UTF-8"?><web-app version="2.5" 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-app_2_5.xsd"> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> <jsp-config> <taglib> <taglib-uri>/hello-tags</taglib-uri> <taglib-location>/WEB-INF/tld/hello.tld</taglib-location> </taglib> </jsp-config></web-app>
<%@ page language="java" import="java.util.*" pageEncoding="ISO-8859-1"%><%@ taglib prefix="f" uri="/hello-tags" %><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> </head> <body> <f:hello></f:hello> </body></html>