如何在JavaWeb程序中使用自定义标签(tag、tld两种)

tld定义格式

<?xml version="1.0" encoding="ISO-8859-1" ?><!DOCTYPE taglibPUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.2//EN""http://java.sun.com/dtd/web-jsptaglibrary_1_2.dtd"><taglib><!--定义标签版本库--><tlib-version>1.0</tlib-version><!--定义jsp版本库--><jsp-version>1.2</jsp-version><short-name>Cms Tag</short-name><description><!--标签描述--->A simple appbase tag library</description><tag><name>page</name><!--tag的名字--><tag-class>com.cms.common.tag.PageTag</tag-class><!--tag对应的java类的名字--><body-content>empty</body-content><!--关于body-content 有三个值可选;empty：标签体必须为空;jsp：标签由其他jsp元素组成比如标签中含有<%=attributeName%>的jsp元素,那么此时body-content的值就是实际attributeName传入的值;tagdependent:有标签解释不带jsp转换（这个深入的含义不太了解）--><attribute><!---这里表示的是这个tag的一个参数--><name>cmsform</name><!--这个参数的名字--><required>true</required><!--是否是必填选项--><rtexprvalue>true</rtexprvalue><!--这个参数的值是否可以写入，换句话说 就是这个参数是否可以动态赋值--></attribute></tag></taglib>

定义Tag对应类

此类必须重写doStartTag以及doEndTag方法

/** *  */package com.cms.common.tag;import javax.servlet.jsp.JspException;import javax.servlet.jsp.JspWriter;import javax.servlet.jsp.tagext.TagSupport;/** * @author louisliao * */public class DemoViewTag extends TagSupport {/** *  */private static final long serialVersionUID = 1L;private String cmsform = "";public String getCmsForm() {return cmsform ;}public void setCmsForm(String cmsform ) {this.cmsform = cmsform ;}/** *  */public DemoViewTag() {// TODO Auto-generated constructor stub}public int doStartTag(){return super.SKIP_BODY;}public int doEndTag() throws JspException{JspWriter writer=pageContext.getOut();try {writer.print("这是我的标签示例<br/>"+"cmsform :"+this.cmsform);} catch (Exception e) {// TODO: handle exceptione.printStackTrace();}return super.EVAL_PAGE;}}

在web.xml中加入taglib对应文件配置

如：

<taglib><taglib-uri>http://mytag.sf.net</taglib-uri><taglib-location>/WEB-INF/mytag.tld</taglib-location></taglib>

这样就表示了http://mytag.sf.net对应WEB-INF/mytag.tld文件

 

在Jsp页面中引用

如：

<%@ taglib uri="http://mytag.sf.net" prefix="myTag"%>

 

在Jsp页面中使用

<myTag:exname1><myTag:exname1>

 

示例：

定义myTag.tld标签文件

<?xml version="1.0" encoding="utf-8"?><!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.1//EN"  "http://java.sun.com/j2ee/dtds/web-jsptaglibrary_1_1.dtd"><taglib><tlibversion>1.0</tlibversion><jspversion>1.1</jspversion><shortname>MyJSPTag Library</shortname><uri>http://mytag.sf.net</uri><info>我的示例标签库</info><tag><name>demo.Viewport</name><tagclass>com.myapp.web.tag.DemoViewTag</tagclass><bodycontent>JSP</bodycontent><info>demo.Viewport标签</info><attribute><name>northTitle</name><required>true</required><rtexprvalue>true</rtexprvalue></attribute><attribute><name>westTitle</name><required>true</required><rtexprvalue>true</rtexprvalue></attribute></tag></taglib>

定义标签类

/** *  */package com.myapp.web.tag;import javax.servlet.jsp.JspException;import javax.servlet.jsp.JspWriter;import javax.servlet.jsp.tagext.TagSupport;/** * @author louisliao * */public class DemoViewTag extends TagSupport {/** *  */private static final long serialVersionUID = 1L;private String northTitle = "";private String westTitle = "";public String getNorthTitle() {return northTitle;}public void setNorthTitle(String northTitle) {this.northTitle = northTitle;}public String getWestTitle() {return westTitle;}public void setWestTitle(String westTitle) {this.westTitle = westTitle;}/** *  */public DemoViewTag() {// TODO Auto-generated constructor stub}public int doStartTag(){return super.SKIP_BODY;}public int doEndTag() throws JspException{JspWriter writer=pageContext.getOut();try {writer.print("这是我的标签示例<br/>westTitle："+this.westTitle+"<br/>northTitle:"+this.northTitle);} catch (Exception e) {// TODO: handle exceptione.printStackTrace();}return super.EVAL_PAGE;}}

web.xml添加配置

<taglib><taglib-uri>http://mytag.sf.net</taglib-uri><taglib-location>/WEB-INF/mytag.tld</taglib-location></taglib>

测试页面

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%><%@ taglib uri="http://mytag.sf.net" prefix="myTag"%> <%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 'tagtldDemo.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>    <myTag:demo.Viewport northTitle="南" westTitle="西"></myTag:demo.Viewport>  </body></html>