網上學習了一些關於jsp自訂標籤的教程，自己實現了一個小例子。
jsp：
<%@ page language="java" import="java.util.*" pageEncoding="ISO-8859-1"%><%@ taglib uri="/WEB-INF/mytag.tld" prefix="cc"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> <title>My JSP 'tagone.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"> </head> <body> <cc:iterator count="10">Hello world jsp taglib !!!</cc:iterator> </body></html>
web.xml：
<?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> <taglib> <taglib-uri>/WEB-INF/mytag.tld</taglib-uri> <taglib-location>/WEB-INF/mytag.tld</taglib-location> </taglib> </web-app>
mytag.tld：
<?xml version="1.0" encoding="UTF-8"?> <taglib> <tlibversion>1.0</tlibversion> <jspversion>1.1</jspversion> <tag> <name>displayOne</name> <tagclass>com.zyujie.util.MyTagOne</tagclass> <bodycontent>empty</bodycontent> </tag> <tag> <name>displayTwo</name> <tagclass>com.zyujie.util.MyTagTwo</tagclass> <bodycontent>empty</bodycontent> <!-- 定義屬性 --> <attribute> <name>pattern</name> <!-- 屬性名稱字 --> <type>String</type> <!-- 屬性類型 --> <requried>false</requried> <!-- 是否必須 --> <rtexprvale>false</rtexprvale> <!-- 表示是否可以使用JSP運算式 --> </attribute> </tag> <tag> <name>iterator</name> <tagclass>com.zyujie.util.MyTag</tagclass> <bodycontent>jsp</bodycontent> <!-- 定義屬性 --> <attribute> <name>count</name> <!-- 屬性名稱字 --> <type>int</type> <!-- 屬性類型 --> <requried>false</requried> <!-- 是否必須 --> <rtexprvale>false</rtexprvale> <!-- 表示是否可以使用JSP運算式 --> </attribute> </tag> </taglib>
實作類別MyTag.java：
package com.zyujie.util;import java.io.IOException;import java.util.Date;import javax.servlet.http.HttpServletRequest;import javax.servlet.jsp.JspException;import javax.servlet.jsp.JspWriter;import javax.servlet.jsp.tagext.BodyContent;import javax.servlet.jsp.tagext.BodyTagSupport;public class MyTag extends BodyTagSupport {//執行順序////doStartTag()->setBodyContent()->doInitBody()->doAfterTag()->doEndTag()////如果doStartTag()返回的是EVAL_BODY_INCLUDE執行doAfterTag()方法,////如果它返回SKIP_BODY就執行doEndTag()方法。////setBodyContent()方法用於設定標籤體內容，如果在計算BodyContent時需要進行一些初始化工作，////則在doInitBody()方法中完成。標籤體內容執行完後，會調用doAfterBody()方法////在doAfterTag()方法中返回EVAL_BODY_AGAIN來重複執行doAfterTag()方法////返回SKIP_BODY值則執行doEndTag()方法。////在doEndTag()方法中返回EVAL_PAGE值,則執行此標籤的後的其它代碼,////返回SKIP_PAGE則不執行此頁面的其它代碼。private int count;private HttpServletRequest reqeust;private JspWriter out;public void init() {reqeust = (HttpServletRequest) pageContext.getRequest();out = pageContext.getOut();}@Overridepublic int doStartTag() throws JspException {init();return this.EVAL_BODY_INCLUDE;}// 設定當前標籤體@Overridepublic void setBodyContent(BodyContent bodyContent) {this.bodyContent = bodyContent;System.out.println("setBodyContent...");}// 需要初始化bodyContent@Overridepublic void doInitBody() throws JspException {System.out.println("init.....");}@Overridepublic int doAfterBody() throws JspException {if (count >= 1) {try {out.println(count);out.println("<Br>");} catch (IOException e) {e.printStackTrace();}count--;return this.EVAL_BODY_AGAIN;} else {return this.SKIP_BODY;}}@Overridepublic int doEndTag() throws JspException {java.text.SimpleDateFormat formater = new java.text.SimpleDateFormat("yyyy-MM-dd");String date = formater.format(new Date());try {out.print(date);} catch (IOException e) {e.printStackTrace();}return this.EVAL_PAGE;}// 必須實現setXX()方法public void setCount(int count) {this.count = count;}}
這樣就完成了自訂標籤的實現了。
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