I learned some tutorials on JSP custom tags on the Internet and implemented a small example myself.
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">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"?> <Tagliblib> <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> <! -- Define Attributes --> <attribute> <Name> pattern </Name> <! -- Attribute name --> <type> string </type> <! -- Property type --> <requried> false </requried> <! -- Required? --> <rtexprvale> false </rtexprvale> <! -- Indicates whether JSP expressions can be used --> </attribute> </Tag> <tag> <Name> iterator </Name> <tagclass> COM. zyujie. util. mytag </tagclass> <bodycontent> JSP </bodycontent> <! -- Define Attributes --> <attribute> <Name> count </Name> <! -- Attribute name --> <type> int </type> <! -- Property type --> <requried> false </requried> <! -- Required? --> <rtexprvale> false </rtexprvale> <! -- Indicates whether JSP expressions can be used --> </attribute> </Tag> </taglib>Implementation class 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 {// execution sequence // dostarttag ()-> setbodycontent ()-> doinitbody ()-> doaftertag ()-> doendt AG () //// if dostarttag () returns eval_body_include, execute the doaftertag () method, // if it returns skip_body, execute the doendtag () method. //// Setbodycontent () method is used to set the content of the label body. If Initialization is required when bodycontent is calculated, /// it is completed in the doinitbody () method. After the label body content is executed, the doafterbody () method will be called // The eval_body_again will be returned in the doaftertag () method to repeatedly execute doaftertag () method //// if the skip_body value is returned, the doendtag () method is executed. //// If the eval_page value is returned in the doendtag () method, other code after the label is executed. //// if the value of skip_page is returned, other code on the page is not executed. 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;} // set the current TAG body @ overridepublic void setbodycontent (bodycontent) {This. bodycontent = bodycontent; system. out. println ("setbodycontent... ");} // You Need to initialize 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;} // The setxx () method public void setcount (INT count) {This. count = count ;}}This completes the implementation of custom tags.
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