开发和使用自定义标签程序有三个步骤：
1.开发标签实现类
2.编写标签描述，这个描述通常是以.tld结尾的文件
3.在web.xml中指定标签库的引用
开发实现：
package com.rain.tag;
import Java.io.IOException;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspTagException;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.Tag;
public class HelloTag implements Tag {
private PageContext pageContext;
private Tag parent;
public HelloTag(){
super();
}
public int doEndTag() throws JspException {
// TODO Auto-generated method stub
try{
pageContext.getOut().write("Hello World! 你好");
}catch(IOException e){
throw new JspTagException("IO Error:"+e.getMessage());
}
return EVAL_PAGE;
}
public int doStartTag() throws JspException {
// TODO Auto-generated method stub
return SKIP_BODY; //返回SKIP_BODY，表示不计算标签体
}
public Tag getParent() {
// TODO Auto-generated method stub
return this.parent;
}
public void release() {
// TODO Auto-generated method stub
}
public void setPageContext(PageContext arg0) {
// TODO Auto-generated method stub
this.pageContext=arg0;
}
public void setParent(Tag arg0) {
// TODO Auto-generated method stub
this.parent=arg0;
}
}
编写标签库描述
<?xml version="1.0" encoding="UTF-8" ?>
<taglib xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee web-jsptaglibrary_2_0.xsd"
version="2.0">
<description>A tag library exercising SimpleTag handlers.</description>
<tlib-version>1.0</tlib-version>
<short-name>examples</short-name>
<uri>/demotag</uri>
<description>JSP应用开发</description>
<tag>
<description>Outputs Hello,World</description>
<name>hello_int</name>
<tag-class>com.rain.tag.HelloTag</tag-class>
<body-content>empty</body-content>
</tag>
</taglib>
使用自定义标签
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app>
<taglib>
<taglib-uri>/demotag</taglib-uri>
<taglib-location>/WEB-INF/mytag.tld</taglib-location>
</taglib>
</web-app>
<%@ page language="Java" contentType="text/html; charset=UTF-8"%>
<%@ taglib uri="/demotag" prefix="hello" %>
<html>
<head>
<title>Insert title here</title>
</head>
<body>
<p>以下的内容是从Taglib中显示的：</p>
<p><i><hello:hello_int/></i></p>
</body>
</html>
本实例是实现Tag接口，但为了在开发中方便简单，一般直接继承TagSupport类，只覆盖doStartTag和doEndTag两个方法就可以。TagSupport是Tag的子类。
posted on 2007-01-22 11:53
周锐 阅读(1395)
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