JSP 自定义标签库实现步骤
java类：
package com.Aaron.test;
import java.util.Properties;
import javax.servlet.http.HttpSession;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspTagException;
import javax.servlet.jsp.tagext.TagSupport;
public class MessageTag extends TagSupport {
private String key;
public MessageTag(){
}
@Override
public int doEndTag() throws JspException {
try {
Properties ps = (Properties)pageContext.getAttribute("ps",pageContext.APPLICATION_SCOPE);
Properties ps_zh = (Properties)pageContext.getAttribute("ps_zh",pageContext.APPLICATION_SCOPE);
HttpSession session = pageContext.getSession();
String language = (String)session.getAttribute("language");
String message = null;
if(language != null && language.equals("Chinese")){
message = ps_zh.getProperty(key);
}else{
message = ps.getProperty(key);
}
pageContext.getOut().print(message);
} catch (Exception e) {
throw new JspTagException(e.getMessage());
}
return SKIP_BODY;
}
@Override
public void release() {
super.release();
}
public String getKey() {
return key;
}
public void setKey(String key) {
this.key = key;
}
}
**************************************************
tld标签：
<?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>mytaglib</shortname>
<uri>/mytaglib</uri>
<tag>
<name> message</name>
<tagclass>com.Aaron.test.MessageTag </tagclass>
<bodycontent>empty </bodycontent>
<info>produce message by key</info>
<attribute>
<name>key</name>
<required>true</required>
</attribute>
</tag>
</taglib>
******************************************************
web.xml:
<taglib>
<taglib-uri>/mytaglib</taglib-uri>
<taglib-location>/WEB-INF/mytaglib.tld</taglib-location>
</taglib>
***************************************************
jsp 页面：
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="ISO-8859-1" %>
< %@taglib uri="/mytaglib" prefix="msg" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd ">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title><msg:message key="hello.hello"/></ title>
</head>
<body>
<%
String language = request.getParameter("language");
language = language == null ? "English" : language;
session.setAttribute("language",language);
%>
<msg:message key="login.user"/>:<input type="text"/>
<br>
<msg:message key="login.password"/>:<input type="password"/>
<br>
<msg:message key="login.submit"/>:<input type="submit"/>
</body>
</html>