JSP 自定义标签例子(BodyTagSupport)

1.在WEB-INF下新建一个stag.tld文件

<?xml version="1.0" encoding="ISO-8859-1" ?>
<!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag 
Library 1.2//EN"
"http://java.sun.com/dtd/web-jsptaglibrary_1_2.dtd">
<taglib>
        <tlibversion>1.0</tlibversion>
        <jspversion>1.1</jspversion>
        <shortname>tbl</shortname>
   <tag>
        <name>stag</name>
        <tagclass>test.MyTag</tagclass>
        <bodycontent>JSP</bodycontent>
        <info>To Convert in Upper case tag</info>
   </tag>
</taglib>

package test;

import javax.servlet.*;
import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;
import java.util.*;
import java.io.*;

public class MyTag extends BodyTagSupport 
{
    public int doAfterBody() throws JspException {
      try {
         BodyContent bodycontent = getBodyContent();
         System.out.println("---------bodycontent---------:"+bodycontent);
         String body = bodycontent.getString();
         System.out.println("---------body---------:"+body);
         JspWriter out = bodycontent.getEnclosingWriter();
         System.out.println("---------out---------:"+out);
         if(body != null) {
            out.print(body.toUpperCase());
         }
      } catch(IOException ioe) {
         throw new JspException("Error:"+ioe.getMessage());
      }
      return SKIP_BODY;
  }

    @Override
    public int doEndTag() throws JspException {
        System.out.println("---------doEndTag()----------");
        return super.doEndTag();
    }

    @Override
    public void doInitBody() throws JspException {
        System.out.println("---------doInitBody()----------");
        super.doInitBody();
    }

    @Override
    public int doStartTag() throws JspException {
        System.out.println("---------doStartTag()----------");
        return super.doStartTag();
    }
}

<%@ page language="java" import="java.util.*" pageEncoding="GBK"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<%@ taglib uri="/WEB-INF/stag.tld" prefix="tbl" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'index.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>
    <tbl:stag>
        hello ! BodyTagSupport例子
    </tbl:stag>
  </body>
</html>

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原文地址：https://www.cnblogs.com/zendwang/p/2607768.html