给出一个Taglib的BODY_BUFFERED，bodyContent的例子

6）BODY_BUFFERED，bodyContent的例子：

有 时你标签对应的java代码会从数据库或其他网络渠道获取数据。这些数据在最终返回jsp显示之前，需要一个过滤修改的过程。比如去掉某些政治敏感的词语 或像本例一样加入一个词语“马克-to-win”。这时就需要你用BODY_BUFFERED技术。顾名思义就是要把你返回jsp显示的body先 buffer一下，放在BodyTagSupport的bodyContent里，你可以随意修改之，最后再返回jsp，但是前提条件是在 doStartTag中的返回值要写成EVAL_BODY_BUFFERED，这样系统就会开辟bodyContent这个Buffer，供你运作。

例 1.2.6：
<%@ page contentType="text/html; charset=GBK" %>
<%@ taglib uri="/WEB-INF/tagExampleLib.tld" prefix="greeter" %>

  
    
        Now 时间 is: <%=new java.util.Date() %>

    
     结束
  

<?xml version="1.0" encoding="ISO-8859-1" ?>
     PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.1//EN"
     "http://java.sun.com/j2ee/dtds/web-jsptaglibrary_1_1.dtd">

    1.0
    1.1
    mark-to-win
   
        Hello
        com.marktowin.HelloWorldTag
   

/*顺序是： 4)doStartTag
4.5) doAfterBody
5)doEndTag*/
package com.marktowin;
import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;
import java.io.*;
public class HelloWorldTag extends BodyTagSupport {
    int count = 2;
    public int doStartTag() {
        System.out.println("doStartTag");
        return EVAL_BODY_BUFFERED;
    }
    public int doAfterBody() {
        System.out.println("doAfterBody.");
        while (count > 0) {
            count--;
            /* EVAL_BODY_AGAIN requires that the body of the tag is evaluated. */
            return EVAL_BODY_AGAIN;
        }
        return SKIP_BODY;
    }

    public int doEndTag() {
        System.out.println("doEndTagqqq");
        /*the following try catch will be no use if you use return BodyTagSupport.EVAL_BODY_INCLUDE,
         but if you use return BodyTagSupport.EVAL_BODY_BUFFERED;, you must use this try catch,
        otherwise, there will be no output from IE, because the former won't use bodyContent. the
         former use "Evaluate body into existing out stream" */
            try{
              if(bodyContent != null) {
                System.out.println("body content qixy is not null");
        /*public JspWriter getEnclosingWriter() Get the enclosing JspWriter.
        writeOut(Writer out) Write the contents of this BodyContent into a Writer.
                 */            

更多内容请见原文，文章转载自：https://blog.csdn.net/qq_44594371/article/details/103183489