JSP自定义标签_用简单标签实现控制标签体是否执行

什么都不说,直接上代码:

import java.io.IOException;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.JspFragment;
import javax.servlet.jsp.tagext.SimpleTagSupport;

//控制标签体是否执行
public class SimpleTagDemo1 extends SimpleTagSupport {
    //简单标签使用这个方法完成所有业务逻辑
    @Override
    public void doTag() throws JspException, IOException {
        //得到代表标签体的JspFragment
        JspFragment jf = this.getJspBody();
        //PageContext pageContext = (PageContext) this.getJspContext(); 
//jf.invoke(pageContext.getOut());
        jf.invoke(null); //这个方法等同于上面注释两行代码.
        
    }

    
    
}

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@taglib uri="/simpleitcast" prefix="itcast" %>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>用简单标签实现控制标签体是否执行</title>
  </head>
  
  <body>
  
  <itcast:demo1>
      xxxx
  </itcast:demo1>
  
  </body>
</html>

 <description>A tag library exercising SimpleTag handlers.</description>
    <tlib-version>1.0</tlib-version>
    <short-name>SimpleTagLibrary</short-name>
    <uri>/simpleitcast</uri>
    
    
    <tag>
        <name>demo1</name>  <!-- 为标签处理器类配一个标签名 -->
        <tag-class>cn.itcast.web.simpletag.SimpleTagDemo1</tag-class>
        <body-content>scriptless</body-content>
    </tag>

JSP自定义标签_用简单标签实现控制标签体是否执行

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