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JSP implicit object servlet object

2022-07-26 08:00:00 【Super Qi】

jsp Implicit objects -Servlet object

pageContent object

1. effect

You can get the current jsp All implicit objects of the page . Scope of action ： Current page

2. Method

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* Be careful

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3. example （session object 、pageContent object 、application The difference between the three objects ）

<%@ page contentType="text/html;charset=UTF-8" language="java" pageEncoding="UTF-8" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<%
   if(pageContext.getAttribute("pCount")==null){
       pageContext.setAttribute("pCount",new Integer(0));    //pageContent object 
   }
   if(session.getAttribute("sCount")==null){
       session.setAttribute("sCount",new Integer(0));   //session object 
   }
   if(application.getAttribute("aCount")==null){
       application.setAttribute("aCount",new Integer(0));  //application object 
   }
%>
<%
    Integer c1 = (Integer)pageContext.getAttribute("pCount");
    pageContext.setAttribute("pCount",new Integer(c1.intValue()+1));  // In the original pageContent add 1
    Integer c2 = (Integer)session.getAttribute("sCount");
    session.setAttribute("sCount",new Integer(c2.intValue()+1));  // In the original pageContent add 1
    Integer c3 = (Integer)application.getAttribute("aCount");
    application.setAttribute("aCount",new Integer(c3.intValue()+1));  // In the original pageContent add 1
%>
<b> Page count ：</b><%=pageContext.getAttribute("pCount")+"<br>" %>
<b> Session count ：</b><%=session.getAttribute("sCount")+"<br>" %>
<b> Application count ：</b><%=application.getAttribute("aCount")+"<br>" %>
<b> Time ：</b><%=new java.sql.Time(System.currentTimeMillis()) %>
</body>
</html>