演示JSP中的4个作用域
scope1.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<jsp:useBean id="pagevar" scope="page" class="java.lang.StringBuffer"/>
<jsp:useBean id="requestvar" scope="request" class="java.lang.StringBuffer"/>
<jsp:useBean id="sessionvar" scope="session" class="java.lang.StringBuffer"/>
<jsp:useBean id="appvar" scope="application" class="java.lang.StringBuffer"/>
<!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>演示作用域</title>
</head>
<body>
<%
pagevar.append("page1");
requestvar.append("page1");
sessionvar.append("page1");
appvar.append("page1");
%>
<!-- 请求转发 -->
<jsp:forward page="scope2.jsp"/>
</body>
</html>
scope2.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<jsp:useBean id="pagevar" scope="page" class="java.lang.StringBuffer"/>
<jsp:useBean id="requestvar" scope="request" class="java.lang.StringBuffer"/>
<jsp:useBean id="sessionvar" scope="session" class="java.lang.StringBuffer"/>
<jsp:useBean id="appvar" scope="application" class="java.lang.StringBuffer"/>
<!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>演示作用域</title>
</head>
<body>
<h3>操作结果：</h3>
<hr>
<%
pagevar.append("page2");
requestvar.append("page2");
sessionvar.append("page2");
appvar.append("page2");
%>
<pre>
page = <%=pagevar.toString()%>
request = <%=requestvar.toString()%>
session = <%=sessionvar.toString()%>
app = <%=appvar.toString()%>
</pre>
</body>
</html>
下面来做测试
首先访问scope1.jsp
page = page2 [新页面]
request = page1page2 [同一请求]
session = page1page2 [同一会话]
app = page1page2 [同一应用]
随后把浏览器地址该成scope2.jsp
page = page2 [新页面]
request = page2 [新请求]
session = page1page2page2 [同一会话]
app = page1page2page2 [同一应用]
接着打开一新浏览器窗口访问scope2.jsp
page = page2 [新页面]
request = page2 [新请求]
session = page2 [新会话]
app = page1page2page2page2 [同一应用]
最后不关闭浏览器重新启动服务器，再刷新浏览器
page = page2 [新页面]
request = page2 [新请求]
session = page2page2 [同一会话]
app = page2 [新应用]