JavaBean四个作用域范围的详解
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2024-04-01 19:52:40
javabean四个作用域范围的详解
一 说明
使用usebeans的scope属性可以用来指定javabean的作用范围。
二 四个作用范围...
javabean四个作用域范围的详解
一 说明
使用usebeans的scope属性可以用来指定javabean的作用范围。
二 四个作用范围
三 代码
1、login.jsp
<%@ page language="java" import="java.util.*" contenttype="text/html; charset=utf-8" %>
<%
string path = request.getcontextpath();
string basepath = request.getscheme()+"://"+request.getservername()+":"+request.getserverport()+path+"/";
%>
<!doctype html public "-//w3c//dtd html 4.01 transitional//en">
<html>
<head>
<base href="<%=basepath%>" rel="external nofollow" rel="external nofollow" rel="external nofollow" >
<title>my jsp 'login.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" rel="external nofollow" rel="external nofollow" rel="external nofollow" >
-->
</head>
<body>
<h1>系统登录</h1>
<hr>
<form name="loginform" action="dologin.jsp?mypass=999999" method="post">
<table>
<tr>
<td>用户名：</td>
<td><input type="text" name="username" value=""/></td>
</tr>
<tr>
<td>密码：</td>
<td><input type="password" name="password" value=""/></td>
</tr>
<tr>
<td colspan="2" align="center"><input type="submit" value="登录"/></td>
</tr>
</table>
</form>
</body>
</html>
2、dologin.jsp
<%@ page language="java" import="java.util.*" contenttype="text/html; charset=utf-8"%>
<%
string path = request.getcontextpath();
string basepath = request.getscheme()+"://"+request.getservername()+":"+request.getserverport()+path+"/";
%>
<!doctype html public "-//w3c//dtd html 4.01 transitional//en">
<html>
<head>
<base href="<%=basepath%>" rel="external nofollow" rel="external nofollow" rel="external nofollow" >
<title>my jsp 'dologin.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" rel="external nofollow" rel="external nofollow" rel="external nofollow" >
-->
</head>
<body>
<jsp:usebean id="myusers" class="com.po.users" scope="page"/>
<h1>setproperty动作元素</h1>
<hr>
<!--根据表单自动匹配所有的属性 -->
<%--
<jsp:setproperty name="myusers" property="*"/>
--%>
<!--根据表单匹配所有部分的属性 -->
<%--
<jsp:setproperty name="myusers" property="username"/>
--%>
<!--根表单无关，通过手工赋值给属性 -->
<%--
<jsp:setproperty name="myusers" property="username" value="lisi"/>
<jsp:setproperty name="myusers" property="password" value="888888"/>
--%>
<!--通过url传参数给属性赋值 -->
<jsp:setproperty name="myusers" property="username"/>
<jsp:setproperty name="myusers" property="password" param="mypass"/>
<!-- 使用传统的表达式方式来获取用户名和密码 -->
<%--
用户名：<%=myusers.getusername() %><br>
密码：<%=myusers.getpassword() %><br>
--%>
<!-- 使用getproperty方式来获取用户名和密码 -->
用户名：<jsp:getproperty name="myusers" property="username"/> <br>
密码：<jsp:getproperty name="myusers" property="password"/><br>
<br>
<br>
<a href="testscope.jsp" rel="external nofollow" >测试javabean的四个作用域范围</a>
<%
request.getrequestdispatcher("testscope.jsp").forward(request, response);
%>
</body>
</html>
3、testscope.jsp
<%@ page language="java" import="java.util.*"
contenttype="text/html; charset=utf-8"%>
<%@ page import="com.po.users"%>
<%
string path = request.getcontextpath();
string basepath = request.getscheme() + "://"
+ request.getservername() + ":" + request.getserverport()
+ path + "/";
%>
<!doctype html public "-//w3c//dtd html 4.01 transitional//en">
<html>
<head>
<base href="<%=basepath%>" rel="external nofollow" rel="external nofollow" rel="external nofollow" >
<title>my jsp 'testscope.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" rel="external nofollow" rel="external nofollow" rel="external nofollow" >
-->
</head>
<body>
<h1>javabean的四个作用域范围</h1>
<hr>
<jsp:usebean id="myusers" class="com.po.users" scope="page" />
用户名：<jsp:getproperty name="myusers" property="username" /><br> 密码：<jsp:getproperty
name="myusers" property="password" /><br>
<!-- 使用内置对象获取用户名和密码 -->
<hr>
<%--
用户名：<%=((users)application.getattribute("myusers")).getusername()%><br>
密码：<%=((users)application.getattribute("myusers")).getpassword() %><br>
--%>
<%--
用户名：<%=((users)session.getattribute("myusers")).getusername()%><br>
密码：<%=((users)session.getattribute("myusers")).getpassword() %><br>
--%>
<%--
用户名：<%=((users)request.getattribute("myusers")).getusername()%><br>
密码：<%=((users)request.getattribute("myusers")).getpassword() %><br>
--%>
<%
string username = "";
string password = "";
if (pagecontext.getattribute("myusers") != null) {
username = ((users) pagecontext.getattribute("myusers"))
.getusername();
password = ((users) pagecontext.getattribute("myusers"))
.getpassword();
}
%>
用户名：<%=username%><br> 密码：<%=password%><br>
</body>
</html>
四 测试结果
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