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JSP之request对象

2016-02-29 15:13 288 查看

在请求转发时，我们需要把一些数据传递到转发后的页面进行处理。这时就需要使用request对象的setAttribute（）方法将数据保存到request范围内的变量中。

示例：创建index.jsp文件，使用Java中的try……catch语句捕获异常，将数据保存到request范围内的变量中：

<%@ page language="java" import="java.util.*" pageEncoding="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%>">
<title>My JSP 'index.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">
-->
</head>

<body>
<%
try{
int a=1;
int b=0;
request.setAttribute("result", a/b);
}catch(Exception e){
request.setAttribute("result", "很抱歉，页面发生错误！");
}
%>
<jsp:forward page="MyJsp.jsp"></jsp:forward>
</body>
</html>

　　

然后用 <jsp:forward>动作将指令转发到MyJsp.jsp页面：

<%@ page language="java" import="java.util.*" pageEncoding="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%>">

<title>My JSP 'MyJsp.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">
-->

</head>

<body>
<%String message=request.getAttribute("result").toString(); %>
<%=message %>
</body>
</html>

run:

很抱歉，页面发生错误！

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