JSP之request对象
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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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