关于response对象的转发和重定向
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2022-04-20 22:20:35
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Response对象的转发和重定向如何理解
- 转发( forward) 和重定向( redirect )的·区别方式就在于他们的
转发形式。forward的转发方式是直接转发的，而rediect则为间接转发。 - 直接转发方式定义：客户端和浏览器只发出一次请求, Servlet、 HTML、JSP或其它信息资源,由第二个信息资源响应该请求,在请求对象request中,保存的对象对于每个信息资源是共享的。
间接转发方式定义：实际是两次请求,服务器端在响应第一次请求的时候 ,让浏览器再向另外一个URL发出请求,从而达到转发的目的。
写作
写作代码如下：
1：登录代码如下
<%@ 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 '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">
</head>
<body>
<form action="loginServlet.jsp" method="post">
用户名
<input type="text" name="userName" />
</br>
密码
<input type="text" name="pwd" />
</br>
<input type="submit" value="登录" />
</form>
</body>
</html>
2：创建登录的代码
<%@ 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 'loginServlet.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">
</head>
<body>
<%
String pwd = request.getParameter("pwd");
String userName = request.getParameter("userName");
if ("zhangsan".equals(userName) && "123".equals(pwd)) {
response.sendRedirect("success.jsp");
}
%>
</body>
</html>
3：打开服务器登录成功的代码
<%@ 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 'success.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>
<h1>
登录成功!
</h1>
</body>
</html>
4：在浏览器中出入localhost：8080+自己的项目名和包名
显示界面如下
5：进行下一步操作并输入正确格式的账号密码跳转至登录成功界面。当用户名密码正确时，loginServlet服务器做出一次响应告诉客户端需要跳转到登陆成功界面，接着客户端对success.jsp做出一次请求，最终得到success.jsp页面登录成功的响应。
6：转发界面的登录代码
<%@ 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 '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">
</head>
<body>
<%
String message = "";
message = (String) request.getAttribute("message");
if (message == null)
message = "";
%>
<form action="loginServlet.jsp" method="post">
用户名
<input type="text" name="userName" />
</br>
密码
<input type="text" name="pwd" />
<span style="color: red"><%=message%></span>
</br>
<input type="submit" value="登录" />
</form>
</body>
</html>
7：服务代码
<%@ 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 'loginServlet.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">
</head>
<body>
<%
//接收客户端发送的用户名，密码
String pwd = request.getParameter("pwd");
String userName = request.getParameter("userName");
//我们设定用户名为：zhangsan,密码为：123
if ("zhangsan".equals(userName) && "123".equals(pwd)) {
//当登录成功时跳转到登陆成功界面
//发送重定向响应
response.sendRedirect("success.jsp");
} else {
//当登陆失败时跳转到登录页面并反馈错误信息
//转发
//设置转发内容
request.setAttribute("message", "密码错误!");
//调用getRequestDispacther()方法，把请求转发给login.jsp
request.getRequestDispatcher("login.jsp").forward(request,
response);
}
%>
</body>
</html>
这次我们在浏览器中输入错误的账号名密码点击登录，就会出现反馈信息。一个做请求操作，一个做响应操作。
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