第八次作业
1.登陆
输入用户名密码，判断用户名和密码相同，登陆成功，session中保存用户的用户名，进入主页main.jsp，
主页有一个退出按钮，点击，回到登陆页login.jsp。要求：退出登录后，如果在浏览器直接输入主页main.jsp，
访问不了，直接跳到登陆页。
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
</head>
<script type="text/javascript">
function v() {
if (loginForm.uname.value=="") {
alert("账号不能为空！");
return;
}
if (loginForm.password.value=="") {
alert("密码不能为空！");
return;
}
loginForm.submit();
}
</script>
<body>
<form name="loginForm" action="m.jsp" method="post">
账号：<input type="text" name="uname"><br>
密码：<input type="password" name="password"> <br>
<input type="submit" value="登录" onclick="v()">
</form>
</body>
</html>
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
</head>
<body>
<%
request.setCharacterEncoding("utf-8");
String uname = request.getParameter("uname");
String password = request.getParameter("password");
if (uname.equals(password)) {
session.setAttribute("uname", uname);
request.getRequestDispatcher("J.jsp").forward(request, response);
} else {
response.sendRedirect("q.jsp");
}
%>
</body>
</html>
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
</head>
<body>
<%
String uname=(String)session.getAttribute("uname");
//如果他是空，说明没登陆，直接访问该页面了
if(uname==null)
response.sendRedirect("index.jsp");
%>
欢迎<br>
<a href="n.jsp">退出登录</a> <br>
</body>
</html>
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
</head>
<%String src=request.getParameter("id"); %>
<body>
登陆失败，请重试
<%
response.setHeader("refresh", "5;url=index.jsp");
%>
</body>
</html>
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
</head>
<body>
<%
session.invalidate();
response.setHeader("refresh", "5;url=index.jsp");
%>
退出成功!
</body>
</html>
2.购物车
和上一题一起，在main.jsp中做一个购物车，里面显示3个商品名和价格 每一个后面有一个加入购物车按钮，main.jsp中有一个按钮（或者超链接）可以显示购物车。（选作：在购物车中加删除按钮删除商品）
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>main</title>
</head>
<body>
<h1>登陆成功！</h1>
<%
String uname = (String) session.getAttribute("uname");
//如果他是空，说明没登陆，直接访问该页面了
if (uname == null)
response.sendRedirect("login.jsp");
%>
<form action="show.jsp" method="post">
商品：<br> <br>
苹果 5.45<input type="checkbox" name="item" value="苹果">加入购物车 <br>
梨 4.34 <input type="checkbox" name="item" value="梨"> 加入购物车 <br>
香蕉 4.56<input type="checkbox" name="item" value="香蕉"> 加入购物车<br><br>
<input type="submit" value="加入购物车">
</form>
<form name="form1" action="logout.jsp" method="post">
<input type="submit" value="退出登录">
</form>
</body>
</html>
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>show</title>
</head>
<body>
<%
request.setCharacterEncoding("utf-8");
String itemName[]=request.getParameterValues("item");
if(itemName==null){
out.print("未添加购物车");
}
else{
for(int i=0;i<itemName.length;i++){
out.print("("+(i+1)+")"+itemName[i]+"<br>");
}
}
%>
</body>
</html>
