使用jsp，tomcat实现用户登录注册留言的代码
以下jsp中，未使用样式表对网页进行排版和表单的验证（每个jsp的表单填写的时候应该进行空值与空格的验证，防止提交时出错）
所有错误，链接到error.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>登陆界面</title> </head> <body> 用户登录 <br /> <form action="verify.jsp" method="post"> 用户名<input type="text" name="username" /><br /> 密码<input type="password" name="pwd" /><br /> <input type="submit" /> <a href="register.jsp"><input type="button" value="注册" /></a> </form> </body> </html>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>登陆验证界面</title>
</head>
<body>
<%
//判断输入用户名为空时，跳转至错误页面
if (request.getParameter("username") == null) {
%>
<jsp:forward page="error.jsp" />
<%
}
//取得输入的用户名
String name = new String(request.getParameter("username").getBytes("iso-8859-1"), "utf-8");
//判断用户名是否已经存在，存在的话，继续判断密码是否一致
if (application.getAttribute(name) != null) {
String storeName = application.getAttribute(name).toString();
String[] stores = storeName.split("#");
String inputPwd = request.getParameter("pwd");
String pwd = stores[1];
if (pwd.equals(inputPwd)) {//密码是否一致
String date = stores[2];
session.setAttribute("name", name);
%>
<%=name%>登陆成功
<br /> 注册时间<%=date%><br /> 5秒后跳转至留言界面
<%
response.setHeader("refresh", "5;URL=message.jsp");
%>
<%
}
} else {//否则跳转
%>
登陆失败
<br /> 5秒后跳转至登陆界面<%
response.setHeader("refresh", "5;URL=index.jsp");
%>
<%
}
%>
</body>
</html>
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>注册界面</title> </head> <body> <form method="post" action="success.jsp"> 用户名<input type="text" name="username" /><br /> 密码<input type="password" name="pwd" /><br /> 确认密码<input type="password" /><br /> <input type="submit" value="注册" /><br /> </form> </body> </html>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ page import="java.util.*"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>注册验证界面</title>
</head>
<body>
<%
//判断输入用户名为空时，跳转至错误页面
if (request.getParameter("username") == null) {
%>
<jsp:forward page="error.jsp" />
<%
}
//取得输入的用户名
String name = new String(request.getParameter("username").getBytes("iso-8859-1"), "utf-8");
//取得输入的密码
String pwd = request.getParameter("pwd");
//取得服务器中是否已经存在此用户名，如果不存在进行注册录入数据
if (application.getAttribute(name) == null) {
//保存用户信息
String userInfo = name + "#" + pwd + "#" + new Date();
//将用户信息保存在服务器
application.setAttribute(name, userInfo);
//并且设置当前登陆会话
session.setAttribute("name", name);
%>
注册成功
<br /> 注册名:<%=name%><br /> 时间:<%=new Date()%><br /> 5秒后跳转至留言界面
<%
response.setHeader("refresh", "5;URL=message.jsp");
%>
<%
} else {//如果用户名已经存在则跳转
out.print("注册失败,用户名重复");
%>
<br />5秒后跳转至登陆界面
<%
response.setHeader("refresh", "5;URL=index.jsp");
%>
<%
}
%>
</body>
</html>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ page import="java.util.*"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>留言界面</title>
</head>
<body>
<form method="post" onsubmit="return checkFlag()">
<textarea cols="20" rows="5" name="mes">
这里请添加留言
</textarea>
<br /> <input type="submit" />
</form>
<br /> 实时留言信息
<br />
<%
String mes = request.getParameter("mes");
Object name = session.getAttribute("name");
List<String> list = new ArrayList<>();
//session判断用户名为空时，跳转至错误页面
if (name == null) {
%>
<jsp:forward page="error.jsp" />
<%
}
//首先判断留言信息是否为空，防止没有留言时报空指针异常
if (application.getAttribute("mes") != null) {
list = (List<String>) application.getAttribute("mes");
if (mes == null) {
for (String str : list) {
out.print(str + "<br/>");
}
} else if (mes != null) {
response.sendRedirect("message.jsp");//这里加入一个页面重定向，防止页面刷新时重新提交表单
list.add(0, name + ":" + new String(mes.getBytes("iso-8859-1"), "utf-8") + " 时间:" + new Date());
application.setAttribute("mes", list);
for (String str : list) {
out.print(str + "<br/>");
}
}
} else if (mes != null) {//否则，判断留言是否为空，直接将当前留言存入客户端，直接输出
response.sendRedirect("message.jsp");
list.add(0, name + ":" + new String(mes.getBytes("iso-8859-1"), "utf-8") + " 时间:" + new Date());
application.setAttribute("mes", list);
for (String str : list) {
out.print(str + "<br/>");
}
}
%>
</body>
<script>
<!--此脚本对页面刷新取消提交，自测无效，应该是浏览器自己的设置-->
var flag = false;
function checkFlag() {
if (flag == true) {
return false;
}
flag = true;
return true;
}
</script>
</html>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>错误界面</title>
</head>
<body>
非法接入
<br /> 5秒后跳转至登陆页面
<%
response.setHeader("refresh", "5;URL=index.jsp");
%>
</body>
</html>
