login.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>登录页面</title>
</head>
<body>
<h2>登录</h2>
<br>
<form action="login-action.jsp" method="post">
用户名<input name="username">(只能由字母组成,3~12位)<br> 密码<input
type="password" name="password">(6~12位)<br> <input
type="checkbox" name="keep"> 两周免登陆<br> <input
type="submit" value="登录">
</form>
<hr>
<%
//根据传回来的值显示错误信息
String index = request.getParameter("index");
if (index != null) {
if (index.equals("1")) {
out.print("<h1>用户名或密码为空</h1>");
} else if (index.equals("2")) {
out.print("<h1>用户名或密码不符合规则</h1>");
} else {
out.print("<h1>用户名或密码错误</h1>");
}
}
%>
</body>
</html>
login-action.jsp
<%@ page language="java" import="java.util.*,java.sql.*"
pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>逻辑判断</title>
</head>
<body>
<%
//接受用户名密码
String username = request.getParameter("username");
String password = request.getParameter("password");
if (!username.equals("") || !password.equals("")) {//如果用户名密码不为空
if (username.matches("[a-zA-Z]{3,12}")
&& password.matches("[a-zA-Z0-9]{6,12}")) {//如果符合规则
try {
//连接数据库,访问数据,查询用户名密码是否正确
//1.加载驱动
Class.forName("com.mysql.jdbc.Driver");
//2.获得数据库连接---创建路
String url = "jdbc:mysql://localhost:3306/mybase";
Connection con = DriverManager.getConnection(url,
"root", "root");
//3.获得语句执行平台,通过数据库连接对象获取到SQL语句的执行者对象---创建人
Statement stat = con.createStatement();
//4.调用执行者对象,执行sql语句获取结果集---创建桶
String sql = "select * from users where username='"
+ username + "' and password='" + password
+ "'";
ResultSet rs = stat.executeQuery(sql);
if (rs.next()) {//判断用户名密码是否正确
if (request.getParameter("keep") != null) {//如果勾选复选框则创建Cookie,令用户两周内不在登录
//Cookie
Cookie name = new Cookie("cname", username);
Cookie passwd = new Cookie("cpasswd", password);
name.setMaxAge(60 * 60 * 24 * 7 * 2);
passwd.setMaxAge(60 * 60 * 24 * 7 * 2);
response.addCookie(name);
response.addCookie(passwd);
}
//为了保证安全性,以session方式传递这两个值
session.setAttribute("sname", username);
session.setAttribute("spasswd", password);
//跳转到欢迎页面
response.sendRedirect("index.jsp");
} else {
//错误跳转,用户名密码有一项不正确就跳转到登录页面,并返回错误信息
response.sendRedirect("login.jsp?index=3");
}
} catch (Exception e) {
out.print(e.toString());
}
} else {
//错误跳转,用户名密码有一项不符合业务逻辑就跳转到登录页面,并返回错误信息
response.sendRedirect("login.jsp?index=2");
}
} else {
//错误跳转,用户名密码有一项为空就跳转到登录页面,并返回错误信息
response.sendRedirect("login.jsp?index=1");
}
%>
<br>
</body>
</html>
index.jsp
<%@ page language="java" import="java.util.*,java.sql.*,com.entity.User"
pageEncoding="UTF-8"%>
<!-- 需导入sql包,user实体包 -->
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>欢迎页面</title>
</head>
<body>
<h2>欢迎页面</h2>
<br>
<%
//获取session中信息
String username = (String) session.getAttribute("sname");
String password = (String) session.getAttribute("spasswd");
if (username == null) {//判断直接访问欢迎页面的用户是否合法
String cookiename = "";
String cookiepasswd = "";
Cookie[] cookies = null;
cookies = request.getCookies();
if (cookies.length > 1) {
cookiename = getCookieByName(cookies, "cname").getValue();
cookiepasswd = getCookieByName(cookies, "cpasswd")
.getValue();
if (!cookiename.equals("") && !cookiepasswd.equals("")) {//获取用户名密码,并在action页面验证
response.sendRedirect("login-action.jsp?username="
+ cookiename + "&password=" + cookiepasswd);
return;
}
}
//跳转登录
response.sendRedirect("login.jsp");
}
//显示欢迎
out.print("<h1>Welcome!" + username + "!</h1>");
%>
<%!// 创建方法,用于查找指定名称的cookie
public static Cookie getCookieByName(Cookie[] cs, String name) {
if (cs == null || cs.length == 0) {
return null;
}
for (Cookie c : cs) {
if (name.equals(c.getName())) {
return c;
}
}
return null;
}%>
<%!//读取数据库,存到List<User> list中
public List<User> readUser() {
List<User> list = new ArrayList<User>();
Connection con = null;
ResultSet rs = null;
try {//连接数据库的操作
Class.forName("com.mysql.jdbc.Driver");
String url = "jdbc:mysql://localhost:3306/mybase";
con = DriverManager.getConnection(url, "root", "root");
Statement stat = con.createStatement();
String sql = "select * from users ";
rs = stat.executeQuery(sql);
while (rs.next()) {
int id = rs.getInt("id");
String myusername = rs.getString("username");
String mypassword = rs.getString("password");
User u = new User(id, myusername, mypassword);
list.add(u);
}
} catch (Exception e) {
e.toString();
}
try {//关闭连接
if (rs != null) {
rs.close();
}
if (con != null) {
con.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
return list;
}%><hr>
<!-- 创建表格 -->
<table border="1">
<tr>
<th>id</th>
<th>username</th>
<th>password</th>
</tr>
<%
List<User> list = readUser();
for (User u : list) {
%><tr>
<td><%=u.getId()%></td>
<td><%=u.getUname()%></td>
<td><%=u.getUpasswd()%></td>
</tr>
<%
}
%>
</table>
</body>
</html>
User.java
package com.entity;
//实体类
public class User {
private int id;
private String uname;
private String upasswd;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getUname() {
return uname;
}
public void setUname(String uname) {
this.uname = uname;
}
public String getUpasswd() {
return upasswd;
}
public void setUpasswd(String upasswd) {
this.upasswd = upasswd;
}
public User(int id, String uname, String upasswd) {
super();
this.id = id;
this.uname = uname;
this.upasswd = upasswd;
}
public User() {
super();
}
@Override
public String toString() {
return "user [id=" + id + ", uname=" + uname + ", upasswd=" + upasswd
+ "]";
}
}
效果
登录之后,如果正确则会展示表.
