一.数据库db_01   表usert   字段username，password

二. 目录

三. 配置信息

四. 代码

 index.jsp

<script type="text/javascript">
  function refresh() {
  src="index.jsp?id="+Math.random();
  }
</script>
<%@ page contentType="charset=UTF-8" language="java"
         import ="java.awt.*"
         import ="java.awt.image.BufferedImage"
         import="java.util.*"
         import="javax.imageio.ImageIO"
         pageEncoding="gb2312"
%>

<%
  response.setHeader("Cache-Control","no-cache");
//在内存中创建图像
  int width=60,height=20;
  BufferedImage image=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
  //获取画笔
  Graphics g=image.getGraphics();
  //设置背景色
  g.setColor(new Color(200,200,200));
  g.fillRect(0,0,width,height);
  //取随机产生的验证码(4位数字)
  Random rnd=new Random();
  int randNum=rnd.nextInt(8999)+1000;
  String randStr=String.valueOf(randNum);
  //将验证码存入session
  session.setAttribute("randStr",randStr);
  //将验证码显示到图像中
  g.setColor(Color.black);
  g.setFont(new Font("", Font.PLAIN,20));
  g.drawString(randStr,10,17);
  //随机产生100个干扰点，使图像中的验证码不易被其他程序探测到
  for (int i = 0; i < 100; i++) {
    int x=rnd.nextInt(width);
    int y=rnd.nextInt(height);
    g.drawOval(x,y,1,1);
  }
  //输出图像到页面
  ImageIO.write(image,"JPEG",response.getOutputStream());
  out.clear();
  out=pageContext.pushBody();

%>

LoginServlet.jsp

<%@ page import="java.net.URLEncoder" %>
<%@ page contentType="text/html;charset=UTF-8" pageEncoding="utf-8" language="java" %>


    


<script type="text/javascript">
    function validate() {
        if(login.username1.value===""){
            alert("账号不能为空");
            return;
        }
        if(login.passwd.value===""){
            alert("密码不能为空");
            return;
        }
        if(login.code.value===""){
            alert("请输入正确的验证码");
            return;
        }
        login.submit();
    }
    function refresh() {
        login.imgValidate.src="index.jsp?id="+Math.random();
    }
</script>

"login" action="/LoginCl" method="post">
    用户名:"text" name="username1">

    密码："password" name="passwd">

    "checkbox" name="keep" >两周内免登陆

    验证码："text" name="code" size=10>
    <%--点击图片可进行验证码刷新--%>
    "imgValidate" src = "index.jsp" onclick="refresh()" >


    "button" value="登录"  onclick="validate()">
    <%
        String username = null;
        String password = null;
        Cookie[] cookies = request.getCookies();
        for (int i = 0; i < cookies.length; i++) {
            if ("username".equals(cookies[i].getName())) {
                username = cookies[i].getValue();
            } else if ("password".equals(cookies[i].getName())) {
                password = cookies[i].getValue();
            }
        }
        if (username != null && password != null) {
            response.sendRedirect("welcome.jsp?uname=" +URLEncoder.encode(username,"utf-8")+ "&password=" + password);
        }
    %>


"register.jsp" method="post">
    "submit" value="注册">

register.jsp

<%@ page language="java" pageEncoding="gb2312" %>


    


欢迎您进行注册
<script language="JavaScript" type="text/javascript">
    function checkPassword() {
        var ps=/^[A-Za-z0-9]{6,20}$/;
        if (!ps.exec(register.password1.value)) {
            alert("密码必须同时包含大小写字母和数字且长度应该在6-20之间");
            return;
        }
        register.submit();
    }
</script>
"register" action="registerMessage.jsp" method="post">
    请输入账号："text" name="name">

    请输入密码:
    "password" name="password1">(要求：必须包含大小写英文和数字无非法字符，长度大于6位小于20位)

    请选择性别："sex" type="radio" value="男" checked>男
    "sex" type="radio" value="女" >女

    请选择家乡：<select name="home" >
    "北京">北京
    "上海">上海
    "江西">江西
select>
    

    请选择您的爱好："fav" type="checkbox" value="唱歌">唱歌
    "fav" type="checkbox" value="跳舞">跳舞
    "fav" type="checkbox" value="打球">打球
    "fav" type="checkbox" value="玩游戏">玩游戏

    "button" value="注册" onclick="checkPassword()">

registerMessage.jsp

<%@ page import="java.sql.*" %>
<%@ page import="login.Dao.UserDao" %>
<%@ page language="java"  pageEncoding="gb2312" %>


    


信息注册成功!该用户注册信息如下：
<%
    request.setCharacterEncoding("gb2312");
    String name=request.getParameter("name");
    String  password=request.getParameter("password1");
    String sex = request.getParameter("sex");
    String home = request.getParameter("home");
    out.println("账号："+name);
    out.println("密码："+password);
    out.println("性别："+sex);
    out.println("家乡："+home);
    out.println("兴趣爱好：");
    String[] fav = request.getParameterValues("fav");
    for (int i = 0; i < fav.length; i++) {
        out.print(fav[i]+" ");
    }
    try {
        UserDao userDao=new UserDao();
        userDao.insertUser(name,password);
        out.println("
 信息注册成功，点击此处进行登录");
    } catch (SQLException e) {
        e.printStackTrace();
    }
%>

Bean层：

Counter.java

package login.Bean;

public class Counter {
    private int count=1;
    public Counter(){}
    public int getCount() {
        return count++;
    }

    public void setCount(int count) {
        this.count = count;
    }

}

user.java

package login.Bean;

public class User {
    private String name;
    private String pd;
    public User(){}
    public String getPd() {
        return pd;
    }
    public void setPd(String pd) {
        this.pd = pd;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
}

Dao层：

UserDao.java

package login.Dao;

import java.sql.*;
import java.util.ArrayList;

public class UserDao {
    public boolean SearchUser(String u,String p) throws SQLException {
        PreparedStatement preparedStatement = null;
        ResultSet rs =null;
        Connection con = null;
        //启动mysql驱动器
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            con = DriverManager.getConnection("jdbc:mysql://localhost:3306/db_01?useUnicode=true&characterEncoding=utf-8", "root", "root");
            String sql = "select * from usert where username=? and password=?";
            preparedStatement = con.prepareStatement(sql);
            preparedStatement.setString(1, u);
            preparedStatement.setString(2, p);
            rs = preparedStatement.executeQuery();
            if(rs.next()){
                return true;
            }
            else {
                return false;
            }

        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        finally {
            if(rs!=null) {
                rs.close();
            }
            if(preparedStatement!=null) {
                preparedStatement.close();
            }
            if(con!=null){
                System.out.println("数据库连接成功！");
                con.close();
            }
        }
        return false;
    }

    public void insertUser(String u,String p) throws SQLException {
        ArrayList users=new ArrayList();
        PreparedStatement preparedStatement = null;
        Connection con = null;
        //启动mysql驱动器
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            con = DriverManager.getConnection("jdbc:mysql://localhost:3306/db_01?useUnicode=true&characterEncoding=utf-8", "root", "root");
            preparedStatement = con.prepareStatement("insert into usert values(?,?)");
            preparedStatement.setString(1,u);
            preparedStatement.setString(2,p);
            preparedStatement.executeUpdate();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        finally {
            if(con!=null) {
                con.close();
            }
            if(preparedStatement!=null) {
                preparedStatement.close();
            }
        }
    }

}

Register层：

LoginCl.java (servlet)

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;
import java.net.URLEncoder;
import java.sql.SQLException;

@WebServlet(name = "LoginCl", value = "/LoginCl")
public class LoginCl extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //中文乱码解决方法
        response.setContentType("text/html;charset=utf-8");
        request.setCharacterEncoding("utf-8");
        //防止非法登录    得到session
        HttpSession httpSession = request.getSession(true);
        //修改session的存在时间为20s
        httpSession.setMaxInactiveInterval(20);
        httpSession.setAttribute("pass", "ok");
        //获取用户名的账号和密码
        String u = null;
        //针对jsp 其username为username1
        u = request.getParameter("username1");
        String p = null;
        p = request.getParameter("passwd");
        //得到提交的验证码
        String code = request.getParameter("code");
        //获取session验证码
        HttpSession session = request.getSession();
        String randStr = (String) session.getAttribute("randStr");
        //获取到
        if (code.equals(randStr)) {
            //访问数据库
            UserDao userDao=new UserDao();
            try {
                if (!userDao.SearchUser(u,p)) {
                    response.getWriter().println("抱歉：账号或密码错误，请注意核实信息重新输入");
                    return;
                } else {
                    String keep = request.getParameter("keep");
                    if (keep != null) {
                        //创建cookie
                        Cookie cookie1 = new Cookie("username", u);
                        Cookie cookie2 = new Cookie("password", p);
                        //设置关联路径
                        cookie1.setPath(request.getContextPath());
                        cookie2.setPath(request.getContextPath());
                        //设置cookie的消亡时间  两周
                        cookie1.setMaxAge(2 * 7 * 24 * 60 * 60);
                        cookie1.setMaxAge(2 * 7 * 24 * 60 * 60);
                        //把cookie信息写给浏览器
                        response.addCookie(cookie1);
                        response.addCookie(cookie2);
                    }
                    response.sendRedirect("welcome.jsp?uname=" + URLEncoder.encode(u, "utf-8") + "&password=" + p);
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request,response);
    }
}

web.xml

welcom.jsp

<%@ page import="java.util.Date" %>
<%@ page contentType="text/html;charset=gb2312" pageEncoding="gb2312" language="java" import="login.Bean.*"
%>
<%@ page import="java.net.URLDecoder" %>


    


<%
    request.setCharacterEncoding("gb2312");
    HttpSession httpSession=request.getSession(true);
    String val=(String)httpSession.getAttribute("pass");
    if(val==null){
        response.sendRedirect("LoginServlet.jsp");
    }
    int counter=0;
    application.setAttribute("COUNTER",new Integer(counter));
%>
"mycount" class="login.Bean.Counter" scope="session"/>
"user" class="login.Bean.User" scope="session">
    "user"  property="name" param="uname"/>
    "user" property="pd" param="password"/>

主界面
<%--welcome name =<%=u%>  password =<%=p%>
--%>
<%--welcome name :"user" property="name" />--%>
welcome name :
<%
    out.println(URLDecoder.decode(user.getName(),"utf-8"));
%>
password:"user" property="pd" />


<%--welcome name :<%out.println(session.getAttribute("username"));%>
password:<%out.println(session.getAttribute("password"));%>
--%>
<%--这是你第:<%=counter%>次访问本网站!
--%>
这是你第:"mycount" property="count"/>
次访问本网站!

'LoginServlet.jsp'>返回重新登录

<%
    Cookie[] cookies = request.getCookies();
    if(cookies!=null) {
        for (int i = 0; i < cookies.length; i++) {
            if (cookies[i].getName().equals("lastAccessTime")) {
                out.println("您上次访问的时间是：");
                Long lastAccessTime = Long.parseLong(cookies[i].getValue());
                Date date = new Date(lastAccessTime);
                out.println(date.toLocaleString());
            }
        }
    }



    //用户访问过后重新设置用户的访问时间，存储在cookie中，然后发送到客户端浏览器
    Cookie cookie=new Cookie("lastAccessTime",System.currentTimeMillis()+"");
    //设置cookie的有效期为5min
    cookie.setMaxAge(300);
    //将cookie对象添加到response对象中，这样服务器在输出response对象中的内容时
    // 就会把cookie也输入到客户端浏览器
    response.addCookie(cookie);
%>

 五. 效果

输入登录信息之后：

 数据库信息：