<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>$Title$</title>
  </head>

  <script type="text/javascript">
    function changeActionToRegister(){
      var s = document.getElementById("idForm")
      s.setAttribute("action", "doRegister.jsp");
    }
    function changeActionToLogin(){
      var s = document.getElementById("idForm")
      s.setAttribute("action", "doLogin.jsp");
    }
  </script>

  <body>

  <form id="idForm" method="post">
    用户名:<input type="text" name="username"/>
    <br>
    密码:<input type="password"  name="password"/>
    <br>
  <input type="submit" onclick="changeActionToLogin()" value="登录">
  <input type="submit" onclick="changeActionToRegister()" value="注册">
  </form>

  </body>
</html>

doLogin.jsp

<%@ page import="com.bean.lty.UserBean" %>
<%@ page import="com.dao.lty.Dao" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <%
        UserBean userBean = new UserBean();
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        userBean.setUname(username);
        userBean.setUpassword(password);
        Dao dao = new Dao();
        int i = dao.UserLogin(userBean);
        if(i > 0){
            HttpSession session1 = request.getSession();
            session1.setAttribute("username",username);
            session1.setAttribute("password",password);
            request.getRequestDispatcher("success.jsp").forward(request,response);
        }else{
            response.sendRedirect("fail.jsp");
        }

    %>
</body>
</html>

doRegister.jsp

<%@ page import="com.bean.lty.UserBean" %>
<%@ page import="com.dao.lty.Dao" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>

<%
    UserBean userBean = new UserBean();
    String username = request.getParameter("username");
    String password = request.getParameter("password");
    userBean.setUname(username);
    userBean.setUpassword(password);
    Dao dao = new Dao();
    int i = dao.UesrRegister(userBean);
    if(i > 0){
        HttpSession session1 = request.getSession();
        session1.setAttribute("username",username);
        session1.setAttribute("password",password);
        request.getRequestDispatcher("ok.jsp").forward(request,response);
    }else{
        response.sendRedirect("error.jsp");
    }

%>

</body>
</html>
package com.bean.lty;

public class UserBean {

    private String uname;
    private String upassword;

    public UserBean() {

    }

    public UserBean(String uname, String upassword) {
        this.uname = uname;
        this.upassword = upassword;
    }

    public String getUname() {
        return uname;
    }

    public void setUname(String uname) {
        this.uname = uname;
    }

    public String getUpassword() {
        return upassword;
    }

    public void setUpassword(String upassword) {
        this.upassword = upassword;
    }
}
package com.dao.lty;

import com.bean.lty.UserBean;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

public class Dao {

    UserBean userBean = new UserBean();

    // 获取连接
    protected static Connection getConnection() throws Exception {
        Class.forName("com.mysql.jdbc.Driver");
        // 建立连接
        Connection conn = DriverManager.getConnection(
                "jdbc:mysql://localhost:3306/user_info?useUnicode=true&characterEncoding=utf8", "root", "root");

        return conn;
    }

    // 关闭连接
    public static void closeAll(Connection conn, PreparedStatement ps, ResultSet rs) throws Exception {
        if (rs != null)
            rs.close();
        if (ps != null)
            ps.close();
        if (conn != null)
            conn.close();
    }


    public int UesrRegister(UserBean userBean) throws Exception {
            int i = 0;
            Connection conn = getConnection();
            String sql = "insert into user(uname,upassword) values(?,?)";
            PreparedStatement ps = conn.prepareStatement(sql);
            ps.setString(1, userBean.getUname());
            ps.setString(2, userBean.getUpassword());
            return i = ps.executeUpdate();
    }


    public int UserLogin(UserBean userBean) throws Exception {
        int flag = 0;
        Connection conn = getConnection();
        String sql = "select * from user where uname = ? and upassword = ?";
        PreparedStatement ps = conn.prepareStatement(sql);
        ps.setString(1, userBean.getUname());
        ps.setString(2, userBean.getUpassword());
        ResultSet rs = ps.executeQuery();

        while (rs.next() == true){
            flag = 1;
        }

        return flag;
    }
}
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
您已成功注册！注册信息:用户名：<%=request.getSession().getAttribute("username")%>
密码：<%=request.getSession().getAttribute("password")%>
</body>
</html>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
注册信息不正确，请重新进行注册！！！
</body>
</html>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
登录成功！欢迎您,用户名：<%=request.getSession().getAttribute("username")%>
密码：<%=request.getSession().getAttribute("password")%>
</body>
</html>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
登录失败,用户名不存在！
</body>
</html>