public class mail {
  
    private Integer id;
    private String Sender;
    private String addressee;
    private String title;
    private String content;
    private String time;
    private Integer state;
  
    public Integer getId() {
        return id;
    }
  
    public void setId(Integer id) {
        
 
this.id = id;
    }
  
    public String getSender() {
        return Sender;
    }
  
    public void setSender(String sender) {
        Sender = sender;
    }
  
    public String getAddressee() {
        return addressee;
    }
  
    public void setAddressee(String addressee) {
        this.addressee = addressee;
    }
  
    
 
public String getTitle() {
        return title;
    }
  
    public void setTitle(String title) {
        this.title = title;
    }
  
    public String getContent() {
        return content;
    }
  
    public void setContent(String content) {
        this.content = content;
    }
  
    public String getTime() {
        
 
return time;
    }
  
    public void setTime(String time) {
        this.time = time;
    }
  
    public Integer getState() {
        return state;
    }
  
    public void setState(Integer state) {
        this.state = state;
    }
  
    @Override
    public String toString() {
        return "mail{" +
                "id=" + id +
                ", Sender='" + Sender + '\'' +
                ", addressee='" + addressee + '\'' +
                ", title='" + title + '\'' +
                ", content='" + content + '\'' +
                ", time='" + time + '\'' +
                ", state=" + state +
                '}';
    }
}

public class MailUsers {
    private int id;
    private String username;
    private String password;
  
    public int getId() {
        return id;
    }
  
    public void setId(int id) {
        this.id = id;
    }
  
    public String getUsername() {
        return username;
    }
  
    public void setUsername(String username) {
        this.username = username;
    }
  
    public String getPassword() {
        return password;
    }
  
    public void setPassword(String password) {
        this.password = password;
    }
  
    @Override
    public String toString() {
        return "MailUsers{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
  
public class mail_UserDao extends mail_BaseDao{
    //--------------------使用者登入---------------------
    public boolean login(String name, String pwd) {
        boolean f = false;
        Connection conn = getConnection();
        String sql = "select * from tb_user where username=? and password=?";
        PreparedStatement ps = null;
        ResultSet rs = null;
        try {
            ps = conn.prepareStatement(sql);
            ps.setString(1, name);
            ps.setString(2, pwd);
            rs = ps.executeQuery();
            if (rs.next())
                f = true;
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            closeAll(conn, ps, rs);
        }
        return f;
    }
  
    //--------------------使用者註冊--------------------
    public void reg(String username, String password) {
        Connection conn = getConnection();
        PreparedStatement ps = null;
        try {
            String sql = "insert into tb_user(username,password) values(?,?)";
            ps = conn.prepareStatement(sql);
            ps.setString(1, username);
            ps.setString(2, password);
            ps.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            closeAll(conn, ps, null);
        }
  
    }
}
import com.own.mywebdemo.Week5_Login_connecor.BaseDao;
import org.jetbrains.annotations.NotNull;
  
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
  
public class MailDao extends mail_BaseDao {
    //--------------------查詢所有郵件--------------------
    public List<mail> getMailByReceiver(String name){
        List<mail> list=new ArrayList<mail>();
        Connection conn=getConnection();
        String sql="select * from tb_mail where addressee=?";
        PreparedStatement ps=null;
        ResultSet rs=null;
        try {
            ps = conn.prepareStatement(sql);
            ps.setString(1, name);
            rs=ps.executeQuery();
            while(rs.next()){
                mail m=new mail();
                m.setId(rs.getInt(1));
                m.setSender(rs.getString(2));
                m.setAddressee(rs.getString(3));
                m.setTitle(rs.getString(4));
                m.setContent(rs.getString(5));
                m.setTime(rs.getString(6));
                m.setState(rs.getInt(7));
                list.add(m);
            }
  
        } catch (SQLException e) {
            e.printStackTrace();
        }finally{
            closeAll(conn, ps, rs);
        }
        return list;
    }
  
    // --------------------插入郵件--------------------
    public void addMail(mail m) {
        Connection conn = getConnection();
        String sql = "insert into tb_mail(Sender,addressee,title,content,time,state) values(?,?,?,?,?,?)";
        PreparedStatement ps = null;
        try {
            ps = conn.prepareStatement(sql);
            ps.setString(1, m.getSender());
            ps.setString(2, m.getAddressee());
            ps.setString(3, m.getTitle());
            ps.setString(4, m.getContent());
            ps.setDate(5, new java.sql.Date(new Date().getTime()));// 系統當前時間
            ps.setInt(6, 0);
            ps.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            closeAll(conn, ps, null);
        }
    }
  
    // --------------------刪除郵件--------------------
    public void deleteMail(int id) {
        Connection conn = getConnection();
        String sql = "delete from tb_mail where id=?";
        PreparedStatement ps = null;
        try {
            ps = conn.prepareStatement(sql);
            ps.setInt(1, id);
            ps.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }finally{
            closeAll(conn, ps, null);
        }
  
    }
  
    //--------------------更新郵件狀態--------------------
    public void updataMail(int id){
        Connection conn = getConnection();
        String sql = "update tb_mail set state=1 where id=?";
        PreparedStatement ps = null;
        try {
            ps = conn.prepareStatement(sql);
            ps.setInt(1, id);
            ps.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }finally{
            closeAll(conn, ps, null);
        }
    }
  
}
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>登入</title>
</head>
<body>
<script type="text/javascript">
    function check() {
        if (login.account.value==""){
            alert("請輸入賬號!");
            return;
        }else if(login.psw.value=="") {
            alert("請輸入密碼!");
            return;
        }
        login.submit();
    }
</script>
<form action="checkLog.jsp" method="post" name="login">
    賬號:<input type="text" name="account"><br>
    密碼:<input type="password" name="psw"><br>
    <input type="button" value="登入" onclick="check()">
</form><br>
<form action="Register.jsp" method="post">
    <input type="submit" value="立即註冊賬戶">
</form>
</body>
</html>