关于MVC模式的登录注册

最近初学jsp，顺便编写了一个基于MVC开发模式的登录注册

1、util包用于连接数据库操作

package com.util;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class DbUtil {
    
    private String url="jdbc:mysql://localhost:3306/test";
    private String user="root";
    private String password="root";
    private String driver="com.mysql.jdbc.Driver";
    
    public Connection getCon() throws Exception{
        Class.forName(driver);
        Connection con=DriverManager.getConnection(url, user, password);
        return con;
    }
    
    public static void getClose(Connection con) throws SQLException{
        if(con!=null){
            con.close();
        }
    }
    
    /*public static void main(String[] args) {
        DbUtil db=new DbUtil();
        try {
            db.getCon();
            System.out.println("测试连接数据库，连接成功");
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            System.out.println("测试连接数据库，连接失败");
        }
        
    }*/
}

2、model层对于成员变量的get set方法控制

package com.model;

import java.sql.DriverManager;

import com.mysql.jdbc.Connection;
import com.mysql.jdbc.PreparedStatement;

public class User {

    private int id;
    private String username;
    private String password;
    
    
    public User() {
        super();
    }
    public User(String username, String password) {
        super();
        this.username = username;
        this.password = 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;
    }
    

}

3.dao层用于操作数据库的增删改查方法

package com.dao;

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


import com.ningmeng.model.User;

public class UserDao {
    
    public User login(Connection con,User user) throws SQLException{
        User resultUser=null;
        String sql="select * from user where name=? and password=?";
        PreparedStatement ps=con.prepareStatement(sql);//
        ps.setString(1, user.getUsername());
        ps.setString(2, user.getPassword());
        ResultSet rs=ps.executeQuery();
        if(rs.next()){
            resultUser=new User();
            resultUser.setUsername(rs.getString("name"));
            resultUser.setPassword(rs.getString("password"));
        }
        return resultUser;
    }
    public boolean insert(Connection con,User user)
    {
        String sql = "INSERT INTO user(name,password) VALUES (?,?)";  //添加的SQL语句
         boolean flag=false;  
         try{  
             PreparedStatement psta=con.prepareStatement(sql);// 
             psta.setString(1, user.getUsername());  
             psta.setString(2, user.getPassword());  
             flag=psta.executeUpdate()>0;
         }catch(Exception e){  
             e.printStackTrace();  
         }
             try {
                con.close();
            } catch (SQLException e) {
                
                e.printStackTrace();
            }
             return flag;      
    }
    
    //通过id查找  
    public User selectById(Connection con,int id){  
         
        PreparedStatement psta=null;  
        ResultSet rs=null;  
        User user=null;  
        String sql="select * from user where id=?";  
        try{  
            psta=con.prepareStatement(sql);  
            psta.setInt(1, id);  
            rs=psta.executeQuery();  
            if(rs.next()){  
                user=new User();  
                user.setId(rs.getInt(1));  
                user.setUsername(rs.getString(2));  
                user.setPassword(rs.getString(3));  

            }  
        }catch(Exception e){  
            e.printStackTrace();  
        } 
            try{  
                con.close();  
            }catch(Exception e){  
                e.printStackTrace();  
            }  
            return user;    
    }
  //更新方法（修改数据）（改）  
    public boolean update(Connection con,User user){  
        PreparedStatement psta=null;  
        String sql="update user set name=?,password=? where id=?";  
        boolean flag=false;  
        try{  
            psta=con.prepareStatement(sql);  
            psta.setString(1, user.getUsername());  
            psta.setString(2, user.getPassword());   
            psta.setInt(3,user.getId());  
            flag=psta.executeUpdate()>0;  
        }catch(Exception e){  
            e.printStackTrace();  
        }
            try{  
                con.close();  
            }catch(Exception e){  
                e.printStackTrace();  
            }  
            return flag;  
    } 
    
    public boolean deleteAdmin(Connection con,int id){  //删除
        String sql = "delete from user where id = ?";  //删除的SQL语句，根据ID删除
        try {
            PreparedStatement pst = con.prepareStatement(sql);
            pst.setInt(1, id);
            int count = pst.executeUpdate();
            pst.close();
            return count>0?true:false;  //是否删除的判断
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return false;
    }
    
}

4、Servlet控制连接前台界面

package com.web;

import java.io.IOException;
import java.sql.Connection;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import com.ningmeng.dao.UserDao;
import com.ningmeng.model.User;
import com.ningmeng.util.DbUtil;

public class LoginServlet extends HttpServlet{

    DbUtil db=new DbUtil();
    UserDao userDao=new UserDao();
    /**
     * 
     */
    private static final long serialVersionUID = 1L;

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

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username=request.getParameter("username");
        String password=request.getParameter("password");
        Connection con=null;
        try {
            User user=new User(username,password);
            con=db.getCon();
            User currentUser=userDao.login(con, user);
            if(currentUser==null){
                //System.out.println("no");
                request.setAttribute("error", "用户名或者密码错误");
                request.setAttribute("username", username);
                request.setAttribute("password", password);
                request.getRequestDispatcher("login.jsp").forward(request, response);
            }else{
                //System.out.println("yes");
                HttpSession session=request.getSession();
                session.setAttribute("currentUser",currentUser);
                response.sendRedirect("main.jsp");
            }
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
    }
    
    
}

package com.web;

import java.io.IOException;
import java.sql.Connection;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.ningmeng.dao.UserDao;
import com.ningmeng.model.User;
import com.ningmeng.util.DbUtil;

/**
 * Servlet implementation class RegistServlet
 */
@WebServlet("/RegistServlet")
public class RegistServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    DbUtil db=new DbUtil();
    UserDao userDao=new UserDao();
    /**
     * @see HttpServlet#HttpServlet()
     */
    public RegistServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username=request.getParameter("username");
        String password=request.getParameter("password");
        Connection con=null;
        
        User user=new User(username,password);
        try {
            con=db.getCon();
        } catch (Exception e) {
            
            e.printStackTrace();
        }
        boolean current=userDao.insert(con, user);
        System.out.print(current);
        System.out.print(user.getUsername());
        if(current){
             request.setAttribute("error", "注册成功");
            
        }else{
             request.setAttribute("error", "注册失败");
             request.getRequestDispatcher("Regist.jsp").forward(request, response);
        }
        
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

5、修改web.xml对应的servlet

6、前台页面展示

<%@ page language="java" contentType="text/html; charset=gbk"
    pageEncoding="gbk"%>
<!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=gbk">
<title>Insert title here</title>
</head>
<body>
<form action="login" method="post">
     <table>
         <tr>
             <th colspan="2">登录界面</th>
         </tr>
         <tr>
             <td>账号</td>
             <td><input type="text" id="username" name="username" value="${username}"></td>
         </tr>
         <tr>
             <td>密码：</td>
             <td><input type="text" id="password" name="password" value="${password}"></td>
         </tr>
         <tr>
             <td><input type="submit" value="提交"></td>
             <td><font color="red">${error}</font></td>
         </tr>
     </table>
 </form>
 </body>
</html>

<%@ page language="java" contentType="text/html; charset=gbk"
    pageEncoding="gbk"%>
<!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=gbk">
<title>Insert title here</title>
</head>
<body>
<form action="login" method="post">
     <table>
         <tr>
             <th colspan="2">注册界面</th>
         </tr>
         <tr>
             <td>账号</td>
             <td><input type="text" id="username" name="username" ></td>
         </tr>
         <tr>
             <td>密码：</td>
             <td><input type="text" id="password" name="password" ></td>
         </tr>
         <tr>
             <td><input type="submit" value="提交"></td>
             <td><font color="red">${error}</font></td>
         </tr>
     </table>
 </form>
 </body>
</html>

<%@ page language="java" contentType="text/html; charset=gbk"
    pageEncoding="gbk"%>
<!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=gbk">
<title>Insert title here</title>
</head>
<body>
 <p>登录成功</p>
 当前用户：${currentUser.username}<br/>
 当前密码：${currentUser.password}<br/>
 </body>
</html>