Java小项目之Login界面理解MVC(MySQL数据库基本操作)

　　说真的，第一次看到MVC时候的感觉就和看到面向对象编程一样，感觉很方。之后慢慢的写了一些代码，在理解面向对象编程的同时也看到了MVC，虽然现在还是用不到，但是我觉得还是有些了解的好。

　　先谈谈MVC：模型(model)：程序员编写程序应有的功能（实现算法等等）、数据库专家进行数据管理和数据库设计(可以实现具体的功能)。

　　　　　　　　 视图(view)：设计界面。

　　　　　　　　 控制(Controller)：处理事务。

　　很多地方可能我理解的不是很到位。只是能写出来一个大概，后续我还会更新。又重新查了一遍资料，感觉又开始有一种模糊的感觉，不理解什么是MVC了。先写，之后再修改。

一共写了四个包，dao(用来处理数据库操作的各项)，model(创建了一个模型user)，util(工具包，连接数据库和关闭连接)，view(界面设计)。

　　我们先新建一个数据库：db_login，然后在数据库下添加一个表，叫做user。

就是这么一个样子。

　　然后我们去设计一下model下的user类：和数据库中的一一对应，id(int)，userName(String)，password(String)。

package com.rookie.model;

public class User {
    private int id;
    private String userName;
    private String password;
    
    public User() {
        super();
        // TODO Auto-generated constructor stub
    }
    
    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;
    }
    
}

　　model类写好之后我们就去写util包下的DbUtil类。我用的是MySQL数据库，所以先去官网下载了Jar包，build-path导入包。然后开始写util中的控制包。

　　和正常的数据库连接一样。

package com.rookie.util;

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

public class DbUtil {
    
    String dbUrl = "jdbc:mysql://localhost:3306/db_login";
    String dbUser = "root";
    String dbPass = "salin";
    String driveName = "com.mysql.jdbc.Driver";
    
    public Connection getCon()throws Exception {
        Class.forName(driveName);
        Connection con = DriverManager.getConnection(dbUrl,dbUser,dbPass);
        return con;
    }
    
    public void closeCon(Connection con) {
        if(con!=null) {
            try {
                con.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

　　这里只写了创建连接和关闭连接，我把剩下的数据库增删改放在了Dao包下(很多地方说Dao包相当于MVC中的model)。

　　接下来的话我打算去设计View类，View分成了两部分，一部分是登陆界面，一部分是注册界面(小小的加深一下)。

　　整体界面就是这样，那些图标是在：http://www.easyicon.net 找的。值得一说的是注册账户哪里是一个标签，然后加入了鼠标点击监听(mouseClickedAction)，点击之后就会弹出一个注册界面：

　　没有很高大上的样子，就是为了能够多理解一下MVC。这个界面的设计还是使用了 WindowsBuilder 插件。很方便，而且也加入了自己的一些想法，比如鼠标进入编辑框后会把编辑框的边框变色，还有一些东西是在开发的时候才能找到。下面直接贴代码：

package com.rookie.view;

import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.border.LineBorder;

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

import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JTextField;
import javax.swing.JPasswordField;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.sql.Connection;
import java.awt.event.ActionEvent;
import javax.swing.SwingConstants;
import java.awt.Font;
import java.awt.Toolkit;
import java.awt.Color;


import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.ImageIcon;

public class UserLogin extends JFrame {
    /**
     * 用户登陆界面。
     */
    private static final long serialVersionUID = 1L;
    private JPanel contentPane;
    private JPasswordField text_password;
    private JButton bt_login;
    private JLabel l_Prompt;
    private Connection con;
    private DbUtil dbUtil;
    private UserDao userDao;
    private JLabel label_2;
    private JTextField text_username;
    private final int WINDOWWIDTH = 386;
    private final int WINDOWHEIGH = 256;
    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    UserLogin frame = new UserLogin();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the frame.
     */
    public UserLogin() {
        setTitle("u6B22u8FCEu767Bu9646");
        setResizable(false);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        contentPane = new JPanel();
        contentPane.setLayout(null);
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(contentPane);
        
        JLabel label = new JLabel("u7528u6237u540DuFF1A");
        label.setIcon(new ImageIcon(UserLogin.class.getResource("/icon/user.png")));
        label.setFont(new Font("黑体", Font.PLAIN, 12));
        label.setBounds(60, 66, 68, 27);
        contentPane.add(label);
        
        JLabel label_1 = new JLabel("u5BC6  u7801uFF1A");
        label_1.setIcon(new ImageIcon(UserLogin.class.getResource("/icon/pass.png")));
        label_1.setFont(new Font("黑体", Font.PLAIN, 12));
        label_1.setBounds(60, 103, 68, 27);
        contentPane.add(label_1);
        
        text_password = new JPasswordField();
        text_password.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseExited(MouseEvent e) {
                mouseExitedAction(e);
            }
            @Override
            public void mouseEntered(MouseEvent e) {
                mouseEnteredAction(e);
            }
        });
        text_password.setBounds(138, 106, 124, 21);
        contentPane.add(text_password);
        
        bt_login = new JButton("u767Bu9646");
        bt_login.setIcon(new ImageIcon(UserLogin.class.getResource("/icon/Login.png")));
        bt_login.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                loginAction(e);
            }
        });
        bt_login.setBounds(138, 160, 91, 40);
        contentPane.add(bt_login);
        
        l_Prompt = new JLabel("");
        l_Prompt.setForeground(Color.RED);
        l_Prompt.setFont(new Font("黑体", Font.PLAIN, 13));
        l_Prompt.setHorizontalAlignment(SwingConstants.CENTER);
        l_Prompt.setBounds(10, 29, 360, 27);
        contentPane.add(l_Prompt);
        
        label_2 = new JLabel("u6CE8u518Cu8D26u6237");
        label_2.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                new RegistUser().setVisible(true);;
            }
            @Override
            public void mouseEntered(MouseEvent e) {
                new RegistUser();
            }
        });
        label_2.setForeground(Color.BLUE);
        label_2.setBounds(284, 66, 53, 27);
        contentPane.add(label_2);
        
        text_username = new JTextField();
        text_username.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseEntered(MouseEvent e) {
                mouseEnteredAction(e);
            }
            @Override
            public void mouseExited(MouseEvent e) {
                mouseExitedAction(e);
            }
        });
        text_username.setBounds(138, 69, 124, 21);
        contentPane.add(text_username);
        text_username.setBorder(new LineBorder(new Color(0,0,0),1,false));
        text_password.setBorder(new LineBorder(new Color(0,0,0),1,false));
        text_username.setColumns(10);
        
        int width = Toolkit.getDefaultToolkit().getScreenSize().width;
        int heigh = Toolkit.getDefaultToolkit().getScreenSize().height;
        int x = (width-WINDOWWIDTH)/2;
        int y = (heigh-WINDOWHEIGH)/2;
        this.setBounds(x, y, WINDOWWIDTH, WINDOWHEIGH);
    }
    //鼠标进入编辑框事件
    private void mouseExitedAction(MouseEvent e) {
        // TODO Auto-generated method stub
        JTextField text =  (JTextField)e.getSource();
        text.setBorder(new LineBorder(new Color(0,0,0),1,false));
    }
    //鼠标退出编辑框事件
    private void mouseEnteredAction(MouseEvent e) {
        // TODO Auto-generated method stub
        JTextField text =  (JTextField)e.getSource();
        text.setBorder(new LineBorder(new Color(0,0,255),1,false));
    }

    private void loginAction(ActionEvent e) {
        User user = new User();
        String userName = text_username.getText();
        char[] pass = text_password.getPassword();
        String password = String.valueOf(pass);
        if(userName == null || userName.equals("")) {
            l_Prompt.setText("用户名不能为空！");
            return ;
        }else if(password == null || password.equals("")){
            l_Prompt.setText("密码不能为空！");
            return ;
        }
        user.setUserName(userName);
        user.setPassword(password);
        try {
            dbUtil = new DbUtil();
            userDao = new UserDao();
            con = dbUtil.getCon();
            User loginUser = userDao.login(con, user);
            if( loginUser != null ) {
                l_Prompt.setText("登陆成功，欢迎使用！");
            }else {
                l_Prompt.setText("用户名或密码错误！");
            }
        } catch (Exception e1) {
            dbUtil.closeCon(con);
        } finally {
            dbUtil.closeCon(con);
        }    
    }
}

package com.rookie.view;


import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JPasswordField;

import com.rookie.dao.RegisDao;
import com.rookie.dao.UserDao;
import com.rookie.model.User;
import com.rookie.util.DbUtil;

import javax.swing.JLabel;
import javax.swing.JTextField;
import java.awt.event.ActionListener;
import java.sql.Connection;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import javax.swing.SwingConstants;
import java.awt.Color;
import javax.swing.ImageIcon;

public class RegistUser extends JDialog {
    private Connection con;
    private DbUtil dbUtil;
    private RegisDao regisDao;
    private JTextField text_userName;
    private JPasswordField text_password;
    private JPasswordField text_repeat;
    private JLabel prompt;
    private final int WINDOWWIDTH = 296;
    private final int WINDOWHEIGH = 300;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        try {
            RegistUser dialog = new RegistUser();
            dialog.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
            dialog.setVisible(true);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * Create the dialog.
     */
    public RegistUser() {
        getContentPane().setForeground(Color.RED);
        setTitle("u7528u6237u6CE8u518C");
        setAlwaysOnTop(true);
        getContentPane().setLayout(null);
        
        JLabel label = new JLabel("*u7528u6237u540DuFF1A");
        label.setIcon(new ImageIcon(RegistUser.class.getResource("/icon/user.png")));
        label.setBounds(36, 42, 77, 18);
        getContentPane().add(label);
        
        JLabel label_1 = new JLabel("*u5BC6  u7801uFF1A");
        label_1.setIcon(new ImageIcon(RegistUser.class.getResource("/icon/pass.png")));
        label_1.setBounds(36, 80, 77, 15);
        getContentPane().add(label_1);
        
        text_userName = new JTextField();
        text_userName.setBounds(123, 42, 113, 21);
        getContentPane().add(text_userName);
        text_userName.setColumns(10);
        
        text_password = new JPasswordField();
        text_password.setEchoChar('*');
        text_password.setColumns(10);
        text_password.setBounds(123, 77, 113, 21);
        getContentPane().add(text_password);
        
        JLabel label_2 = new JLabel("*u91CDu590Du5BC6u7801uFF1A");
        label_2.setBounds(47, 122, 77, 15);
        getContentPane().add(label_2);
        
        text_repeat = new JPasswordField();
        text_repeat.setEchoChar('*');
        text_repeat.setColumns(10);
        text_repeat.setBounds(123, 119, 113, 21);
        getContentPane().add(text_repeat);
        
        JButton button = new JButton("");
        button.setIcon(new ImageIcon(RegistUser.class.getResource("/icon/Register.png")));
        button.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                addUserAction(e);
            }
        });
        button.setBounds(36, 185, 77, 33);
        getContentPane().add(button);
        
        JButton button_1 = new JButton("");
        button_1.setIcon(new ImageIcon(RegistUser.class.getResource("/icon/reset.png")));
        button_1.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                text_password.setText("");
                text_repeat.setText("");
                text_userName.setText("");
                prompt.setText("");
            }
        });
        button_1.setBounds(165, 185, 71, 33);
        getContentPane().add(button_1);
        
        prompt = new JLabel("");
        prompt.setForeground(Color.RED);
        prompt.setHorizontalAlignment(SwingConstants.CENTER);
        prompt.setBounds(36, 160, 200, 15);
        getContentPane().add(prompt);
        
        int width = Toolkit.getDefaultToolkit().getScreenSize().width;
        int heigh = Toolkit.getDefaultToolkit().getScreenSize().height;
        int x = (width-WINDOWWIDTH)/2;
        int y = (heigh-WINDOWHEIGH)/2;
        this.setBounds(x, y, 286, 278);
    }

    protected void addUserAction(ActionEvent e) {
        // TODO Auto-generated method stub
        String userName = text_userName.getText();
        char []pass = text_password.getPassword();
        String password = String.valueOf(pass);
        char []rep = text_repeat.getPassword();
        String repeat = String.valueOf(rep);
        if(userName.length() < 6) {
            prompt.setText("用户名长度错误！");
            return ;
        }else if( !password.equals(repeat) || (password.length() < 6 || password.length() > 20)){
            prompt.setText("密码存在问题！");
            return ;
        }
        User user = new User(userName, password);
        dbUtil = new DbUtil();
        regisDao = new RegisDao();
        try {
            con = dbUtil.getCon();
            boolean hasUser= regisDao.hasUser(con, user);
            if( hasUser == false) {
                regisDao.addUser(con, user);
                prompt.setText("添加成功!");
            }else {
                prompt.setText("用户名已存在!");
            }
        } catch (Exception e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        } finally {
            dbUtil.closeCon(con);
        }
    }

}

　　写完界面之后就是Dao类了，用来处理数据库事件，我也写了两个对应上面的View界面，一个是登陆，一个是注册。用了MySQL语句，并不是很难。

package com.rookie.view;


import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JPasswordField;

import com.rookie.dao.RegisDao;
import com.rookie.dao.LoginDao;
import com.rookie.model.User;
import com.rookie.util.DbUtil;

import javax.swing.JLabel;
import javax.swing.JTextField;
import java.awt.event.ActionListener;
import java.sql.Connection;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import javax.swing.SwingConstants;
import java.awt.Color;
import javax.swing.ImageIcon;

public class RegistUser extends JDialog {
    private Connection con;
    private DbUtil dbUtil;
    private RegisDao regisDao;
    private JTextField text_userName;
    private JPasswordField text_password;
    private JPasswordField text_repeat;
    private JLabel prompt;
    private final int WINDOWWIDTH = 296;
    private final int WINDOWHEIGH = 300;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        try {
            RegistUser dialog = new RegistUser();
            dialog.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
            dialog.setVisible(true);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * Create the dialog.
     */
    public RegistUser() {
        getContentPane().setForeground(Color.RED);
        setTitle("u7528u6237u6CE8u518C");
        setAlwaysOnTop(true);
        getContentPane().setLayout(null);
        
        JLabel label = new JLabel("*u7528u6237u540DuFF1A");
        label.setIcon(new ImageIcon(RegistUser.class.getResource("/icon/user.png")));
        label.setBounds(36, 42, 77, 18);
        getContentPane().add(label);
        
        JLabel label_1 = new JLabel("*u5BC6  u7801uFF1A");
        label_1.setIcon(new ImageIcon(RegistUser.class.getResource("/icon/pass.png")));
        label_1.setBounds(36, 80, 77, 15);
        getContentPane().add(label_1);
        
        text_userName = new JTextField();
        text_userName.setBounds(123, 42, 113, 21);
        getContentPane().add(text_userName);
        text_userName.setColumns(10);
        
        text_password = new JPasswordField();
        text_password.setEchoChar('*');
        text_password.setColumns(10);
        text_password.setBounds(123, 77, 113, 21);
        getContentPane().add(text_password);
        
        JLabel label_2 = new JLabel("*u91CDu590Du5BC6u7801uFF1A");
        label_2.setBounds(47, 122, 77, 15);
        getContentPane().add(label_2);
        
        text_repeat = new JPasswordField();
        text_repeat.setEchoChar('*');
        text_repeat.setColumns(10);
        text_repeat.setBounds(123, 119, 113, 21);
        getContentPane().add(text_repeat);
        
        JButton button = new JButton("");
        button.setIcon(new ImageIcon(RegistUser.class.getResource("/icon/Register.png")));
        button.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                addUserAction(e);
            }
        });
        button.setBounds(36, 185, 77, 33);
        getContentPane().add(button);
        
        JButton button_1 = new JButton("");
        button_1.setIcon(new ImageIcon(RegistUser.class.getResource("/icon/reset.png")));
        button_1.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                text_password.setText("");
                text_repeat.setText("");
                text_userName.setText("");
                prompt.setText("");
            }
        });
        button_1.setBounds(165, 185, 71, 33);
        getContentPane().add(button_1);
        
        prompt = new JLabel("");
        prompt.setForeground(Color.RED);
        prompt.setHorizontalAlignment(SwingConstants.CENTER);
        prompt.setBounds(36, 160, 200, 15);
        getContentPane().add(prompt);
        
        int width = Toolkit.getDefaultToolkit().getScreenSize().width;
        int heigh = Toolkit.getDefaultToolkit().getScreenSize().height;
        int x = (width-WINDOWWIDTH)/2;
        int y = (heigh-WINDOWHEIGH)/2;
        this.setBounds(x, y, 286, 278);
    }

    protected void addUserAction(ActionEvent e) {
        // TODO Auto-generated method stub
        String userName = text_userName.getText();
        char []pass = text_password.getPassword();
        String password = String.valueOf(pass);
        char []rep = text_repeat.getPassword();
        String repeat = String.valueOf(rep);
        if(userName.length() < 6) {
            prompt.setText("用户名长度错误！");
            return ;
        }else if( !password.equals(repeat) || (password.length() < 6 || password.length() > 20)){
            prompt.setText("密码存在问题！");
            return ;
        }
        User user = new User(userName, password);
        dbUtil = new DbUtil();
        regisDao = new RegisDao();
        try {
            con = dbUtil.getCon();
            boolean hasUser= regisDao.hasUser(con, user);
            if( hasUser == false) {
                regisDao.addUser(con, user);
                prompt.setText("添加成功!");
            }else {
                prompt.setText("用户名已存在!");
            }
        } catch (Exception e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        } finally {
            dbUtil.closeCon(con);
        }
    }

}

package com.rookie.dao;

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

import com.rookie.model.User;

public class RegisDao {
    
    public RegisDao() {
        super();
        // TODO Auto-generated constructor stub
    }
    
    public boolean hasUser(Connection con,User user) throws SQLException {
        String sql = "select * from user where userName=?";
        PreparedStatement pra = con.prepareStatement(sql);
        pra.setString(1, user.getUserName());
        ResultSet result = pra.executeQuery();
        if(result.next()) {
            String userName = result.getString("userName");
            if(userName.equals(user.getUserName())) {
                return true;
            }else {
                return false;
            }
        }else {
            return false;
        }
    }
    
    //添加用户
    public int addUser(Connection con,User user) throws SQLException {
        String sql = "insert into user(userName,password) values(?,?)";
        PreparedStatement pra = con.prepareStatement(sql);
        pra.setString(1, user.getUserName());
        pra.setString(2, user.getPassword());
        int resultNum = pra.executeUpdate();
        pra.close();
        return resultNum;
    }
    
    
    
}

　　学艺不精，还望多多指教。目前看来，MVC是将整个软件开发过程分成了三个部分而不是三个包，Model很多地方写着是数据库的处理，我是用Dao来代替，而把model写成了模型。

　　(图片来自网络)一种映射机制，并没有强制去规定哪个地方去写什么，就我目前而言，我更喜欢去在model封装数据库所对应的类。而控制层和view层是紧密联系的，甚至很多代码是无法独立出来的。

　　　　　　　　新手上路，请多包涵。

　　代码已经打包上传：链接：http://pan.baidu.com/s/1geDNPWR 密码：b6e0