Java如何实现简单登陆界面

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首先需要建立一个类，在这里，我命名为newLogin

newLogin类的代码如下

package p4;import java.awt.Dimension;import java.awt.Font;import java.awt.Toolkit;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.sql.Connection;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import javax.swing.ButtonGroup;import javax.swing.JButton;import javax.swing.JFrame;import javax.swing.JLabel;import javax.swing.JOptionPane;import javax.swing.JPassWordField;import javax.swing.JRadioButton;import javax.swing.JTextField;public class newLogin extends JFrame implements ActionListener{    private static final long serialVersionUID = 1L;    private Connection con = null;    private Statement statement = null;    private ResultSet res = null;    private ButtonGroup buttongroup = new ButtonGroup();    private MyPanel jp = new MyPanel();    private JLabel ul = new JLabel("用户名：");    private JLabel pl = new JLabel("密    码：");    private JLabel ts = new JLabel("");    private JTextField uname = new JTextField();    private JPasswordField pword = new JPasswordField();    private JRadioButton[] butArray = {            new JRadioButton("学生",true),            new JRadioButton("教师")    };    private JButton login = new JButton("登陆");    private JButton reset = new JButton("重置");    public newLogin() {        addListener();        initialFrame();    }    private void initialFrame() {        Font font = new Font("宋体",Font.BOLD,12);        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);        setTitle("登陆");        jp.setLayout(null);        ul.setBounds(100, 30, 60, 30);        jp.add(ul);        uname.setBounds(170, 30, 140, 30);        jp.add(uname);        pl.setBounds(100, 80, 60, 30);        pword.setBounds(170, 80, 140, 30);        jp.add(pl);        jp.add(pword);        ts.setBounds(100, 160, 200, 50);        jp.add(ts);        ts.setFont(font);        login.setBounds(100, 220, 70, 30);        jp.add(login);        login.setFont(font);        reset.setBounds(220, 220, 70, 30);        jp.add(reset);        reset.setFont(font);        add(jp);        setResizable(false);        buttongroup.add(butArray[0]);        buttongroup.add(butArray[1]);        butArray[0].setBounds(120, 130, 100, 50);        jp.add(butArray[0]);        butArray[1].setBounds(220, 130, 100, 50);        jp.add(butArray[1]);        butArray[0].setContentAreaFilled(false);        butArray[1].setContentAreaFilled(false);        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();        int centerX = screenSize.width/2;        int centerY = screenSize.height/2;        int w = 427;        int h = 331;        setBounds(centerX-w/2, centerY-h/2, w, h);        setVisible(true);        uname.requestFocus(true);        getContentPane().add(jp);        jp.getRootPane().setDefaultButton(login);    }    private void addListener() {        this.login.addActionListener(this);        this.uname.addActionListener(this);        this.pword.addActionListener(this);    }    @Override    public void actionPerfORMed(ActionEvent e) {        if(e.getSource() == uname) {            pword.requestFocus();        }        if(e.getSource() == pword) {            butArray[0].requestFocus();        }        if(e.getSource() == butArray[0]||e.getSource() == butArray[1]||e.getSource() == login) {//            this.ts.setText("正在为您努力加载，请稍等......");                        int type = this.butArray[0].isSelected()?0:1;            String username = this.uname.getText().trim();            char[] p = this.pword.getPassword();            String password = String.valueOf(p).trim();            if(username.equals("")) {                JOptionPane.showMessageDialog(this, "请输入用户名！","错误",JOptionPane.ERROR_MESSAGE);                ts.setText("");                return ;            }            if(password.equals("")) {                JOptionPane.showMessageDialog(this, "请输入密码！","错误",JOptionPane.ERROR_MESSAGE);                ts.setText("");                return ;            }            try {                con = new connection().getConnection();  //调用自己写的一个数据库连接类                statement = con.createStatement();                if(type == 0) {                    String sql = "select * from stuuser where "+                        "username_stu='"+username+"'and password_stu='"+password+"'";                    res = statement.executeQuery(sql);                    if(res.next()) {                        JOptionPane.showMessageDialog(this, "登录成功！","提示",JOptionPane.INFORMATION_MESSAGE);                        this.dispose();                    }                    else {                        JOptionPane.showMessageDialog(this, "用户名或密码错误！","错误",JOptionPane.ERROR_MESSAGE);                        ts.setText("");                        uname.setText("");                        pword.setText("");                    }                    //关闭数据库连接                    if(res != null) {                        res.close();                    }                    if(statement != null) {                        statement.close();                    }                    if(con != null) {                        con.close();                    }                }                else {                    String sql = "select * from teauser where "+                            "username_tea='"+username+"'and password_tea='"+password+"'";                        res = statement.executeQuery(sql);                        if(res.next()) {                            String spec_name = res.getString(1);                            JOptionPane.showMessageDialog(this, "登录成功！","提示",JOptionPane.INFORMATION_MESSAGE);                            this.dispose();                        }                        else {                            JOptionPane.showMessageDialog(this, "用户名或密码错误！","错误",JOptionPane.ERROR_MESSAGE);                            ts.setText("");                            uname.setText("");                            pword.setText("");                        }                        //关闭数据库连接                        if(res != null) {                            res.close();                        }                        if(statement != null) {                            statement.close();                        }                        if(con != null) {                            con.close();                        }                }            }catch(SQLException ea) {                ea.printStackTrace();            }        }        else if(e.getSource() == reset) {            uname.setText("");            pword.setText("");        }    }}

编写数据库连接类，在这里命名为connection,然后在类里写一个获取连接的放回，并返回一个连接。

connection类的代码如下：

package p4;import java.sql.Connection;import java.sql.DriverManager;//import java.sql.ResultSet;import java.sql.SQLException;//import java.sql.Statement;public class connection {    private Connection con = null;//    private Statement statement = null;//    private ResultSet res = null;    String driver = "com.mysql.cj.jdbc.Driver";    String url  = "jdbc:Mysql://localhost:3306/Stu_manager?serverTimezone=Asia/Shanghai";    String name = "root";    String passwd = "123456";    public connection() {            }    public Connection getConnection() {        try{            Class.forName(driver).newInstance();            con = DriverManager.getConnection(url,name,passwd);            }catch(ClassNotFoundException e){                System.out.println("对不起，找不到这个Driver");                e.printStackTrace();            }catch(SQLException e){                                e.printStackTrace();            }catch(Exception e){                e.printStackTrace();            }        return con;    }}

在mysql数据库中需建立两个用户表，分别用来存储不同用户的登陆账号和密码，这里学生用户表为stuuser,教师用户表为teauser,建表的SQL语句如下:

stuuser表：

create table stuuser(    username_stu varchar(20) primary key,    password_stu char(20) not null,)ENGINE=InnoDB DEFAULT CHARSET=utf8;

teauser表：

create table teauser(    username_tea varchar(20) primary key,    password_tea char(20) not null,)ENGINE=InnoDB DEFAULT CHARSET=utf8;

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