图书馆管理系统登陆界面

1、程序代码

package window;

import data.BaseDao;

import java.awt.AWTEvent;

import java.awt.Container;

import java.awt.Font;

import java.awt.GridLayout;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.awt.event.KeyAdapter;

import java.awt.event.KeyEvent;

import java.sql.ResultSet;

import javax.swing.*;

import javax.swing.plaf.FontUIResource;

import util.GlobalVar;

/**

* 类Login用于显示登录界面，要求系统用户输入正确的用户名和密码。*

* @author raymond

*/

public class Login extends JFrame {

private JLabel lb_user;

private JTextField tf_user;

private JLabel lb_pass;

private JPasswordField pf_pass;

private JButton btn_ok;

private JButton btn_cancel;

private int num = 0;//用来记录登陆不成功的次数

public Login() {

UIUtil.setUIFont(new FontUIResource("宋体", Font.BOLD, 15));

initComponents();

}

// 初始化组件

private void initComponents() {

lb_user = new JLabel();

tf_user = new JTextField();//用户名输入文本框

lb_pass = new JLabel();

pf_pass = new JPasswordField();//密码输入文本框

btn_ok = new JButton();//确认按钮

btn_cancel = new JButton();//取消按钮

setTitle("用户登录界面");

setResizable(false);

setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

Container contentPane = getContentPane();

contentPane.setLayout(new GridLayout(3, 2));

lb_user.setText("用户名：");

lb_user.setHorizontalAlignment(SwingConstants.RIGHT);

tf_user.addKeyListener(new KeyEnter());

contentPane.add(lb_user);

contentPane.add(tf_user);

lb_pass.setText("密码：");

lb_pass.setHorizontalAlignment(SwingConstants.RIGHT);

pf_pass.addKeyListener(new KeyEnter());

contentPane.add(lb_pass);

contentPane.add(pf_pass);

btn_ok.setText("确定");

btn_ok.addActionListener(new ActionListener() {

@Override

public void actionPerformed(ActionEvent e) {

btn_okActionPerformed(e);

}

});

contentPane.add(btn_ok);

btn_cancel.setText("取消");

btn_cancel.addActionListener(new ActionListener() {

@Override

public void actionPerformed(ActionEvent e) {

btn_cancelActionPerformed(e);

}

});

contentPane.add(btn_cancel);

setSize(225, 150);

setLocationRelativeTo(getOwner());

}

// "确定"按钮响应事件

private void btn_okActionPerformed(AWTEvent e) {

String user = tf_user.getText(); // 获得用户名

String pass = String.valueOf(pf_pass.getPassword()); // 获得密码

String username;

int is_admin;

// 未输入用户名

if (user.equals("")) {

JOptionPane.showMessageDialog(this, "用户名不允许为空！");

return;

}

try {

// 在数据库中查询

String sqlStr = "select * from users where name='" + user

+ "' and pass='" + pass + "'";

ResultSet result = BaseDao.executeQuery(sqlStr);

if (result.next()) {

username = result.getString("name");

is_admin = result.getInt("is_admin");

BaseDao.close();

} else {

JOptionPane.showMessageDialog(this, "用户名或密码不正确!");

BaseDao.close();

//当登录不成功次数超过3次，则自动退出

if (num < 3) {

num++;

} else {

JOptionPane.showMessageDialog(this, "尝试次数过多!");

this.dispose();

}

return;

}

GlobalVar.login_user = username; // 记录当前用户

// 进入主界面

Main main = new Main();

main.setPurView((byte) is_admin);

this.dispose();

} catch (Exception ex) {

System.out.println(ex.getMessage());

}