loginsystem.java

以一个酒店的进销存系统为例

package com.csbook.restaurant;

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import javax.swing.UIManager;
import com.csbook.restaurant.utility.*;


/**
 * <p>Title: </p>
 * <p>Description: </p>
 * <p>Copyright: Copyright (c) 2003</p>
 * <p>Company: </p>
 * @author pengtao
 * @version 1.0
 */

public class LoginSystem extends JDialog {
  private int logincount=0;
  private JPanel centerPanel = new JPanel();
  private JLabel jLabel2 = new JLabel();
  private JLabel jLabel3 = new JLabel();
  private JPasswordField password = new JPasswordField();
  private JTextField username = new JTextField();
  private JPanel southPanel = new JPanel();
  private JButton login = new JButton();
  private GridLayout gridLayout1 = new GridLayout(2,2);
  private JPanel northjPanel = new JPanel();
  private JLabel jLabel4 = new JLabel();
  private CheckUser cUser=new CheckUser();
  FlowLayout flowLayout1 = new FlowLayout();

  public LoginSystem(Frame frame, String title, boolean modal) {
    super(frame, title, modal);
    try {
      jbInit();
      pack();
    }
    catch(Exception ex) {
      ex.printStackTrace();
    }
  }

  public LoginSystem() {
    this(null, "登陆系统", false);
  }

  //初始化用户界面
  private void jbInit() throws Exception {
    centerPanel.setLayout(gridLayout1);
    jLabel2.setText("用户名：");
    jLabel3.setText("密码：");
    login.setText("登陆系统");
    login.addActionListener(new ActionListener(this));
    jLabel4.setText("请输入用户名和密码");
    northjPanel.setLayout(flowLayout1);
    centerPanel.add(jLabel2, null);
    centerPanel.add(username, null);
    centerPanel.add(jLabel3, null);
    centerPanel.add(password, null);
    this.getContentPane().add(northjPanel, BorderLayout.NORTH);
    northjPanel.add(jLabel4, null);
    this.getContentPane().add(southPanel,  BorderLayout.SOUTH);
    southPanel.add(login, null);
    this.getContentPane().add(centerPanel,  BorderLayout.CENTER);
    this.setVisible(true);
  }

  public void login_actionPerformed(ActionEvent e) {
      //取得用户输入的用户名
      String operator=username.getText();
      //取得用户输入的密码
      char temp[]=password.getPassword();
      String tempPass=new String(temp);
      //检查用户是否为合法用户
      if(cUser.isValidUser(operator,tempPass)==false){
        JOptionPane.showMessageDialog(this, "错误的用户名或密码", "错误",
                                      JOptionPane.WARNING_MESSAGE);
        logincount++;
        //如果输入错误三次，自动退出系统
        if(logincount>=3)
          System.exit(1);
      }
      else{
        //初始化系统主界面
        MainFrame frame=new MainFrame();
        //获取用户类型
        String userType=cUser.getUserType(operator);
        //将主界面置于屏幕中央
       Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
       Dimension frameSize = frame.getSize();
       if (frameSize.height > screenSize.height) {
          frameSize.height = screenSize.height;
       }
      if (frameSize.width > screenSize.width) {
         frameSize.width = screenSize.width;
       }
       int inset = 50;
      setBounds(inset, inset, screenSize.width - inset*2, screenSize.height-inset*2);
      frame.setLocation((screenSize.width - frameSize.width) / 2, (screenSize.height - frameSize.height) / 2);
      //将当前用户的名称传送给主界面
      frame.setOperator(operator);
      //设置用户可以使用的功能
      frame.setMenuStatus(userType);
      //显示主界面
      frame.setVisible(true);
      //关闭登陆窗口
      this.dispose();
      }
  }
}

class ActionListener implements java.awt.event.ActionListener {
  LoginSystem adaptee;

  ActionListener(LoginSystem adaptee) {
    this.adaptee = adaptee;
  }
  public void actionPerformed(ActionEvent e) {
    adaptee.login_actionPerformed(e);
  }
}