loginwindow.java

利用JCREATOR环境,实现用户登录窗口的编程的实例,为基本界面

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;
class   LoginWindow extends JDialog implements ActionListener
{    JPanel p1=new JPanel(); //定义并建立面板
     JPanel p2=new JPanel();
JPanel p3=new JPanel();
JPanel p4=new JPanel();
JPanel p5=new JPanel();
JTextField txtUserName=new JTextField(15); //用户名文本框
JPasswordField txtPwd=new JPasswordField(15);//密码框
JButton ok=new JButton("确定");
JButton cancel=new JButton("取消");
public LoginWindow(){
    setModal(true); //设置模态
    setBackground(Color.LIGHT_GRAY);//设置背景色
    Container contentPane=this.getContentPane();//取出内容面板
    contentPane.setLayout(new GridLayout(5,1)); //设置布局为5行1列
    p2.add(new JLabel("用户名:"));p2.add(txtUserName); //将组件添加到中间容器
    p3.add(new JLabel("密     码:"));p3.add(txtPwd);
    p4.add(ok);p4.add(cancel);
    ok.addActionListener(this);
    cancel.addActionListener(this);
    txtUserName.addActionListener(this);
    txtPwd.addActionListener(this);
    contentPane.add(p1);   //将面板添加到内容面板
       contentPane.add(p2);
    contentPane.add(p3);
    contentPane.add(p4);
    contentPane.add(p5);
    setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);//设置自动关闭窗口
    setSize(300,220);
    Dimension screen=Toolkit.getDefaultToolkit().getScreenSize();
    setLocation((screen.width-300)/2,(screen.height-220)/2);
    setTitle("登录窗口");
    setResizable(false); //不让用户改变窗口大小
    setVisible(true);
    }
public void actionPerformed(ActionEvent e){
    if(e.getSource()==ok||e.getSource()==txtPwd)   //单击确定按钮后
   { if(txtUserName.getText().trim().equals("123") && txtPwd.getText().trim().equals("123"))
    {dispose();   //关闭登录窗口
           //new MainWindow(); //调出主窗口
     }
            else
    { JOptionPane.showMessageDialog(null,"用户名或密码错误!");
         txtUserName.requestFocus(); //设置焦点
      txtUserName.setSelectionStart(0); //设置选中文本开始位置
      txtUserName.setSelectionEnd(txtUserName.getText().length());
       }
      }
       else if(e.getSource()==cancel) //单击取消
   {   dispose();
      System.exit(0);
      }
       else if(e.getSource()==txtUserName) //在用户名文本框按回车移动焦点到密码框
      { txtPwd.requestFocus();
   }
}
public static void main(String[] args) 
{
   JDialog.setDefaultLookAndFeelDecorated(true);
   Font font=new Font("JFrame",Font.PLAIN,14);
   Enumeration keys=UIManager.getLookAndFeelDefaults().keys();
   while(keys.hasMoreElements())
   { Object key=keys.nextElement();
     if(UIManager.get(key) instanceof Font)UIManager.put(key,font);
   }
   new LoginWindow();
}
}