login.java

里面所含源码是本人平时做程序的一些实例

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
public class  Login extends JFrame  implements ActionListener
{
	JPanel  pnlLogin;
 	JButton  btnLogin,btnRegister,btnExit;
	JLabel  lblServer,lblUserName,lblPassword,lblLogo;
	JTextField  txtUserName,txtServer;
	JPasswordField pwdPassword;
	RandomAccessFile rafUser;
	String str1[]=new String[2];
    String[] str2=saveToFile();
	String  strServerIp;
	
   //用于将窗口定位
	Dimension scrnsize;
	Toolkit toolkit=Toolkit.getDefaultToolkit();
	//构造方法 
	          	   
	public Login()
	{
		super("登录[HappyChat]聊天室");
		pnlLogin=new JPanel();
		this.getContentPane().add(pnlLogin);
		 
		lblServer=new JLabel("服务器(S):");
		lblUserName=new JLabel("用户名(U):");
		lblPassword=new JLabel("口  令(P):");
		txtServer=new JTextField(20);
		txtServer.setText("127.0.0.1");
		txtUserName=new JTextField(20);
		pwdPassword=new JPasswordField(20);
		btnLogin=new JButton("登录(L)");
		btnLogin.setToolTipText("登录到服务器");
		btnLogin.setMnemonic('L');
		btnRegister=new JButton("注册(R)");
		btnRegister.setToolTipText("注册新用户");
		btnRegister.setMnemonic('R');
		btnExit=new JButton("退出(X)");
		btnExit.setToolTipText("退出系统");
		btnExit.setMnemonic('X');
		
		pnlLogin.setLayout(null);  
		pnlLogin.setBackground(new Color(52,130,203));
		
		lblServer.setBounds(50,100,100,30);
		txtServer.setBounds(150,100,120,25);
		lblUserName    .setBounds(50,130,100,30);
		txtUserName    .setBounds(150,130,120,25);
		lblPassword    .setBounds(50,160,100,30);
		pwdPassword.setBounds(150,160,120,25);	
		btnLogin       .setBounds(50,200,80,25);
		btnRegister     .setBounds(130,200,80,25);
		btnExit        .setBounds(210,200,80,25);
		
		Font fontstr=new Font("宋体",Font.PLAIN,12);
		lblServer.setFont(fontstr);
		txtServer.setFont(fontstr);
		lblUserName    .setFont(fontstr);
		txtUserName    .setFont(fontstr);
		lblPassword    .setFont(fontstr);
		pwdPassword.setFont(fontstr);
		btnLogin.setFont(fontstr);
		btnRegister.setFont(fontstr);
		btnExit.setFont(fontstr);
		
		lblUserName.setForeground(Color.BLACK);
		lblPassword.setForeground(Color.BLACK);
		btnLogin.setBackground(Color.ORANGE);
		btnRegister.setBackground(Color.ORANGE);
		btnExit.setBackground(Color.ORANGE);
		
		pnlLogin.add(lblServer);
		pnlLogin.add(txtServer);
		pnlLogin.add(lblUserName);
		pnlLogin.add(txtUserName);
		pnlLogin.add(lblPassword);
		pnlLogin.add(pwdPassword);		
		pnlLogin.add(btnLogin);
		pnlLogin.add(btnRegister);
		pnlLogin.add(btnExit);
		
		//设置背景图片
		Icon logo1 = new ImageIcon("images\\loginlogo.jpg");
	 	lblLogo = new JLabel(logo1);
		lblLogo.setBounds(0,0,340,66);
		pnlLogin.add(lblLogo);
        //设置登录窗口
        setResizable(false);
		setSize(340,260);
		setVisible(true);
	    scrnsize=toolkit.getScreenSize();
    	setLocation(scrnsize.width/2-this.getWidth()/2,
    	                 scrnsize.height/2-this.getHeight()/2);
    	Image img=toolkit.getImage("images\\appico.jpg");
        setIconImage(img);
			
		//三个按钮注册监听
		btnLogin  .addActionListener(this);
		btnRegister.addActionListener(this);
		btnExit   .addActionListener(this);
		
	}  	
	
	public void actionPerformed(ActionEvent ae)
	{
	
		if (ae.getSource().equals(btnLogin))
		{
		    //判断用户名和密码是否为空
	    	if(txtUserName.getText().equals("") || pwdPassword.getText().equals(""))
		    {
			    JOptionPane op1=new JOptionPane();
                op1.showMessageDialog(null,"用户名或密码不能为空");
                return;
            }
            if(!txtUserName.getText().equals(str2[0]))
		    {
			    JOptionPane.showMessageDialog(null,"用户名不正确");
                return;
            }
            if(!pwdPassword.getText().equals(str2[1]))
              {	JOptionPane.showMessageDialog(null,"密码不正确");
                return;
              }
		    JOptionPane.showMessageDialog(null,"登录成功");
		}
		if (ae.getSource().equals(btnRegister))
		{
		    new Register();
		    this.dispose();
		    
		}
		if (ae.getSource() == btnExit)
		{
		    System.exit(0);
		}
	} 
    public String[] saveToFile()
	{
		try
		{
			//构造可读写RandomAccessFile对象
			rafUser=new RandomAccessFile("user.txt","rw");
			//文件指针定位到文件开始处
			rafUser.seek(0);					
		    str1[0]=rafUser.readLine();
		    str1[1]=rafUser.readLine();		
			rafUser.close();
			return str1;
		}
		catch(Exception e)
		{
			JOptionPane.showMessageDialog(null,"文件读取失败!");
		    return null;
		}
	}
	public static void main(String args[])
	{
		new Login();
	}
	
}