login.java

里面所含源码是本人平时做程序的一些实例

import java.awt.*;
import javax.swing.*;
import java.util.*;
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 ras;
	//用于窗口定位
	Dimension scrnsize;
	Toolkit tk=Toolkit.getDefaultToolkit();
	Conn c;
	//构造方法
	public Login(){
		super("登录聊天室");
		c=new Conn();
		pnlLogin=new JPanel();
		this.getContentPane().add(pnlLogin);
		//初始化组件
		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("");
		pwdPassword=new JPasswordField("");
		btnLogin=new JButton("登录(L)");
		btnLogin.addActionListener(this);
		btnLogin.setToolTipText("登录到服务器");
		btnLogin.setMnemonic('L');
		btnRegister=new JButton("注册(R)");
		btnRegister.addActionListener(this);
		btnRegister.setToolTipText("注册新用户");
		btnRegister.setMnemonic('R');
		btnExit=new JButton("退出(X)");
		btnExit.addActionListener(this);
		btnExit.setToolTipText("退出系统");
		btnExit.setMnemonic('X');
		//设置面板背景颜色
		pnlLogin.setBackground(new Color(52,130,203));
		//设置组件位置
		pnlLogin.setLayout(null);
		lblServer.setBounds(70,100,80,30);
		txtServer.setBounds(140,100,120,25);
		lblUserName.setBounds(70,130,80,30);
		txtUserName.setBounds(140,130,120,25);
		lblPassword.setBounds(70,160,80,30);
		pwdPassword.setBounds(140,160,120,25);
		btnLogin.setBounds(50,200,80,25);
		btnRegister.setBounds(130,200,80,25);
		btnExit.setBounds(210,200,80,25);
		//设置组件字体
		Font font=new Font("宋体",Font.PLAIN,12);
		btnLogin.setFont(font);
		btnRegister.setFont(font);
		btnExit.setFont(font);
		//设置组件背景颜色
		lblUserName.setForeground(Color.BLACK);
		lblPassword.setForeground(Color.BLACK);
		btnLogin.setBackground(Color.green);
		btnRegister.setBackground(Color.green);
		btnExit.setBackground(Color.green);
		//设置背景图片
		Icon logo=new ImageIcon("e:/java/images/loginlogo.jpg");
		lblLogo=new JLabel(logo);
		lblLogo.setBounds(0,0,340,60);
		//添加到组件面板
		pnlLogin.add(lblLogo);
		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);
		//设置登录窗口
		scrnsize=tk.getScreenSize();
		setLocation(scrnsize.width/2-this.getWidth()/2,scrnsize.height/2-this.getHeight()/2);
		Image img=tk.getImage("e:/java/images/login_qq.jpg");
		setIconImage(img);
		setResizable(false);
		setSize(340,260);
		setVisible(true);
		setDefaultCloseOperation(EXIT_ON_CLOSE);
	}
	//按钮监听响应
	public void actionPerformed(ActionEvent ae)
	{
		Object source=ae.getSource();
		JOptionPane op1=new JOptionPane();
		String strUser;
		
		if(source==btnLogin)
		{
			//判断用户名与密码是否为空
			if(txtUserName.getText().equals("") || pwdPassword.getPassword().length==0)
			{
				op1.showMessageDialog(null,"用户名或密码不能为空","提示",JOptionPane.INFORMATION_MESSAGE);
				return;
			}
		
				String sql="select * from users where U_Name='"+txtUserName.getText()+"'and U_pass='"+pwdPassword.getText()+"'";
				//调用Conn类下的方法进行用户名和密码校验
				if(c.executesql(sql))
				{
					new Chat();
					this.dispose();
				}
			//利用文件校验
			/*	boolean t=false;
				ras=new RandomAccessFile("user.txt","r");
				while((strUser=ras.readLine())!=null)
				{
					if(strUser.equals(txtUserName.getText()))
					{
						if(ras.readLine().equals(pwdPassword.getText()))
						{
							JOptionPane.showMessageDialog(null,"登录成功");
							t=true;
							break;
						}
					}
				}
				ras.close();
				if(t)
				{
					new Chat();
					this.dispose();
				}*/
		
			
		//	catch(Exception e){JOptionPane.showMessageDialog(null,"登录失败!");}
		
		}
		if(source==btnExit)
		{
			Object[] options={"是","否"};
			Object s=op1.showOptionDialog(null,"确认退出","提示",JOptionPane.DEFAULT_OPTION,JOptionPane.INFORMATION_MESSAGE,null,options,options[0]);
			int i=Integer.parseInt(s.toString());
			if(i==0)
			System.exit(0);
			
		}
		if(source==btnRegister)
		{
			new Register();
			this.dispose();
		}
	}
	public static void main(String args[]){
		new Login();	
	}
}