login.java

学习参考,java基本语法练习,包括一些常用的技巧

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.net.*;
import java.io.*;
import java.util.*;
public class  Login extends JFrame  implements ActionListener
{
	JPanel  pnlLogin;
 	JButton  btnLogin,btnRegister,btnExit;
	JLabel  lblServer,lblUserName,lblPassword,lblLogo;
	JTextField  txtUserName,txtServer;
	JPasswordField pwdPassword;
	String  strServerIp;
   //用于将窗口定位
	Dimension scrnsize;
	Toolkit toolkit=Toolkit.getDefaultToolkit();
	//构造方法           	   
	public Login()
	{
		//此处为布局组件代码
				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');
		/*  该布局采用手动布局           *
		 *　setBounds设置组件位置        *
		 *  setFont设置字体、字型、字号  *
		 *　setForeground设置文字的颜色  *
		 *  setBackground设置背景色      *
		 *  setOpaque将背景设置为透明    */
		pnlLogin.setLayout(null);  //组件用手动布局
		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("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("appico.jpg");
        setIconImage(img);			
		//三个按钮注册监听
		btnLogin  .addActionListener(this);
		btnRegister.addActionListener(this);
		btnExit   .addActionListener(this);
	}  //构造方法结束
	//按钮监听响应
	public void actionPerformed(ActionEvent ae)
	{
		Object source=ae.getSource();
		if (source.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");
            }
            else
		    {
			    strServerIp=txtServer.getText();
			    login();
		    }
		}
		if (source.equals(btnRegister))
		{
		    strServerIp=txtServer.getText();
		    this.dispose();
		    //进入注册界面
		}
		if (source == btnExit)
		{
		    System.exit(0);
		}
	}  
		
	//////////登录事件响应方法//////////
	public void login()
	{
		//该处为登录逻辑实现代码
	}   	
	public static void main(String args[])
	{
		new Login();
	}
	
}