login.java

j2ee项目实例开发第七章的代码

//import classes

import java.io.*;
import java.net.*;
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
import java.util.*;
import javax.swing.Timer;

public class Login extends JFrame implements ActionListener
{

//declare components 

JLabel lblUserName;
JLabel lblUserPwd;
JTextField txtUsrName;
JPasswordField txtUsrPwd;
JButton btnLogin;
JButton btnCancel;
JButton btnRegister;
String UsrName;
char[] UsrPwd;
String strPwd;

Socket toServer;
ObjectInputStream streamFromServer;
PrintStream streamToServer;

 
 public Login()
 {
	this.setTitle("Login"); //set the title
        JPanel panel=new JPanel();
 	
 	panel.setLayout(new GridBagLayout());
 	GridBagConstraints gbCons=new GridBagConstraints();
	
	//place the components on the frame	
	gbCons.gridx=0;
	gbCons.gridy=0;
	lblUserName=new JLabel("Enter Username ");
	panel.add(lblUserName, gbCons);

	gbCons.gridx=1;
	gbCons.gridy=0;
	txtUsrName=new JTextField(20);
	panel.add(txtUsrName, gbCons);

	gbCons.gridx=0;
	gbCons.gridy=1;
	lblUserPwd=new JLabel("Enter Password ");
	panel.add(lblUserPwd, gbCons);

	gbCons.gridx=1;
	gbCons.gridy=1;
	txtUsrPwd=new JPasswordField(20);
	panel.add(txtUsrPwd, gbCons);
	
	JPanel btnPanel=new JPanel();
	btnLogin=new JButton("Login");
	btnPanel.add(btnLogin);
	btnLogin.addActionListener(this); //add listener to the Login button
	btnRegister=new JButton("Register");
	btnPanel.add(btnRegister);
	btnRegister.addActionListener(this); //add listener to the Register button
	btnCancel=new JButton("Cancel");
	btnPanel.add(btnCancel);
	btnCancel.addActionListener(this); //add listener to the Cancel button

	gbCons.gridx=1;
	gbCons.gridy=3;
	gbCons.anchor=GridBagConstraints.EAST;
	panel.add(btnPanel, gbCons);

	getContentPane().add(panel);
	setVisible(true);
	setSize(450,200);

        setDefaultCloseOperation(EXIT_ON_CLOSE);
    	
 }

//show the error message
void showdlg()
{
	JOptionPane.showMessageDialog(this,"Invalid Password or Login name", "Message", JOptionPane.ERROR_MESSAGE); 
}


public void actionPerformed(ActionEvent e1)
{
	JButton button=(JButton)e1.getSource();
	if(button.equals(btnCancel))
	{
		this.dispose(); //close the current frame
	}
	else if(button.equals(btnRegister))
	{
		new Register(); //call Register program
		this.dispose();
	}
	else
	{

	try
	{
		//create socket and input-output socket streams        
		toServer=new Socket("machine-name",1001);
        	streamFromServer=new ObjectInputStream(toServer.getInputStream());
        	streamToServer=new PrintStream(toServer.getOutputStream());
       
		//send message to server for login	
		streamToServer.println("LoginInfo");
		UsrName=txtUsrName.getText();
		UsrPwd=txtUsrPwd.getPassword();
		strPwd=new String(UsrPwd);
	
        	//send the user name and password to the server
		streamToServer.println(UsrName+":"+strPwd);
	
		//read the message from the server
		String frmServer=(String)streamFromServer.readObject();
		
		if(frmServer.equals("Welcome"))
		{
			new clientInt(UsrName); //start the chat screen
			this.dispose();
		}
		else
		{
			showdlg();//show error message	
		}

        }//end of try
	catch(Exception e)
	{
		System.out.println("Exception Occured: "+e);
	}
	}//end of if..else
}//end of actionPerformed






public static void main(String args[])
{
	new Login();
}
}//end of class Login