LoginGUI.java
完成效果如下图：
CODE
Summary:
This code sets up a login GUI using Swing.
It defines a LoginGUI class extending JFrame.
The constructor initializes the GUI components and sets up event listeners.
The event_login method handles the login logic, displaying messages based on the success or failure of the login attempt.
/*
package com.shiyanlou.view; - This declares the package name.
The import statements import various classes needed for the GUI components and event handling from the javax.swing and java.awt libraries, as well as a custom utility class JDOM.
*/
package com.shiyanlou.view;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JPasswordField;
import javax.swing.JTextField;
import javax.swing.border.EmptyBorder;
import com.shiyanlou.util.JDOM;
/Class Declaration
/*
LoginGUI extends JFrame, which means it is a type of window.
--
serialVersionUID is a unique identifier for the class, used during deserialization.
--
contentPane is a JPanel that acts as the main panel of the frame.
--
IDtxt, Passwdlabel, and passwordField are components for user input and labels.
--
login and back are buttons for submitting the login form and going back to the main window.
*/
public class LoginGUI extends JFrame {
private static final long serialVersionUID = 4994949944841194839L;
private JPanel contentPane; //面板
private JTextField IDtxt; //ID输入框
private JLabel Passwdlabel; //密码标签
private JPasswordField passwordField; //密码输入框
private JButton login;//登录按钮
private JButton back;//返回按钮
/ Member Method: loginGUI
/*
This method starts the application by creating and displaying the LoginGUI frame in the Event Dispatch Thread, ensuring thread safety.
*/
/*
*/
/**
* Launch the application.
* @return
*/
public void loginGUI() {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
LoginGUI frame = new LoginGUI();
frame.setVisible(true);
}catch(Exception e) {
e.printStackTrace();
}
}
});
}
Constructor: LoginGUI
/*
The constructor initializes the frame, sets the default close operation, size, and layout.
--
contentPane is set up as the main panel with a border and null layout for absolute positioning.
--
Labels and text fields (IDlabel, IDtxt, Passwdlabel, passwordField) are created and added to contentPane.
--
The login button is created, with mouse and key event listeners attached to handle clicks and Enter key presses.
--
The back button is created, with a mouse event listener to return to the main window.
A welcome label is added to the frame.
*/
//构造方法
/**
* Create the frame.
*/
public LoginGUI() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100,100,650,400);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5,5,5,5));
setContentPane(contentPane);
contentPane.setLayout(null);
JLabel IDlabel = new JLabel("Please input ID");//id 标签
IDlabel.setBounds(68,170,100,39);
contentPane.add(IDlabel);
IDtxt = new JTextField();
IDtxt.setBounds(220, 179, 126, 21);
contentPane.add(IDtxt);
IDtxt.setColumns(10);
Passwdlabel = new JLabel("Please input password");
Passwdlabel.setBounds(68, 219, 150, 50);
contentPane.add(Passwdlabel);
passwordField = new JPasswordField();
passwordField.setBounds(220, 234, 126, 21);
contentPane.add(passwordField);
login = new JButton("login");
//鼠标事件
login.addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent e) {
event_login();//登录事件方法
}
});
//键盘事件
login.addKeyListener(new KeyAdapter() {
public void keyPressed(KeyEvent e) {
if(e.getKeyCode() == KeyEvent.VK_ENTER) {//当键盘按enter时调用
event_login();//登录事件方
}
}
});
login.setBounds(239, 310, 93, 23);
contentPane.add(login);
//返回按钮
back = new JButton("BACK");
back.addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent e) {
IndexGUI.init();
setVisible(false);
}
});
back.setBounds(507, 310, 93, 23);
contentPane.add(back);
//标题
JLabel label = new JLabel("Welcome to use KnowYou");
label.setFont(new Font("Ubuntu",Font.BOLD | Font.ITALIC,30));
}
/event_login
/*
This method handles the login logic when the login button is clicked or Enter is pressed.
--
It retrieves the user ID and password from the input fields.
--
It calls JDOM.read(id, passwd) to validate the credentials.
--
If the login is successful, it displays a welcome message and opens the user GUI (UsersGUI.init(name)).
--
If the login fails, it shows an error message.
*/
//封装登录事件
private void event_login() {
//这里的登录事件方法暂不处理，日后补充。
String id = IDtxt.getText();
String passwd = new String(passwordField.getPassword());
String flag = JDOM.read(id, passwd);
if(flag.contains("Successful landing")) {
//拆分信息
String[] bufs = flag.split("/");
String name = bufs[1];
//提示框，打印登录成功
JOptionPane.showMessageDialog(contentPane, "Welcome: "+name,"Welcome", JOptionPane.PLAIN_MESSAGE);
UsersGUI.init(name);
setVisible(false);
}
else {
//提示框，错误信息
JOptionPane.showMessageDialog(contentPane, flag,"ERROR",JOptionPane.ERROR_MESSAGE);
}
}
}
tips:
understanding the details of the code is crucial for a Java developer. Knowing the specifics allows you to:
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debug effectively
-
write better code
-
understand others' code
-
optimize performance
-
implement features
Event Dispatch Thread
javaCopy codeEventQueue.invokeLater(new Runnable() {
public void run() {
try {
LoginGUI frame = new LoginGUI();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
-
Purpose: Ensures that the creation and updating of GUI components happen on the Event Dispatch Thread (EDT), which is the thread responsible for handling GUI events in Swing.
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Details
:
-
EventQueue.invokeLater(Runnable runnable): Schedules the specifiedRunnableto be executed on the EDT. -
new Runnable() { public void run() { ... } }: Defines theRunnable'srunmethod, which is executed on the EDT. -
LoginGUI frame = new LoginGUI();: Creates an instance ofLoginGUI. -
frame.setVisible(true);: Makes the frame visible.
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Constructor: LoginGUI
javaCopy codesetDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); setBounds(100, 100, 650, 400); contentPane = new JPanel(); contentPane.setBorder(new EmptyBorder(5, 5, 5, 5)); setContentPane(contentPane); contentPane.setLayout(null);
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Purpose: Sets up the main window and its content pane.
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Details
:
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setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);: Specifies that the application should exit when the window is closed. -
setBounds(int x, int y, int width, int height);: Sets the position and size of the frame. -
contentPane = new JPanel();: InitializescontentPane. -
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));: Adds an empty border with 5-pixel padding around thecontentPane. -
setContentPane(contentPane);: SetscontentPaneas the content pane for the frame. -
contentPane.setLayout(null);: Uses absolute positioning for the layout ofcontentPane.
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Adding Components
javaCopy codeJLabel IDlabel = new JLabel("Please input ID");
IDlabel.setBounds(68, 170, 100, 39);
contentPane.add(IDlabel);
IDtxt = new JTextField();
IDtxt.setBounds(220, 179, 126, 21);
contentPane.add(IDtxt);
IDtxt.setColumns(10);
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Purpose: Adds a label and a text field for user ID input.
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Details
:
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JLabel IDlabel = new JLabel("Please input ID");: Creates a label with the specified text. -
IDlabel.setBounds(int x, int y, int width, int height);: Sets the position and size of the label. -
contentPane.add(IDlabel);: Adds the label tocontentPane. -
IDtxt = new JTextField();: Creates a text field for user input. -
IDtxt.setBounds(int x, int y, int width, int height);: Sets the position and size of the text field. -
contentPane.add(IDtxt);: Adds the text field tocontentPane. -
IDtxt.setColumns(int columns);: Sets the number of columns in the text field, affecting its preferred width.
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Event Listeners
javaCopy codelogin.addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent e) {
event_login();
}
});
login.addKeyListener(new KeyAdapter() {
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_ENTER) {
event_login();
}
}
});
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Purpose: Attaches event listeners to the login button for handling mouse clicks and key presses.
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Details
:
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login.addMouseListener(new MouseAdapter() { ... });: Adds a mouse listener to handle mouse events. -
mouseClicked(MouseEvent e): Called when the login button is clicked. -
event_login();: Calls theevent_loginmethod to handle the login process. -
login.addKeyListener(new KeyAdapter() { ... });: Adds a key listener to handle key events. -
keyPressed(KeyEvent e): Called when a key is pressed while the login button is focused. -
if (e.getKeyCode() == KeyEvent.VK_ENTER) { ... }: Checks if the Enter key was pressed.
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Event Handling Method: event_login
javaCopy codeprivate void event_login() {
String id = IDtxt.getText();
String passwd = new String(passwordField.getPassword());
String flag = JDOM.read(id, passwd);
if (flag.contains("Successful landing")) {
String[] bufs = flag.split("/");
String name = bufs[1];
JOptionPane.showMessageDialog(contentPane, "Welcome: " + name, "Welcome", JOptionPane.PLAIN_MESSAGE);
UsersGUI.init(name);
setVisible(false);
} else {
JOptionPane.showMessageDialog(contentPane, flag, "ERROR", JOptionPane.ERROR_MESSAGE);
}
}
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Purpose: Handles the login process by validating user credentials.
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Details
:
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String id = IDtxt.getText();: Retrieves the user ID from the text field. -
String passwd = new String(passwordField.getPassword());: Retrieves the password from the password field. -
String flag = JDOM.read(id, passwd);: Calls a method fromJDOMto validate the credentials and returns a result string. -
if (flag.contains("Successful landing")) { ... }: Checks if the login was successful. -
String[] bufs = flag.split("/");: Splits the result string to extract the user's name. -
String name = bufs[1];: Gets the user's name. -
JOptionPane.showMessageDialog(contentPane, "Welcome: " + name, "Welcome", JOptionPane.PLAIN_MESSAGE);: Displays a welcome message. -
UsersGUI.init(name);: Initializes the user GUI with the user's name. -
setVisible(false);: Hides the login window. -
else { ... }: Displays an error message if the login failed.
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