Graphical Login Page

Answers/40230212013/Graphical Login Page/.vscode/settings.json

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+{
+    "java.project.sourcePaths": ["src"],
+    "java.project.outputPath": "bin",
+    "java.project.referencedLibraries": [
+        "lib/**/*.jar"
+    ]
+}

Answers/40230212013/Graphical Login Page/README.md

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+## Getting Started
+
+Welcome to the VS Code Java world. Here is a guideline to help you get started to write Java code in Visual Studio Code.
+
+## Folder Structure
+
+The workspace contains two folders by default, where:
+
+- `src`: the folder to maintain sources
+- `lib`: the folder to maintain dependencies
+
+Meanwhile, the compiled output files will be generated in the `bin` folder by default.
+
+> If you want to customize the folder structure, open `.vscode/settings.json` and update the related settings there.
+
+## Dependency Management
+
+The `JAVA PROJECTS` view allows you to manage your dependencies. More details can be found [here](https://github.com/microsoft/vscode-java-dependency#manage-dependencies).

Answers/40230212013/Graphical Login Page/src/App.java

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+public class App {
+    public static void main(String[] args) {
+        LoginGUI loginGUI = new LoginGUI();
+        loginGUI.setVisible(true);
+    }
+}

Answers/40230212013/Graphical Login Page/src/EmailValidator.java

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+import java.util.regex.Pattern;
+
+public class EmailValidator {
+    private static final Pattern EMAIL_PATTERN = Pattern.compile(
+            "^[A-Za-z0-9+_.-]+@[A-Za-z0-9.-]+$"
+    );
+
+    public static boolean isValid(String email) {
+        return EMAIL_PATTERN.matcher(email).matches();
+    }
+}

Answers/40230212013/Graphical Login Page/src/LoginGUI.java

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+import javax.swing.*;
+import java.awt.*;
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+public class LoginGUI extends JFrame{
+  private JTextField usernameField;
+  private JPasswordField passwordField;
+  private JTextField emailField;
+  private JLabel message;
+  private UserStore userStore;
+
+  public LoginGUI()
+  {
+
+    setTitle("Login and Registration");
+    setSize(400, 300);    userStore = new UserStore();
+    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+    setLocationRelativeTo(null);
+    JPanel panel = new JPanel(new GridLayout(7, 1));
+    usernameField = new JTextField();
+    passwordField = new JPasswordField();
+    emailField = new JTextField();
+    message = new JLabel();
+    JButton login = new JButton("Login");
+    JButton register = new JButton("Register");
+
+    panel.add(new JLabel("Username:"));
+    panel.add(usernameField);
+    panel.add(new JLabel("Password:"));
+    panel.add(passwordField);
+    panel.add(new JLabel("Email:"));
+    panel.add(emailField);
+    panel.add(message);
+    panel.add(login);
+    panel.add(register);
+    add(panel);
+
+    login.addActionListener(new ActionListener() {
+      @Override
+      public void actionPerformed(ActionEvent e)
+      {
+        String username = usernameField.getText();
+        String password = new String(passwordField.getPassword());
+        if(UserStore.login(username, password))
+        {
+          message.setText("Login successful");
+        }
+        else
+        {
+          message.setText("Invalid username or password.");
+        }
+      }
+    });
+    register.addActionListener(new ActionListener() {
+      @Override
+      public void actionPerformed(ActionEvent e)
+      {
+        String username = usernameField.getText();
+        String password = new String(passwordField.getPassword());
+        String email = emailField.getText();
+      if(!EmailValidator.isValid(email))
+      {
+        message.setText("Invalid Email format!");
+        return;
+      }
+      int passwordStrength = PasswordUtils.isStrong(password);
+      if (passwordStrength < 3) {
+          message.setText("Weak password. Strength level: " + passwordStrength);
+          return;
+      }
+
+      User user = new User(username, password, email);
+        if(UserStore.register(user))
+        {
+          message.setText("Register successful!");
+        }
+        else
+        {
+          message.setText("User exists!");
+        }
+
+    }
+    });
+  }
+}

Answers/40230212013/Graphical Login Page/src/PasswordUtils.java

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+import java.util.regex.Pattern;
+
+public class PasswordUtils {
+  private static final Pattern specialChar = Pattern.compile("[@\\-_.]");
+  private static final Pattern Lowercase = Pattern.compile("[a-z]");
+  private static final Pattern Uppercase = Pattern.compile("[A-Z]");
+  private static final Pattern Digit = Pattern.compile("\\d");
+  public static int isStrong(String password)
+  {
+    int strength = 0;
+    if(password.length()<= 8)
+    {
+      strength++;
+    }
+    boolean lower = Lowercase.matcher(password).find();
+    boolean upper = Uppercase.matcher(password).find();
+    boolean digit = Digit.matcher(password).find();
+    boolean special = specialChar.matcher(password).find();
+    if(lower || upper || digit)
+    {
+      strength++;
+    }
+    if(lower && upper)
+    {
+      strength++;
+    }
+    if(lower && upper && digit)
+    {
+      strength++;
+    }
+    if(special)
+  {
+    strength++;
+  }
+  return strength;
+  }
+}

Answers/40230212013/Graphical Login Page/src/User.java

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+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+
+public class User {
+  private String username;
+  private String hashPassword;
+  private String email;
+  public User(String username, String password, String email)
+  {
+    this.username = username;
+    this.hashPassword = hashPassword(password);
+    this.email = email;
+  }
+  public String getUsername() {
+    return username;
+  }
+  public String getHashPassword() {
+    return hashPassword;
+  }
+  public String getEmail() {
+    return email;
+  }
+   public static String hashPassword(String password)
+  {
+  try
+  {
+    MessageDigest digest = MessageDigest.getInstance("SHA-256");
+    byte[] hash = digest.digest(password.getBytes());
+    StringBuilder str = new StringBuilder();
+    for(byte b : hash)
+    {
+      str.append(String.format("%02x", b));
+    }
+    return str.toString();
+  }
+  catch(NoSuchAlgorithmException e)
+  {
+    throw new RuntimeException(e);
+  }
+}
+}

Answers/40230212013/Graphical Login Page/src/UserStore.java

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+import java.util.HashMap;
+import java.util.Map;
+import java.io.*;
+public class UserStore {
+  private static final String file = "users.txt";
+  private static Map<String, User> users = new HashMap<>();
+  public UserStore()
+  {
+    loadUsers();
+  }
+  public static boolean register(User user)
+  {
+    if(users.containsKey(user.getUsername()))
+    {
+      return false;
+    }
+    users.put(user.getUsername(), user);
+    saveUsers();
+    return true;
+  }
+  public static boolean login(String username, String password)
+  {
+    User user = users.get(username);
+    if (user == null)
+    {
+      return false;
+    }
+    String hashPassword = User.hashPassword(password);
+    return hashPassword.equals(user.getHashPassword());
+  }
+  private void loadUsers()
+  {
+    try(BufferedReader bufr = new BufferedReader(new FileReader(file)))
+    {
+      String line;
+      while ((line = bufr.readLine()) != null) 
+      {
+        String[] parts = line.split(",");
+        if(parts.length == 3)
+        {
+          User user = new User(parts[0], parts[1], parts[2]);
+          users.put(user.getUsername(), user);
+        }
+      }
+    }
+    catch(IOException e)
+    {
+      e.printStackTrace();
+    }
+  }
+  private static void saveUsers()
+  {
+  try(BufferedWriter bufw = new BufferedWriter(new FileWriter(file)))
+  {
+    for(User user : users.values())
+    {
+      bufw.write(user.getUsername() + "," + user.getHashPassword() + "," + user.getEmail());
+      bufw.newLine();
+    }
+  }
+  catch(IOException e)
+  {
+    e.printStackTrace();
+  }
+}
+}

Answers/40230212013/Graphical Login Page/users.txt

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+navid,e9ff6b954d2c80dde0ac488c7962ae3604ff633770b130d8aea86b5c9482e5fe,navid@gmail.com