编写一个简单的二级文件系统实现程序。要求模拟采用二级目录结构的磁盘文件系统的文件操作能实现相应的命令，用输入命令来模拟用户程序中调用的文件操作。如用一级目录创建用户、登录用户，用二级文件创建文件、删除文件和查询文件

import java.util.HashMap;
import java.util.Map;

class User {
    private String username;
    private String password;

    public User(String username, String password) {
        this.username = username;
        this.password = password;
    }

    // getters and setters
}

class File {
    private String name;

    public File(String name) {
        this.name = name;
    }

    // getters and setters
}

class Directory {
    private String name;
    private Map<String, File> files;

    public Directory(String name) {
        this.name = name;
        this.files = new HashMap<>();
    }

    public void createFile(String filename) {
        File file = new File(filename);
        files.put(filename, file);
        System.out.println("File created: " + filename);
    }

    public void deleteFile(String filename) {
        if (files.containsKey(filename)) {
            files.remove(filename);
            System.out.println("File deleted: " + filename);
        } else {
            System.out.println("File not found: " + filename);
        }
    }

    public void queryFile(String filename) {
        if (files.containsKey(filename)) {
            System.out.println("File found: " + filename);
        } else {
            System.out.println("File not found: " + filename);
        }
    }

    // getters and setters
}

class FileSystem {
    private Map<String, User> users;
    private Directory rootDirectory;
    private User currentUser;

    public FileSystem() {
        this.users = new HashMap<>();
        this.rootDirectory = new Directory("root");
        this.currentUser = null;
    }

    public void createUser(String username, String password) {
        if (users.containsKey(username)) {
            System.out.println("User already exists: " + username);
        } else {
            User user = new User(username, password);
            users.put(username, user);
            System.out.println("User created: " + username);
        }
    }

    public void loginUser(String username, String password) {
        if (users.containsKey(username)) {
            User user = users.get(username);
            if (user.getPassword().equals(password)) {
                currentUser = user;
                System.out.println("Logged in as user: " + username);
            } else {
                System.out.println("Invalid password for user: " + username);
            }
        } else {
            System.out.println("User not found: " + username);
        }
    }

    public void executeCommand(String command) {
        String[] parts = command.split(" ");
        String operation = parts[0];

        switch (operation) {
            case "createuser":
                if (parts.length == 3) {
                    createUser(parts[1], parts[2]);
                } else {
                    System.out.println("Invalid command format: " + command);
                }
                break;
            case "login":
                if (parts.length == 3) {
                    loginUser(parts[1], parts[2]);
                } else {
                    System.out.println("Invalid command format: " + command);
                }
                break;
            case "createfile":
                if (currentUser != null && parts.length == 2) {
                    rootDirectory.createFile(parts[1]);
                } else {
                    System.out.println("Invalid command or not logged in: " + command);
                }
                break;
            case "deletefile":
                if (currentUser != null && parts.length == 2) {
                    rootDirectory.deleteFile(parts[1]);
                } else {
                    System.out.println("Invalid command or not logged in: " + command);
                }
                break;
            case "queryfile":
                if (currentUser != null && parts.length == 2) {
                    rootDirectory.queryFile(parts[1]);
                } else {
                    System.out.println("Invalid command or not logged in: " + command);
                }
                break;
            default:
                System.out.println("Unknown command: " + command);
        }
    }
}

public class Main {
    public static void main(String[] args) {
        FileSystem fileSystem = new FileSystem();

        // Example commands
        fileSystem.executeCommand("createuser user1 password1");
        fileSystem.executeCommand("login user1 password1");
        fileSystem.executeCommand("createfile file1.txt");
        fileSystem.executeCommand("queryfile file1.txt");
        fileSystem.executeCommand("deletefile file1.txt");
        fileSystem.executeCommand("queryfile file1.txt");
    }
}