File Sharing System

A lightweight, multithreaded TCP file-sharing system built in Java. It features both a modern JavaFX Graphical User Interface (GUI) client and a lightweight Command Line Interface (CLI) client, connected to a robust multithreaded backend server.

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Features

• Multithreaded Server: Handled using a cached thread pool to support multiple clients concurrently.
• JavaFX Desktop Client (GUI):
  • Clean, responsive dashboard with Search/Filter capability.
  • Displays actual file names and formatted sizes (e.g., KB, MB).
  • Real-time download/upload progress bars and system status indicators.
  • Fully constrained layout to prevent blank placeholder spaces or alignment errors.
• Command Line Client (CLI): Lightweight console interface to list, upload, and download files quickly.
• Strict Limits: Integrated safety safeguards such as a 50 MB upload limit per file to optimize server performance and storage.

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Project Structure

file-sharing-system/
├── src/
│   └── main/
│       ├── java/
│       │   ├── Server.java          # Server starter, listens on port 4000
│       │   ├── ClientHandler.java   # Runnable task handling single TCP client socket
│       │   ├── Launcher.java        # Workaround entrypoint for classpath launches
│       │   ├── Main.java            # Main JavaFX application window manager
│       │   ├── MainController.java  # Controller for GUI interactions, filters, and background threads
│       │   ├── FileItem.java        # Record modeling file metadata (name, size representation)
│       │   └── Client.java          # CLI client application
│       └── resources/
│           ├── main-view.fxml       # JavaFX structure layout
│           └── style.css            # Stylesheets for client custom design
├── server/                          # Folder created by the server containing shared files
├── pom.xml                          # Maven build configuration
└── README.md                        # Documentation

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System Architecture & Protocol

Clients communicate with the server over raw TCP sockets using a straightforward custom protocol:

• LIST:
  • Client sends: "LIST"
  • Server replies: A serialized string list of files and sizes formatted as "[filename1:size1, filename2:size2, ...]"
• UPLOAD:
  • Client sends: "UPLOAD" -> File Name (String) -> File Size in Bytes (int) -> Raw File Payload (bytes)
  • Server replies: None (Server streams bytes directly to disk)
• DOWNLOAD:
  • Client sends: "DOWNLOAD" -> File Name (String)
  • Server replies: File Size in Bytes (int; returns -1 if not found) -> Raw File Payload (bytes; if size > 0)
• EXIT:
  • Client sends: "EXIT" (Signals disconnection so server can clean up socket resources)

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Getting Started

To build and run the application, we recommend using an Integrated Development Environment (IDE) like IntelliJ IDEA, Eclipse, or NetBeans.

Prerequisites

• Java Development Kit (JDK) 17 or higher installed and configured in your IDE.

Loading the Project in your IDE

1. Open/Import the Project:

   • Open your IDE.
   • Select Open or Import Project and choose the root directory containing the pom.xml file.
   • The IDE will automatically read the configuration and set up the JavaFX project dependencies.

2. Wait for Synchronization:

   • Allow a moment for the IDE to finish syncing and download JavaFX modules.

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Running the Application from your IDE

You can run the server and client components directly from your IDE code explorer:

1. Start the Server:

   • Navigate to Server.java.
   • Right-click the file and select Run 'Server.main()'.
   • The server console will print that it has started listening on port 4000.

2. Start the GUI Client:

   • Navigate to Launcher.java.
   • Right-click the file and select Run 'Launcher.main()'.
   • The desktop file-sharing dashboard will open. Click Connect to link to the running server. You can click New Client to open additional independent client dashboards.

3. Start the CLI Client (Optional):

   • Navigate to Client.java.
   • Right-click the file and select Run 'Client.main()'.
   • Use the IDE terminal/console to interact with the text menu.

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Configuration and Notes

• Port Numbers: Default socket connection is bound to port 4000 (localhost:4000).
• File Upload Limits: A built-in validation cap restricts file sizes to 50 MB maximum to protect server storage.
• Download Storage:
  • GUI Client: Prompts you to pick a directory using a native file dialog.
  • CLI Client: Automatically saves downloaded files in a local folder named client_<port>/.