Add base files

2026-06-12 12:18:48 +03:30
commit 240eac0504
17 changed files with 530 additions and 0 deletions
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 target/
 !.mvn/wrapper/maven-wrapper.jar
 !**/src/main/**/target/
 !**/src/test/**/target/
 ### IntelliJ IDEA ###
 out/
 !**/src/main/**/out/
 !**/src/test/**/out/
 .kotlin
 .idea/modules.xml
 .idea/jarRepositories.xml
 .idea/compiler.xml
 .idea/libraries/
 *.iws
 *.iml
 *.ipr
 server_data/
 ### Eclipse ###
 .apt_generated
 .classpath
 .factorypath
 .project
 .settings
 .springBeans
 .sts4-cache
 bin/
 !**/src/main/**/bin/
 !**/src/test/**/bin/
 ### NetBeans ###
 /nbproject/private/
 /nbbuild/
 /dist/
 /nbdist/
 /.nb-gradle/
 ### VS Code ###
 .vscode/
 ### Mac OS ###
 .DS_Store
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 # Default ignored files
 /shelf/
 /workspace.xml
 # Ignored default folder with query files
 /queries/
 # Datasource local storage ignored files
 /dataSources/
 /dataSources.local.xml
 # Editor-based HTTP Client requests
 /httpRequests/
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 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
  <component name="Encoding">
    <file url="file://$PROJECT_DIR$/src/main/java" charset="UTF-8" />
    <file url="file://$PROJECT_DIR$/src/main/resources" charset="UTF-8" />
  </component>
 </project>
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 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
  <component name="ExternalStorageConfigurationManager" enabled="true" />
  <component name="MavenProjectsManager">
    <option name="originalFiles">
      <list>
        <option value="$PROJECT_DIR$/pom.xml" />
      </list>
    </option>
  </component>
  <component name="ProjectRootManager" version="2" project-jdk-name="25" project-jdk-type="JavaSDK">
    <output url="file://$PROJECT_DIR$/out" />
  </component>
 </project>
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 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
  <component name="VcsDirectoryMappings">
    <mapping directory="$PROJECT_DIR$" vcs="Git" />
  </component>
 </project>
@@ -0,0 +1,134 @@
 ## Network File-Sharing chat System (Java)
 ### Overview
 This project is a multi-client network chat system with file sharing, implemented using **Java sockets**, **MUltithreading** and **Object Serialization**.
 Clients connect to a central server and can:
 * send public chat message
 * send private messages
 * request the list of online users
 * transfer files to other users
 communication between client and server is implemented using Java Object Streams(`ObjectInputStream` / `ObjectOutputStream`) so that structured objects can be transferred directly over the network.
 ---
 ### Architecture
 1. **ChatServer** opens a `ServerSocket` and waits for connections.
 2. Each connecting client gets its own **ClientSession** thread.
 3. A shared **UserManager** tracks who's online and routes messages.
 4. Everything is exchanged as serialized objects (`ChatMessage` / `FileMessage`).
 ```
 Client  →  Socket  →  Server  →  ClientSession (thread)  →  UserManager  →  Broadcast/Route  →  Clients
 ```
 ---
 ### Message Protocol
 Two serializable classes carry everything over the wire:
 * **ChatMessage** – text-based: logins, public/private messages, user-list requests, server replies.
 * **FileMessage** – file transfers, carrying the file as a `byte[]`.
 `MessageType` is an enum (`LOGIN`, `LOGIN_SUCCESS`, `LOGIN_FAILED`, `PUBLIC_MESSAGE`, `PRIVATE_MESSAGE`, `USER_LIST`, …) so both sides agree on what each message means.
 ---
 ### Package Structure
 ```
 com.university.chat
 ├── common  → shared message classes (ChatMessage, FileMessage, MessageType)
 ├── server  → server-side logic
 └── client  → client application
 ```
 #### `common`
 Already complete — these define the protocol and don't need any changes.
 #### `server`
 * **ChatServer** – entry point. Opens the server socket and creates a `ClientSession` per client.
 * **ClientSession** – one thread per client. Handles login, reads incoming messages, and dispatches them (broadcast, private message, user list, file transfer).
 * **UserManager** – thread-safe registry of online users (`ConcurrentHashMap<String, ClientSession>`). Already complete.
 * **FileManager** – manages per-user folders on disk (`server_data/<username>/sent` and `received`). Already complete.
 #### `client`
 * **chatClient** – entry point. Connects to the server, logs in, starts a listener thread, and runs the input loop for user commands.
 * **ServerListener** – background thread that continuously reads and displays messages/files coming from the server.
 * **TransferProgress** – small helper that prints a progress bar during file uploads. Already complete.
 ---
 ### Client Commands
 ```
 /msg <username> <message>       → private message
 /users                          → list online users
 /sendfile <username> <filepath> → send a file
 <anything else>                 → public message
 ```
 ---
 ### File Transfer Flow
 1. Client reads the file and converts it to `byte[]`.
 2. It's wrapped in a `FileMessage` and sent to the server.
 3. The server saves a copy (in `sent/` for the sender, `received/` for the receiver) and forwards it to the recipient.
 ---
 ### Threading Model
 * **Server**: one `ClientSession` thread per connected client.
 * **Client**: main thread handles user input, a `ServerListener` thread handles incoming messages — so you can chat and receive **at the same time**.
 ---
 ## Your Task
 Several core pieces are left as **TODOs** for you to implement. Follow the comments in each file alongside the structure mentioned above to complete them.
 | File                         | What to implement                                                                                                                                                                                                                         |
 |------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
 | `Server/ChatServer.java`     | Pick a port, create a shared `UserManager`, open the server socket, accept clients in a loop, and create a `ClientSession` thread per client.                                                                                             |
 | `Server/ClientSession.java`  | Set up object streams in the constructor; handle login (success/failure); receive messages in a loop and dispatch `ChatMessage`/`FileMessage`; broadcast, private message, and user-list logic; remove user on disconnect; forward files. |
 | `Client/chatClient.java`     | Connect to the server, set up streams, log in, start `ServerListener`, and implement the command loop (`/msg`, `/users`, `/sendfile`, plain messages).                                                                                    |
 | `Client/ServerListener.java` | Continuously read objects from the server and print chat messages / file-received notifications.                                                                                                                                          |
 **Tips:**
 * Always create the `ObjectOutputStream` *before* the `ObjectInputStream` on both ends — this avoids a stream-handshake deadlock.
 * Don't forget `out.flush()` after `writeObject(...)`.
 * Test with two or more client instances to verify broadcasting, private messages, and file transfer all work correctly.
 #### Running multiple clients in IntelliJ
 1. Click the **⋮** icon next to the run button → **Edit Configurations**
 2. Open **Modify options** (Alt+M)
 3. Enable **Allow multiple instances** (Alt+U)
 ---
 ## Optional Bonus: JavaFX UI
 If you want to go further replace the console client with a simple **JavaFX** GUI (chat window, online-user list, file-send button, etc.).
 1. **Add the JavaFX dependencies** to your `pom.xml` —  for Maven:
   ```xml
   <dependency>
       <groupId>org.openjfx</groupId>
       <artifactId>javafx-controls</artifactId>
       <version>21</version>
   </dependency>
   <dependency>
       <groupId>org.openjfx</groupId>
       <artifactId>javafx-fxml</artifactId>
       <version>21</version>
   </dependency>
   ```
   You'll also need the `javafx-maven-plugin` to run the app from Maven.
 2. **Create a JavaFX entry point**, e.g. `Client/ChatClientApp.java`, extending `javafx.application.Application` and implementing `start(Stage stage)`. This becomes your new launch class instead of (or alongside) `chatClient`.
 3. Reuse your existing socket/streams logic — just move the "send" actions to button handlers and update the UI from `ServerListener` using `Platform.runLater(...)` (**since UI updates must happen on the JavaFX Application Thread**).
 This part is **completely optional** and won't affect your core grade — just a fun way to practice connecting a GUI to networking code and multithreading.
@@ -0,0 +1,17 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>socket</groupId>
    <artifactId>SocketProgramming</artifactId>
    <version>1.0-SNAPSHOT</version>
    <properties>
        <maven.compiler.source>25</maven.compiler.source>
        <maven.compiler.target>25</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
 </project>
@@ -0,0 +1,20 @@
 package com.university.chat.Client;
 public class ServerListener implements Runnable{
    // TODO: store the ObjectInputStream from the user socket
    //          (this should be the same input stream the
    //           chatClient created when connecting)
    @Override
    public void run() {
        try {
            // TODO: In an infinite loop read objects from the server
            //   - if it's a ChatMessage  -> print "<sender>: <content>"
            //   - if it's a FileMessage  -> print that a file was received
            //                               (filename + sender), it's already
            //                               saved to disk by the server.
        } catch (Exception e){
            System.out.println("Disconnected from server");
        }
    }
 }
@@ -0,0 +1,37 @@
 package com.university.chat.Client;
 public class TransferProgress {
    private final long total;
    private final long startTime;
    private static final int WIDTH = 30;
    public TransferProgress(long total) {
        this.total = total;
        this.startTime = System.currentTimeMillis();
    }
    public void update(long current) {
        double percent = (double) current / total;
        int filled = (int) (percent * WIDTH);
        StringBuilder bar = new StringBuilder("[");
        for (int i = 0; i < WIDTH; i++) {
            bar.append(i < filled ? "█" : " ");
        }
        bar.append("]");
        long elapsed = System.currentTimeMillis() - startTime;
        double speed = current / 1024.0 / 1024.0 / (elapsed / 1000.0 + 0.001);
        System.out.printf("\r%s %3d%% | %.2f MB/s",
                bar,
                (int) (percent * 100),
                speed);
        if (current >= total) {
            System.out.println();
        }
    }
 }
@@ -0,0 +1,29 @@
 package com.university.chat.Client;
 public class chatClient {
    public static void main() {
        // TODO: Connecting to the server
        //  1. Create a socket and connect to the server
        //  2. Create an ObjectOutputStream (out) and ObjectInputStream (in)
        //      from the socket's streams — output FIRST, then input.
        //  2. Get the username, and send a LOGIN ChatMessage with that username
        //  3. Start a new Thread running a ServerListener(in) so incoming
        //      messages are handled concurrently.
        while (true){
            try {
                // TODO: Program loop — read a line from the console and act on it:
                //   - "/msg <user> <text>"        -> build & send a PRIVATE_MESSAGE
                //   - "/users"                    -> build & send a USER_LIST request
                //   - "/sendfile <user> <path>"   -> read the file into a byte[]
                //                                     (you can use TransferProgress
                //                                     to show progress)
                //                                     and send it as a FileMessage
                //   - anything else               -> send a PUBLIC_MESSAGE
                //   Remember to flush() the output stream after writeObject().
            } catch (Exception e){
                System.out.println("command failed: " + e.getMessage());
            }
        }
    }
 }
@@ -0,0 +1,25 @@
 package com.university.chat.Common;
 import java.io.Serializable;
 public class ChatMessage implements Serializable {
    private static final long serialVersionUID = 1L;
    private MessageType type;
    private String sender;
    private String receiver;
    private String content;
    public ChatMessage(MessageType type, String sender, String receiver, String content) {
        this.type = type;
        this.sender = sender;
        this.receiver = receiver;
        this.content = content;
    }
    public MessageType getType() { return type; }
    public String getSender() { return sender; }
    public String getReceiver() { return receiver; }
    public String getContent() { return content; }
 }
@@ -0,0 +1,36 @@
 package com.university.chat.Common;
 import java.io.Serializable;
 public class FileMessage implements Serializable {
    private static final long SerialVersionUID = 1L;
    private String sender;
    private String receiver;
    private String filename;
    private byte[] data;
    public FileMessage(String sender, String receiver, String filename, byte[] data) {
        this.sender = sender;
        this.receiver = receiver;
        this.filename = filename;
        this.data = data;
    }
    public String getSender() {
        return sender;
    }
    public String getReceiver() {
        return receiver;
    }
    public String getFilename() {
        return filename;
    }
    public byte[] getData() {
        return data;
    }
 }
@@ -0,0 +1,13 @@
 package com.university.chat.Common;
 import java.io.Serializable;
 public enum MessageType implements Serializable {
    LOGIN,
    LOGIN_SUCCESS,
    LOGIN_FAILED,
    PUBLIC_MESSAGE,
    PRIVATE_MESSAGE,
    USER_LIST,
    FILE_TRANSFER
 }
@@ -0,0 +1,15 @@
 package com.university.chat.Server;
 public class ChatServer {
    // TODO: declare a single shared UserManager instance (static final)
    //         This MUST be shared by all ClientSession threads so that
    //         broadcasting and private messaging work correctly.
    public static void main(String[] args) {
        // TODO: Create a ServerSocket
        // TODO: In an infinite loop:
        //  accept an incoming client connection
        //  make a new thread running ClientSession for each user.
    }
 }
@@ -0,0 +1,71 @@
 package com.university.chat.Server;
 import com.university.chat.Common.ChatMessage;
 import com.university.chat.Common.FileMessage;
 import java.io.IOException;
 import java.net.Socket;
 import java.nio.file.Files;
 public class ClientSession implements Runnable {
    private String username;
    public ClientSession(Socket socket, UserManager userManager) {
        // TODO : Create an ObjectOutputStream from socket.getOutputStream()
        //         and an ObjectInputStream from socket.getInputStream().
    }
    @Override
    public void run() {
        try {
            // TODO: Welcome the user (login step)
            //  1. Read the first object sent by the client.
            //  2. Check it's a ChatMessage with type LOGIN.
            //  3. Extract the username.
            //  4. Try to register the user via userManager.addUser(...).
            //  5. If the username is taken, send back LOGIN_FAILED and close the socket.
            //  6. Otherwise, create the user's folders with FileManager.createUserFolders(...)
            //      and send back LOGIN_SUCCESS.
            // TODO: Main message loop
            //   In a loop, call in.readObject(), you can separate messages by their type:
            //     - if it's a ChatMessage      -> call handleChatMessage(msg)
            //     - if it's a FileMessage      -> call handleFileMessage(fileMsg)
            //   Keep looping until the connection is closed (an exception will be thrown).
        } catch (Exception e) {
            System.out.println("Disconnected: " + username);
        } finally {
            // TODO: Remove the user from UserManager so they no longer
            //        receive broadcasts or appear in users list
        }
    }
    private void handleChatMessage(ChatMessage msg) throws IOException {
        switch (msg.getType()) {
            case PUBLIC_MESSAGE -> {
                // TODO: Broadcast this message to every connected client.
            }
            case PRIVATE_MESSAGE -> {
                // TODO: Forward this message to the receiver user.
            }
            case USER_LIST -> {
                // TODO: Reply to the requester with the list of online users.
            }
        }
    }
    private void handleFileMessage(FileMessage fileMsg) throws IOException {
        // Storing the file
        var sentPath = FileManager.getSentPath(fileMsg.getSender(), fileMsg.getFilename());
        var recvPath = FileManager.getReceivedPath(fileMsg.getReceiver(), fileMsg.getFilename());
        Files.write(sentPath, fileMsg.getData());
        Files.write(recvPath, fileMsg.getData());
        // TODO: Forward the received file-message to the destination user.
    }
 }
@@ -0,0 +1,25 @@
 package com.university.chat.Server;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 public class FileManager {
    private static final String BASE_DIR = "server_data";
    public static void createUserFolders(String username) throws IOException {
        Path userPath = Paths.get(BASE_DIR, username);
        Files.createDirectories(userPath.resolve("received"));
        Files.createDirectories(userPath.resolve("sent"));
    }
    public static Path getReceivedPath(String username, String filename) {
        return Paths.get(BASE_DIR, username, "received", filename);
    }
    public static Path getSentPath(String username, String filename) {
        return Paths.get(BASE_DIR, username, "sent", filename);
    }
 }
@@ -0,0 +1,28 @@
 package com.university.chat.Server;
 import java.util.concurrent.ConcurrentHashMap;
 public class UserManager {
    private final ConcurrentHashMap<String, ClientSession> users = new ConcurrentHashMap<>();
    public boolean addUser(String username, ClientSession session) {
        return users.putIfAbsent(username, session) == null;
    }
    public void removeUser(String username) {
        users.remove(username);
    }
    public ClientSession getUser(String username) {
        return users.get(username);
    }
    public String listUsers() {
        return users.keySet().toString();
    }
    public Iterable<ClientSession> getAllSessions() {
        return users.values();
    }
 }