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/
@@ -0,0 +1,7 @@
+<?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>
@@ -0,0 +1,14 @@
+<?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>
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$" vcs="Git" />
+  </component>
+</project>
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+## 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.
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+<?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>
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+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");
+        }
+    }
+}
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+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();
+        }
+    }
+}
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+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; }
+}
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+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();
+    }
+}