Java Swing TCP Chat Application

Overview

This is a simple client-server chat application written in plain Java (no external frameworks). It uses TCP sockets and a multi-threaded server. The client GUI uses Java Swing.

Components

• Server.java - TCP server that accepts multiple clients and broadcasts messages.
• ClientHandler.java - Per-client handler running on its own thread.
• ClientGUI.java - Java Swing GUI for chat clients.
• ChatClient.java - Small launcher that starts the GUI.
• DBHelper.java - Optional MySQL helper to save chat history (disabled if config is empty).
• sql/create_table.sql - SQL to create the chat_history table.

Requirements

• Java 8 or newer
• Optional: MySQL and MySQL JDBC driver on classpath (for DB logging)

How it works

1. Start the server first:
   • java Server [port]
   • Default port is 12345
2. Start one or more clients:
   • java ChatClient
   • Fill username, server host (default localhost) and port (default 12345). Click Connect.
3. Type messages and click Send. Messages are broadcast to all connected clients.

Compilation (simple)

From the project folder run:

javac *.java

Then start the server:

java Server

And start clients (each in its own terminal / run):

java ChatClient

MySQL (optional)

If you want server to save chat history to MySQL:

1. Install MySQL and create a database (e.g., chatdb).

2. Run the SQL in sql/create_table.sql to create the chat_history table.

3. Edit DBHelper.java and set DB_URL, DB_USER, DB_PASSWORD appropriately.

4. Ensure MySQL JDBC driver (mysql-connector-java) is on the classpath when running the server:

   java -cp ".;path/to/mysql-connector-java.jar" Server

Notes

• The protocol is simple: client sends the username as the first line after connecting. After that every line is a message.
• The server broadcasts messages as: [username]: message
• Console logs include tags like [Server] and [Client].

Enjoy!