Java Networking Basics

1. Introduction

Java provides extensive networking capabilities through its java.net package. This lesson covers the basics of Java networking, including key concepts, socket programming, and how to create client-server applications.

2. Key Concepts

3. Socket Programming

Socket programming in Java involves creating a socket to establish a connection between a client and a server.

3.1 Creating a Socket

To create a socket, use the Socket class for the client and the ServerSocket class for the server.

import java.io.*;
import java.net.*;

public class Client {
    public static void main(String[] args) {
        try {
            Socket socket = new Socket("localhost", 12345);
            PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
            out.println("Hello Server!");
            socket.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}
                

3.2 Server Example

import java.io.*;
import java.net.*;

public class Server {
    public static void main(String[] args) {
        try {
            ServerSocket serverSocket = new ServerSocket(12345);
            Socket clientSocket = serverSocket.accept();
            BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
            String message = in.readLine();
            System.out.println("Received: " + message);
            clientSocket.close();
            serverSocket.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}
                

4. Server and Client

The server listens for incoming connections, while the client initiates a connection to the server.

graph TD;
                A[Client] -->|Connects to| B[Server];
                B -->|Accepts Connection| A;
                A -->|Send Data| B;
                B -->|Receives Data| A;
            

5. Best Practices

• Always close your sockets and streams to prevent resource leaks.
• Implement error handling to manage exceptions gracefully.
• Use threads to handle multiple clients simultaneously.
• Secure your application by validating input and using secure protocols.

6. FAQ