Connecting Server

To connect to a server in Java, you can use either **IP-based socket connections** (TCP/UDP) for real-time communication (like games) or **HTTP-based connections** (REST/WebSocket) for web APIs. Below are examples for both approaches:

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## **1. Connecting via IP (Socket Programming)**

Best for **real-time applications** like multiplayer games, chat apps, or low-latency services.

### **Example: TCP Socket Connection (Client-Side)**

```java

import java.io.*;

import java.net.*;

public class SocketClient {

    public static void main(String[] args) {

        String serverIP = "192.168.1.100"; // Replace with server IP

        int serverPort = 8080; // Replace with server port

        try (Socket socket = new Socket(serverIP, serverPort);

             PrintWriter out = new PrintWriter(socket.getOutputStream(), true);

             BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()))) {

            // Send a message to the server

            out.println("Hello Server!");

            // Read server response

            String response = in.readLine();

            System.out.println("Server says: " + response);

        } catch (UnknownHostException e) {

            System.err.println("Unknown host: " + serverIP);

        } catch (IOException e) {

            System.err.println("Connection error: " + e.getMessage());

        }

    }

}

```

#### **Key Points:**

- Uses `Socket` for **TCP/IP** communication.

- Best for **real-time** applications (games, chat).

- Requires the server to be running a **SocketServer** (`ServerSocket` in Java).

---

## **2. Connecting via HTTP (URLConnection / HttpClient)**

Best for **web APIs**, REST services, or when connecting to a **website (HTTP/HTTPS)**.

### **Example 1: Using `HttpURLConnection` (Basic HTTP GET)**

```java

import java.io.*;

import java.net.*;

public class HttpClientExample {

    public static void main(String[] args) {

        String url = "http://www.example.com/api/data"; // Replace with your URL

        try {

            URL serverUrl = new URL(url);

            HttpURLConnection conn = (HttpURLConnection) serverUrl.openConnection();

            conn.setRequestMethod("GET");

            // Read response

            int responseCode = conn.getResponseCode();

            System.out.println("Response Code: " + responseCode);

            BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));

            String inputLine;

            StringBuilder response = new StringBuilder();

            while ((inputLine = in.readLine()) != null) {

                response.append(inputLine);

            }

            in.close();

            System.out.println("Response: " + response.toString());

        } catch (IOException e) {

            System.err.println("HTTP Request Failed: " + e.getMessage());

        }

    }

}

```

### **Example 2: Using `HttpClient` (Java 11+)**

```java

import java.net.URI;

import java.net.http.HttpClient;

import java.net.http.HttpRequest;

import java.net.http.HttpResponse;

public class ModernHttpClient {

    public static void main(String[] args) throws Exception {

        String url = "http://www.example.com/api/data";

        HttpClient client = HttpClient.newHttpClient();

        HttpRequest request = HttpRequest.newBuilder()

                .uri(URI.create(url))

                .GET()

                .build();

        HttpResponse<String> response = client.send(

                request,

                HttpResponse.BodyHandlers.ofString()

        );

        System.out.println("Status Code: " + response.statusCode());

        System.out.println("Response Body: " + response.body());

    }

}

```

#### **Key Points:**

- Uses **HTTP/HTTPS** protocol (works with websites & APIs).

- Supports **GET, POST, PUT, DELETE** methods.

- `HttpClient` (Java 11+) is **more modern** than `HttpURLConnection`.

---

## **Which One Should You Use?**

| Feature | **IP (Socket)** | **HTTP** |

|---------|--------------|--------|

| **Use Case** | Real-time (games, chat) | Web APIs, REST services |

| **Protocol** | TCP/UDP | HTTP/HTTPS |

| **Latency** | Low (good for games) | Higher (depends on HTTP overhead) |

| **Security** | Needs manual encryption (SSL/TLS) | Built-in HTTPS support |

| **Complexity** | More code (manual packet handling) | Easier (structured requests) |

### **Recommendation:**

- **For games → Use Sockets (TCP/UDP).**

- **For web APIs → Use HTTP (HttpClient).**

Would you like a **full server-side example** (Java Socket Server or HTTP Server) to test these connections? 🚀