Java websockets examples

Java websockets examples

Here are some Java WebSocket examples:

Example 1: Simple Echo Server

In this example, we create a simple WebSocket server that echoes back any messages it receives from clients.

import javax.websocket.*;
import java.io.IOException;
@ServerEndpoint("/echo")
public class EchoServer {
@OnMessage
public void handleMessage(String message, Session session) throws IOException {
session.getBasicRemote().sendText(message);
}
}

Example 2: Chat Application

In this example, we create a simple chat application that allows multiple clients to communicate with each other.

import javax.websocket.*;
import java.io.IOException;
@ServerEndpoint("/chat")
public class ChatServer {
private static final Set sessions = new HashSet<>();
@OnOpen
public void onOpen(Session session) {
sessions.add(session);
}
@OnMessage
public void handleMessage(String message, Session session) throws IOException {
for (Session s : sessions) {
if (!s.equals(session)) {
s.getBasicRemote().sendText(message);
}
}
}
@OnClose
public void onClose(Session session) {
sessions.remove(session);
}
}

Example 3: Broadcasting Messages

In this example, we create a server that can broadcast messages to all connected clients.

import javax.websocket.*;
import java.io.IOException;
@ServerEndpoint("/broadcast")
public class Broadcaster {
private static final Set sessions = new HashSet<>();
@OnOpen
public void onOpen(Session session) {
sessions.add(session);
}
@OnMessage
public void handleMessage(String message, Session session) throws IOException {
for (Session s : sessions) {
s.getBasicRemote().sendText(message);
}
}
@OnClose
public void onClose(Session session) {
sessions.remove(session);
}
}

Example 4: Handling Errors

In this example, we create a server that handles errors by sending an error message to all connected clients.

import javax.websocket.*;
import java.io.IOException;
@ServerEndpoint("/error")
public class ErrorHandler {
private static final Set sessions = new HashSet<>();
@OnOpen
public void onOpen(Session session) {
sessions.add(session);
}
@OnMessage
public void handleMessage(String message, Session session) throws IOException {
try {
// process message
} catch (IOException e) {
sendError(session, e.getMessage());
}
}
@OnClose
public void onClose(Session session) {
sessions.remove(session);
}
private void sendError(Session session, String errorMessage) throws IOException {
session.getBasicRemote().sendText(errorMessage);
}
}

Example 5: Handling Multiple Types of Messages

In this example, we create a server that can handle different types of messages (e.g. text, binary).

import javax.websocket.*;
import java.io.IOException;
import java.util.UUID;
@ServerEndpoint("/multi-type")
public class MultiTypeHandler {
private static final Set sessions = new HashSet<>();
@OnOpen
public void onOpen(Session session) {
sessions.add(session);
}
@OnMessage
public void handleMessage(String message, Session session) throws IOException {
// handle text messages
}
@OnMessageBytes
public void handleBinaryMessage(Bytes message, Session session) throws IOException {
// handle binary messages
}
}

These are just a few examples of how you can use Java WebSockets to create different types of applications. The possibilities are endless!

java websocket example

Here's an example of a simple Java-based WebSocket server using the javax.websocket API and a WebSocket client implemented in JavaScript:

Java WebSocket Server (EchoServer.java)

import javax.websocket.*;
import javax.websocket.server.*;
@ServerEndpoint("/echo")
public class EchoServer {
@OnOpen
public void handleConnection(SESSION session) {
System.out.println("Client connected");
}
@OnMessage
public String receiveTextMessage(String message, SESSION session) {
System.out.println("Received: " + message);
return message;
}
@OnError
public void handleException(Throwable throwable) {
System.out.println("Error occurred: " + throwable.getMessage());
}
@OnClose
public void handleClose(SESSION session) {
System.out.println("Client disconnected");
}
}

JavaScript WebSocket Client (index.html)

WebSocket Example

How it works:

Note: In order for this example to work, you'll need to:

This example demonstrates the basic principles of WebSocket communication: establishing connections, sending messages, and handling disconnections. You can modify this example to build more complex applications or services.

References: