การจัดการเหตุการณ์วงจรชีวิตของ WebSocket ใน Spring

A WebSocket connection moves through clear stages: it opens, exchanges messages, may hit errors, and finally closes. Spring lets you hook into each stage to manage state and resources cleanly.

This lesson covers handling those lifecycle events.

Spring's low-level API centers on the WebSocketHandler interface. Extending TextWebSocketHandler gives you override points for each lifecycle event without implementing every method.

afterConnectionEstablished fires when a client successfully connects. Use it to register the session and initialize per-connection state.

Keep active sessions in a thread-safe collection so you can broadcast and clean up. A ConcurrentHashMap keyed by session id is a common choice.

handleTextMessage runs for each incoming message. Here you parse, validate, and act on the payload, then optionally reply or broadcast.

handleTransportError is called when a low-level error occurs on the connection. Log the problem and close the session gracefully if it cannot recover.

afterConnectionClosed fires when the connection ends, whether the client left or the server closed it. Always clean up here to avoid leaks.

Close events carry a status code explaining why:

• 1000 Normal closure
• 1001 Going away (page unload)
• 1006 Abnormal closure (no close frame)
• 1011 Server error

Logging these helps diagnose connection problems.

Wire the handler to a path in a configuration class implementing WebSocketConfigurer.

Per-connection resources (timers, subscriptions, buffers) must be released on close and on error. Failing to do so causes memory leaks that grow with every dropped connection.

Dead connections may never fire a clean close. Use ping/pong heartbeats or idle timeouts to detect and reap stale sessions so your session map stays accurate.

You learned to handle the WebSocket lifecycle in Spring with TextWebSocketHandler: track sessions on connect, process messages, handle transport errors, and clean up on close. Close status codes, heartbeats, and idle timeouts keep your connection state healthy and leak-free.