如何在java spring websocket中实现乒乓球

Question

As per the documentation here https://tools.ietf.org/html/rfc6455#page-37 , a websocket must respond to a ping request with pong .

I have implemented spring boot websocket to handle the websocket connections from clients.

I have a websocket client implemented which sends ping frames periodically.

I found it here https://stackoverflow.com/a/24438328 that I cannot process ping messages in java.

I have queries regarding this -

1. Should I have to handle these ping requests in java spring-boot websocket ?
2. if yes how could I implement this in spring boot application and respond to a ping request with pong ?

Answer 1

Should I have to handle these ping requests in java spring-boot websocket?

No

The server will automatically reply with a pong.

For Tomcat see

https://github.com/apache/tomcat85/blob/b21d02042c408053a1944b27c3196ec9be3db381/java/org/apache/tomcat/websocket/WsFrameBase.java#L348

https://github.com/apache/tomcat85/blob/b21d02042c408053a1944b27c3196ec9be3db381/java/org/apache/tomcat/websocket/WsFrameBase.java#L41-L42

For Jetty

https://github.com/eclipse/jetty.project/blob/b0f34fec3f4156c6fb250132fe95a895e07fb5ae/jetty-websocket/websocket-common/src/main/java/org/eclipse/jetty/websocket/common/events/AbstractEventDriver.java#L125-L143

The ping is not exposed in the spring websocket handler (receive part)

With jetty it's possible to get notified for the ping (see org.eclipse.jetty.websocket.api.WebSocketPingPongListener )

But it's not used by spring-websocket.

Answer 2

Extend class TextWebSocketHandler and write your logic in handleTextMessage method. If you are looking for more generic approach look into WebSocketHandler interface. But as Antoniossss suggested ping pong is already implemented on protocol level for checking if connection is still alive.