SpringWebSocket WebSocketConfigurer Arayüzü

Giriş
WebSocket çift yönlüdür. Aynı TCP bağlantısı gibidir. Açıklaması şöyle

WebSocket establishes a connection using a handshake request, after which the communication becomes bidirectional where there is no concept of response to a request.

Bağlantı bir kere kurulduktan sonra artık maliyeti yok gibidir. Açıklaması şöyle.

The crucial distinction between WebSockets and typical REST-based APIs is that clients based on the former protocol always establish long-running TCP connections and, once connected, the overhead they incur is practically negligible.

WebSockets streaming için tek yöntem değil. Açıklaması şöyle

Websockets, SSE (Server-sent Events) or XHR streaming are all good protocol choices for streaming updates in a browser.

Diğer 

Bu sınıfı kullanmak istemiyorsak şöyle yaparız. Burada direkt bir HandlerMapping  yani SimpleUrlHandlerMapping yaratılıyor.

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.reactive.HandlerMapping;
import org.springframework.web.reactive.handler.SimpleUrlHandlerMapping;
import org.springframework.web.reactive.socket.WebSocketHandler;

@Configuration
public class ReactiveServerWebSocketConfig {
  @Autowired
  private WebSocketHandler webSocketHandler;

  @Bean
  public HandlerMapping webSocketHandlerMapping() {
    Map<String, WebSocketHandler> map = new HashMap<>();
    map.put("/webflux", webSocketHandler);

    SimpleUrlHandlerMapping handlerMapping = new SimpleUrlHandlerMapping();
    handlerMapping.setOrder(-1);
    handlerMapping.setUrlMap(map);
    return handlerMapping;
  }
}

registerWebSocketHandlers metodu
Handler TextWebSocketHandler'dan kalıtan bir sınıf olabilir.
Handler AbstractWebSocketHandler'dan kalıtan bir sınıf olabilir.

Örnek
Şöyle yaparız

public class WebSocketConfiguration implements WebSocketConfigurer {
  
  @Override
  public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
    registry.addHandler(new WebSocketHandler(), "/presentation").setAllowedOrigins("*");
  }
}

Örnek - Interceptor
Şöyle yaparız.

@Configuration
@EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer {

  @Override
  public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
    registry.addHandler(myWebSocketController(), "/chat")
      .addInterceptors(new HttpSessionHandshakeInterceptor())
      .setAllowedOrigins("*");
  }

  @Bean
  public MyWebSocketController myWebSocketController() {
    return new MyWebSocketController();
  }
}

Örnek - SockJS
Şöyle yaparız.

@Configuration
@EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer
{
  @Override
  public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
    registry.addHandler(myHandler(), "/websocket").withSockJS();
  }

  @Bean
  public ServerHandler myHandler() {
    return new ServerHandler();
  }
}