springboot websocket do not work @Autowired

Question

In this class @Autowired is work

@Configuration
@EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer {

    @Autowired
    private UserDAO userDAO; // is NOT null

    @Autowired
    private IArticleService articleService; // is NOT null

    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
        registry.addHandler(new SocketTextHandler(), "/user").addInterceptors(new HttpHandshakeInterceptor());
    }
}

In this class @Autowired is NOT work

public class HttpHandshakeInterceptor implements HandshakeInterceptor {

      @Autowired
      private IArticleService articleService; // is null

      @Autowired
      private UserDAO userDAO; // is null

    public void afterHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Exception ex) {

    }

Maybe this is something like a channel wss?

You used the `new` keyword within `addInterceptors()` and thus, `HttpHandshakeInterceptor` is not a Spring managed bean. Add `@Component` to the interceptor, autowire it within `WebSocketConfig` and use that autowired field within `addInterceptors()`. More of that is explained within https://stackoverflow.com/questions/19896870/why-is-my-spring-autowired-field-null — g00glen00b, Sep 25 '18 at 11:13

score 2 · Answer 1 · answered Sep 25 '18 at 20:57

Your HttpHandshakeInterceptor instance is not managed by Spring (i.e. you are creating your instance with new).

You have two options here:

1. Make HttpHandshakeInterceptor Accept Parameters of type UserDAO and IArticleService

public class HttpHandshakeInterceptor implements HandshakeInterceptor {

      private IArticleService articleService;

      private UserDAO userDAO;

      public HttpHandshakeInterceptor(UserDAO userDAO, IArticleService articleService){
          this.userDAO = userDAO;
          this.articleService = articleService;
      }

    public void afterHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Exception ex) {

    }

Put @Component on top of HttpHandshakeInterceptor

@Component
public class HttpHandshakeInterceptor implements HandshakeInterceptor {

    @Autowired
    private IArticleService articleService; // is null

    @Autowired
    private UserDAO userDAO; // is null

    public void afterHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Exception ex) {

    }
}

and use @Autowired in your configuration:

@Configuration
@EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer {

    @Autowired
    private UserDAO userDAO;

    @Autowired
    private IArticleService articleService;

    @Autowired
    private HttpHandshakeInterceptor interceptor;

    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
        registry.addHandler(new SocketTextHandler(), "/user").addInterceptors(interceptor);
    }
}

You can also achieve what you achieved by @Component annotation with a @Bean definition in one of your @Configuration files.

Additionally, you can also go the route of @Configurable, but from what I see, you don't seem to need it at this point.

springboot websocket do not work @Autowired

1 Answers1