Getting a Failed to start bean 'subProtocolWebSocketHandler' exception while trying to implement websockets

问题

I am going through the websockets with Spring 4 tutorial here. I have it working where the server responds when client calls.

However, my use case is having the server push the messages without client having to call. So I looked up online on ways to do that and came across a few posts that said that I needed to use something called SimpMessagingTemplate. So I changed the code to use the SimpMessagingTemplate.

Now I get this exception in the server console:

04-Jun-2016 22:49:24.093 SEVERE [ContainerBackgroundProcessor[StandardEngine[Catalina]]] org.springframework.web.context.ContextLoader.initWebApplicationContext Context initialization failed
 org.springframework.context.ApplicationContextException: Failed to start bean 'subProtocolWebSocketHandler'; nested exception is java.lang.IllegalArgumentException: No handlers
        at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:176)
        at org.springframework.context.support.DefaultLifecycleProcessor.access$200(DefaultLifecycleProcessor.java:51)
        at org.springframework.context.support.DefaultLifecycleProcessor$LifecycleGroup.start(DefaultLifecycleProcessor.java:346)
        at org.springframework.context.support.DefaultLifecycleProcessor.startBeans(DefaultLifecycleProcessor.java:149)
        at org.springframework.context.support.DefaultLifecycleProcessor.onRefresh(DefaultLifecycleProcessor.java:112)
        at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:852)
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:541)
        at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:444)
        at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:326)
        at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:107)
        at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4809)
        at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5251)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)
        at org.apache.catalina.core.StandardContext.reload(StandardContext.java:3827)
        at org.apache.catalina.loader.WebappLoader.backgroundProcess(WebappLoader.java:291)
        at org.apache.catalina.core.StandardContext.backgroundProcess(StandardContext.java:5608)
        at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1377)
        at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1381)
        at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1381)
        at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1349)
        at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.IllegalArgumentException: No handlers
        at org.springframework.util.Assert.isTrue(Assert.java:68)
        at org.springframework.web.socket.messaging.SubProtocolWebSocketHandler.start(SubProtocolWebSocketHandler.java:251)
        at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:173)
        ... 20 more

I found this post and this post with the same issue but none of them have a real solution posted.

My websocket controller:

@Controller
public class WebSockController {

    private SimpMessagingTemplate template;

    @Autowired
    public WebSockController(SimpMessagingTemplate template) {
        this.template = template;
    }

    @MessageMapping("/hello")    
    public void greeting(GreetingsFromClient message) throws Exception {
        String[] messages = {"message1","message2","message3","message4","message5"};
        for(int i=0 ; i<messages.length ; i++){
            Thread.sleep(3000); // simulated delay
            this.template.convertAndSend("/topic/greetings", new GreetingsFromServer("Hello, " + messages[i] + "!"));
        }        
    }
}

My websocket config:

@Configuration
@EnableWebSocketMessageBroker
public class WebSocketConfig  implements WebSocketMessageBrokerConfigurer  {

    @Override
    public void configureMessageBroker(MessageBrokerRegistry config) {
        config.enableSimpleBroker("/topic");
        config.setApplicationDestinationPrefixes("/app");
    }

    @Override
    public void registerStompEndpoints(StompEndpointRegistry registry) {
        registry.addEndpoint("/hello").withSockJS();
    }

    @Override
    public void addArgumentResolvers(List<HandlerMethodArgumentResolver> arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void configureClientInboundChannel(ChannelRegistration arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void configureClientOutboundChannel(ChannelRegistration arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public boolean configureMessageConverters(List<MessageConverter> arg0) {
        // TODO Auto-generated method stub
        return true;
    }

    @Override
    public void configureWebSocketTransport(WebSocketTransportRegistration arg0) {
        // TODO Auto-generated method stub

    }
}

Also I had to add org.springframework.web.socket.config to component scan because without this I would get an auto-wiring exception (ref).

I am using Spring 4.2.5 and Tomcat 8.

Any help is appreciated. Please let me know if you need more info. Thanks.

回答1:

After struggling with this problem for a few hours, I resolved this by adding the websocket config to the rootconfig.

@Configuration
@ComponentScan({ "xxxxxx.xxxxxxxxx.controllers" })
@Import({SecurityConfig.class, WebSocketConfig.class, HibernateConfig.class})
public class RootConfig {

}

My application initializer that uses the root config.

public class WebApplicationInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {

    @Override
    protected Class<?>[] getRootConfigClasses() {
        return new Class[] { RootConfig.class };
    }

    @Override
    protected Class<?>[] getServletConfigClasses() {
        return new Class[] { AppConfig.class };
    }

    @Override
    protected String[] getServletMappings() {
        return new String[] { "/" };
    }
}

来源：https://stackoverflow.com/questions/37638396/getting-a-failed-to-start-bean-subprotocolwebsockethandler-exception-while-try