Question

我在使用带有@ServerEndPoint注释类的spring时遇到了麻烦

我正在使用Springboot 1.2.3，而我正在试图找出如何拥有端点的单个实例

@SpringBootApplication
@EnableJpaRepositories
@EnableWebSocket
public class ApplicationServer {
    public static void main(String[] args) {
        SpringApplication.run(ApplicationServer.class, args);
    }
}

Spring配置：

@ConditionalOnWebApplication
@Configuration
public class WebSocketConfigurator {

    @Bean
    public ServerEndPoint serverEndpoint() {
        return new ServerEndPoint();
    }

    @Bean
    public ServerEndpointExporter serverEndpointExporter() {
        return new ServerEndpointExporter();
    }
}

WebSocket端点：

@ServerEndpoint(value = "/", decoders = MessageDecoder.class, 
encoders = MessageEncoder.class, configurator = SpringConfigurator.class)
public class ServerEndPoint {

    private static final Logger LOG = LoggerFactory.getLogger(ServerEndPoint.class);

    public static final Set<CommunicationObserver> OBSERVERS = Sets.newConcurrentHashSet();

    @OnMessage
    public void onMessage(Session session, Message msg) {
        LOG.debug("Received msg {} from {}", msg, session.getId());
        for (CommunicationObserver o : OBSERVERS) {
            o.packetReceived(session, msg);
        }
    }

这基于Spring WebSocket JSR-356 tutorial，但我遇到以下错误：

java.lang.IllegalStateException: Failed to find the root WebApplicationContext. Was ContextLoaderListener not used?
    at org.springframework.web.socket.server.standard.SpringConfigurator.getEndpointInstance(SpringConfigurator.java:68)
    at org.apache.tomcat.websocket.pojo.PojoEndpointServer.onOpen(PojoEndpointServer.java:50)
    at org.apache.tomcat.websocket.server.WsHttpUpgradeHandler.init(WsHttpUpgradeHandler.java:138)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:687)
    at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:223)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1558)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1515)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)

我已经在嵌入模式和外部tomcat 8和jetty 9中测试过（在外部模式下，我删除了de Spring配置文件），但出现了相同的错误。

the only workaround i've found is to create a custom configurator.

public class SpringEndpointConfigurator extends ServerEndpointConfig.Configurator {

    private static WebApplicationContext wac;

    public SpringEndpointConfigurator() {
    }

    public SpringEndpointConfigurator(WebApplicationContext wac) {
        SpringEndpointConfigurator.wac = wac;
    }

    @Override
    public <T> T getEndpointInstance(Class<T> endpointClass) throws InstantiationException {
        T endPoint = wac.getAutowireCapableBeanFactory().getBean(endpointClass);
        return (endPoint != null) ? endPoint : wac.getAutowireCapableBeanFactory().createBean(endpointClass);
    }

使用参数化构造函数将其创建为@Bean。

我一定错过了使用SpringConfigurator类完成它的东西，但我不知道是什么。

Answer 1

SpringConfigurator使用ContextLoader获取弹簧上下文。 Spring Boot确实设置了ServletContext，但它从不使用ContextLoaderListener初始化ContextLoader来保存spring上下文的静态。您可以尝试添加ContextLoaderListener或作为解决方法，您可以编写自己的上下文持有者和配置程序。

以下是一个例子：

第一个上下文持有者和配置者：

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;

import javax.websocket.server.ServerEndpointConfig;

public class CustomSpringConfigurator extends ServerEndpointConfig.Configurator implements ApplicationContextAware {

    /**
     * Spring application context.
     */
    private static volatile BeanFactory context;

    @Override
    public <T> T getEndpointInstance(Class<T> clazz) throws InstantiationException {
        return context.getBean(clazz);
    }

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        CustomSpringConfigurator.context = applicationContext;
    }
}

要获取上下文，我们需要将其配置为Bean：

@ConditionalOnWebApplication
@Configuration
public class WebSocketConfigurator {

...

    @Bean
    public CustomSpringConfigurator customSpringConfigurator() {
        return new CustomSpringConfigurator(); // This is just to get context
    }
}

然后你需要正确设置配置器：

@ServerEndpoint(value = "/", decoders = MessageDecoder.class, 
encoders = MessageEncoder.class, configurator = CustomSpringConfigurator.class)
public class ServerEndPoint {
...
}

作为旁注，是的，如果您删除SpringConfigurator您的应用程序将启动，您可以处理请求。但你无法自动装配其他豆类。

Answer 2

感谢Sergi Almar和his answer，我已经设法使用Spring实现而不是javax.websocket实现：

public class SpringWebSocketHandler extends TextWebSocketHandler {

    private final Set<CommunicationObserver> observers = Sets.newConcurrentHashSet();

    @Autowired
    private MessageContext mc;

    @Override
    protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {
        Message msg = mc.parse(message.getPayload());

        for (CommunicationObserver o : observers) {
            o.packetReceived(session, msg);
        }
    }
}

配置文件：

@ConditionalOnWebApplication
@Configuration
public class WebSocketConfigurator implements WebSocketConfigurer {

    @Override
    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
        registry.addHandler(myHandler(), "/").setAllowedOrigins("*");
    }

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

请注意，setAllowedOrigins（＆＃34; *＆＃34;）对我来说是强制性的，因为在使用java客户端时，我遇到以下错误：

org.springframework.web.util.WebUtils : Failed to parse Origin header value [localhost:8080]

另请注意，MessageContext用于解析/格式化字符串而不是MessageEncoder / Decoder类（它们继承自MessageContext）。

Answer 3

使用Spring Boot时，SpringContextLoaderListener不需要SpringConfigurator.class加载Spring上下文。

这就是为什么需要端点和ServerEndpointExporter bean。

要使示例正常工作，您唯一需要做的就是从SpringConfigurator.class端点定义中删除@ServerEndPoint。

Springboot @ServerEndPoint“无法找到根WebApplicationContext。”

3 个答案: