Java tutorial
/* * Copyright 2002-2014 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.springframework.web.socket.server.standard; import java.lang.reflect.Method; import java.util.ArrayList; import java.util.Arrays; import java.util.List; import java.util.Map; import javax.websocket.DeploymentException; import javax.websocket.server.ServerContainer; import javax.websocket.server.ServerEndpoint; import javax.websocket.server.ServerEndpointConfig; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.springframework.beans.BeansException; import org.springframework.beans.factory.InitializingBean; import org.springframework.beans.factory.config.BeanPostProcessor; import org.springframework.context.ApplicationContext; import org.springframework.context.ApplicationContextAware; import org.springframework.util.Assert; import org.springframework.util.ClassUtils; import org.springframework.util.ReflectionUtils; /** * Detects beans of type {@link javax.websocket.server.ServerEndpointConfig} and registers * with the standard Java WebSocket runtime. Also detects beans annotated with * {@link ServerEndpoint} and registers them as well. Although not required, it is likely * annotated endpoints should have their {@code configurator} property set to * {@link SpringConfigurator}. * * <p>When this class is used, by declaring it in Spring configuration, it should be * possible to turn off a Servlet container's scan for WebSocket endpoints. This can be * done with the help of the {@code <absolute-ordering>} element in web.xml. * * @author Rossen Stoyanchev * @since 4.0 * @see ServerEndpointRegistration * @see SpringConfigurator * @see ServletServerContainerFactoryBean */ public class ServerEndpointExporter implements InitializingBean, BeanPostProcessor, ApplicationContextAware { private static final Log logger = LogFactory.getLog(ServerEndpointExporter.class); private final List<Class<?>> annotatedEndpointClasses = new ArrayList<Class<?>>(); private final List<Class<?>> annotatedEndpointBeanTypes = new ArrayList<Class<?>>(); private ApplicationContext applicationContext; private ServerContainer serverContainer; /** * Explicitly list annotated endpoint types that should be registered on startup. This * can be done if you wish to turn off a Servlet container's scan for endpoints, which * goes through all 3rd party jars in the, and rely on Spring configuration instead. * @param annotatedEndpointClasses {@link ServerEndpoint}-annotated types */ public void setAnnotatedEndpointClasses(Class<?>... annotatedEndpointClasses) { this.annotatedEndpointClasses.clear(); this.annotatedEndpointClasses.addAll(Arrays.asList(annotatedEndpointClasses)); } @Override public void setApplicationContext(ApplicationContext applicationContext) { this.applicationContext = applicationContext; this.serverContainer = getServerContainer(); Map<String, Object> beans = applicationContext.getBeansWithAnnotation(ServerEndpoint.class); for (String beanName : beans.keySet()) { Class<?> beanType = applicationContext.getType(beanName); if (logger.isInfoEnabled()) { logger.info( "Detected @ServerEndpoint bean '" + beanName + "', registering it as an endpoint by type"); } this.annotatedEndpointBeanTypes.add(beanType); } } protected ServerContainer getServerContainer() { Class<?> servletContextClass; try { servletContextClass = ClassUtils.forName("javax.servlet.ServletContext", getClass().getClassLoader()); } catch (Throwable ex) { return null; } try { Method getter = ReflectionUtils.findMethod(this.applicationContext.getClass(), "getServletContext"); Object servletContext = getter.invoke(this.applicationContext); Method attrMethod = ReflectionUtils.findMethod(servletContextClass, "getAttribute", String.class); return (ServerContainer) attrMethod.invoke(servletContext, "javax.websocket.server.ServerContainer"); } catch (Exception ex) { throw new IllegalStateException( "Failed to get javax.websocket.server.ServerContainer via ServletContext attribute", ex); } } @Override public void afterPropertiesSet() throws Exception { Assert.state(this.serverContainer != null, "javax.websocket.server.ServerContainer not available"); List<Class<?>> allClasses = new ArrayList<Class<?>>(this.annotatedEndpointClasses); allClasses.addAll(this.annotatedEndpointBeanTypes); for (Class<?> clazz : allClasses) { try { logger.info("Registering @ServerEndpoint type " + clazz); this.serverContainer.addEndpoint(clazz); } catch (DeploymentException e) { throw new IllegalStateException("Failed to register @ServerEndpoint type " + clazz, e); } } } @Override public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException { if (bean instanceof ServerEndpointConfig) { ServerEndpointConfig sec = (ServerEndpointConfig) bean; try { if (logger.isInfoEnabled()) { logger.info("Registering bean '" + beanName + "' as javax.websocket.Endpoint under path " + sec.getPath()); } getServerContainer().addEndpoint(sec); } catch (DeploymentException e) { throw new IllegalStateException("Failed to deploy Endpoint bean " + bean, e); } } return bean; } @Override public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException { return bean; } }