Java tutorial
/* * Copyright 2002-2018 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 * * https://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.util.Arrays; import java.util.LinkedHashSet; import java.util.List; import java.util.Map; import java.util.Set; import javax.servlet.ServletContext; import javax.websocket.DeploymentException; import javax.websocket.server.ServerContainer; import javax.websocket.server.ServerEndpoint; import javax.websocket.server.ServerEndpointConfig; import org.springframework.beans.factory.InitializingBean; import org.springframework.beans.factory.SmartInitializingSingleton; import org.springframework.context.ApplicationContext; import org.springframework.lang.Nullable; import org.springframework.util.Assert; import org.springframework.web.context.support.WebApplicationObjectSupport; /** * 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 {@code web.xml}. * * @author Rossen Stoyanchev * @author Juergen Hoeller * @since 4.0 * @see ServerEndpointRegistration * @see SpringConfigurator * @see ServletServerContainerFactoryBean */ public class ServerEndpointExporter extends WebApplicationObjectSupport implements InitializingBean, SmartInitializingSingleton { @Nullable private List<Class<?>> annotatedEndpointClasses; @Nullable 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 = Arrays.asList(annotatedEndpointClasses); } /** * Set the JSR-356 {@link ServerContainer} to use for endpoint registration. * If not set, the container is going to be retrieved via the {@code ServletContext}. */ public void setServerContainer(@Nullable ServerContainer serverContainer) { this.serverContainer = serverContainer; } /** * Return the JSR-356 {@link ServerContainer} to use for endpoint registration. */ @Nullable protected ServerContainer getServerContainer() { return this.serverContainer; } @Override protected void initServletContext(ServletContext servletContext) { if (this.serverContainer == null) { this.serverContainer = (ServerContainer) servletContext .getAttribute("javax.websocket.server.ServerContainer"); } } @Override protected boolean isContextRequired() { return false; } @Override public void afterPropertiesSet() { Assert.state(getServerContainer() != null, "javax.websocket.server.ServerContainer not available"); } @Override public void afterSingletonsInstantiated() { registerEndpoints(); } /** * Actually register the endpoints. Called by {@link #afterSingletonsInstantiated()}. */ protected void registerEndpoints() { Set<Class<?>> endpointClasses = new LinkedHashSet<>(); if (this.annotatedEndpointClasses != null) { endpointClasses.addAll(this.annotatedEndpointClasses); } ApplicationContext context = getApplicationContext(); if (context != null) { String[] endpointBeanNames = context.getBeanNamesForAnnotation(ServerEndpoint.class); for (String beanName : endpointBeanNames) { endpointClasses.add(context.getType(beanName)); } } for (Class<?> endpointClass : endpointClasses) { registerEndpoint(endpointClass); } if (context != null) { Map<String, ServerEndpointConfig> endpointConfigMap = context .getBeansOfType(ServerEndpointConfig.class); for (ServerEndpointConfig endpointConfig : endpointConfigMap.values()) { registerEndpoint(endpointConfig); } } } private void registerEndpoint(Class<?> endpointClass) { ServerContainer serverContainer = getServerContainer(); Assert.state(serverContainer != null, "No ServerContainer set. Most likely the server's own WebSocket ServletContainerInitializer " + "has not run yet. Was the Spring ApplicationContext refreshed through a " + "org.springframework.web.context.ContextLoaderListener, " + "i.e. after the ServletContext has been fully initialized?"); try { if (logger.isDebugEnabled()) { logger.debug("Registering @ServerEndpoint class: " + endpointClass); } serverContainer.addEndpoint(endpointClass); } catch (DeploymentException ex) { throw new IllegalStateException("Failed to register @ServerEndpoint class: " + endpointClass, ex); } } private void registerEndpoint(ServerEndpointConfig endpointConfig) { ServerContainer serverContainer = getServerContainer(); Assert.state(serverContainer != null, "No ServerContainer set"); try { if (logger.isDebugEnabled()) { logger.debug("Registering ServerEndpointConfig: " + endpointConfig); } serverContainer.addEndpoint(endpointConfig); } catch (DeploymentException ex) { throw new IllegalStateException("Failed to register ServerEndpointConfig: " + endpointConfig, ex); } } }