001/*
002 * Copyright 2002-2017 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.web.socket.server.standard;
018
019import java.util.Arrays;
020import java.util.Map;
021import java.util.concurrent.ConcurrentHashMap;
022
023import javax.websocket.server.ServerEndpoint;
024import javax.websocket.server.ServerEndpointConfig.Configurator;
025
026import org.apache.commons.logging.Log;
027import org.apache.commons.logging.LogFactory;
028
029import org.springframework.core.annotation.AnnotationUtils;
030import org.springframework.lang.Nullable;
031import org.springframework.stereotype.Component;
032import org.springframework.util.ClassUtils;
033import org.springframework.util.ObjectUtils;
034import org.springframework.web.context.ContextLoader;
035import org.springframework.web.context.WebApplicationContext;
036
037/**
038 * A {@link javax.websocket.server.ServerEndpointConfig.Configurator} for initializing
039 * {@link ServerEndpoint}-annotated classes through Spring.
040 *
041 * <p>
042 * <pre class="code">
043 * &#064;ServerEndpoint(value = "/echo", configurator = SpringConfigurator.class)
044 * public class EchoEndpoint {
045 *     // ...
046 * }
047 * </pre>
048 *
049 * @author Rossen Stoyanchev
050 * @since 4.0
051 * @see ServerEndpointExporter
052 */
053public class SpringConfigurator extends Configurator {
054
055        private static final String NO_VALUE = ObjectUtils.identityToString(new Object());
056
057        private static final Log logger = LogFactory.getLog(SpringConfigurator.class);
058
059        private static final Map<String, Map<Class<?>, String>> cache =
060                        new ConcurrentHashMap<>();
061
062
063        @SuppressWarnings("unchecked")
064        @Override
065        public <T> T getEndpointInstance(Class<T> endpointClass) throws InstantiationException {
066                WebApplicationContext wac = ContextLoader.getCurrentWebApplicationContext();
067                if (wac == null) {
068                        String message = "Failed to find the root WebApplicationContext. Was ContextLoaderListener not used?";
069                        logger.error(message);
070                        throw new IllegalStateException(message);
071                }
072
073                String beanName = ClassUtils.getShortNameAsProperty(endpointClass);
074                if (wac.containsBean(beanName)) {
075                        T endpoint = wac.getBean(beanName, endpointClass);
076                        if (logger.isTraceEnabled()) {
077                                logger.trace("Using @ServerEndpoint singleton " + endpoint);
078                        }
079                        return endpoint;
080                }
081
082                Component ann = AnnotationUtils.findAnnotation(endpointClass, Component.class);
083                if (ann != null && wac.containsBean(ann.value())) {
084                        T endpoint = wac.getBean(ann.value(), endpointClass);
085                        if (logger.isTraceEnabled()) {
086                                logger.trace("Using @ServerEndpoint singleton " + endpoint);
087                        }
088                        return endpoint;
089                }
090
091                beanName = getBeanNameByType(wac, endpointClass);
092                if (beanName != null) {
093                        return (T) wac.getBean(beanName);
094                }
095
096                if (logger.isTraceEnabled()) {
097                        logger.trace("Creating new @ServerEndpoint instance of type " + endpointClass);
098                }
099                return wac.getAutowireCapableBeanFactory().createBean(endpointClass);
100        }
101
102        @Nullable
103        private String getBeanNameByType(WebApplicationContext wac, Class<?> endpointClass) {
104                String wacId = wac.getId();
105
106                Map<Class<?>, String> beanNamesByType = cache.get(wacId);
107                if (beanNamesByType == null) {
108                        beanNamesByType = new ConcurrentHashMap<>();
109                        cache.put(wacId, beanNamesByType);
110                }
111
112                if (!beanNamesByType.containsKey(endpointClass)) {
113                        String[] names = wac.getBeanNamesForType(endpointClass);
114                        if (names.length == 1) {
115                                beanNamesByType.put(endpointClass, names[0]);
116                        }
117                        else {
118                                beanNamesByType.put(endpointClass, NO_VALUE);
119                                if (names.length > 1) {
120                                        throw new IllegalStateException("Found multiple @ServerEndpoint's of type [" +
121                                                        endpointClass.getName() + "]: bean names " + Arrays.asList(names));
122                                }
123                        }
124                }
125
126                String beanName = beanNamesByType.get(endpointClass);
127                return (NO_VALUE.equals(beanName) ? null : beanName);
128        }
129
130}