org.springframework.web.socket.server.standard.SpringConfigurator.java Source code

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Here is the source code for org.springframework.web.socket.server.standard.SpringConfigurator.java

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/*
 * Copyright 2002-2017 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.util.Arrays;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import javax.websocket.server.ServerEndpoint;
import javax.websocket.server.ServerEndpointConfig.Configurator;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.lang.Nullable;
import org.springframework.stereotype.Component;
import org.springframework.util.ClassUtils;
import org.springframework.util.ObjectUtils;
import org.springframework.web.context.ContextLoader;
import org.springframework.web.context.WebApplicationContext;

/**
 * A {@link javax.websocket.server.ServerEndpointConfig.Configurator} for initializing
 * {@link ServerEndpoint}-annotated classes through Spring.
 *
 * <p>
 * <pre class="code">
 * &#064;ServerEndpoint(value = "/echo", configurator = SpringConfigurator.class)
 * public class EchoEndpoint {
 *     // ...
 * }
 * </pre>
 *
 * @author Rossen Stoyanchev
 * @since 4.0
 * @see ServerEndpointExporter
 */
public class SpringConfigurator extends Configurator {

    private static final String NO_VALUE = ObjectUtils.identityToString(new Object());

    private static final Log logger = LogFactory.getLog(SpringConfigurator.class);

    private static final Map<String, Map<Class<?>, String>> cache = new ConcurrentHashMap<>();

    @SuppressWarnings("unchecked")
    @Override
    public <T> T getEndpointInstance(Class<T> endpointClass) throws InstantiationException {
        WebApplicationContext wac = ContextLoader.getCurrentWebApplicationContext();
        if (wac == null) {
            String message = "Failed to find the root WebApplicationContext. Was ContextLoaderListener not used?";
            logger.error(message);
            throw new IllegalStateException(message);
        }

        String beanName = ClassUtils.getShortNameAsProperty(endpointClass);
        if (wac.containsBean(beanName)) {
            T endpoint = wac.getBean(beanName, endpointClass);
            if (logger.isTraceEnabled()) {
                logger.trace("Using @ServerEndpoint singleton " + endpoint);
            }
            return endpoint;
        }

        Component ann = AnnotationUtils.findAnnotation(endpointClass, Component.class);
        if (ann != null && wac.containsBean(ann.value())) {
            T endpoint = wac.getBean(ann.value(), endpointClass);
            if (logger.isTraceEnabled()) {
                logger.trace("Using @ServerEndpoint singleton " + endpoint);
            }
            return endpoint;
        }

        beanName = getBeanNameByType(wac, endpointClass);
        if (beanName != null) {
            return (T) wac.getBean(beanName);
        }

        if (logger.isTraceEnabled()) {
            logger.trace("Creating new @ServerEndpoint instance of type " + endpointClass);
        }
        return wac.getAutowireCapableBeanFactory().createBean(endpointClass);
    }

    @Nullable
    private String getBeanNameByType(WebApplicationContext wac, Class<?> endpointClass) {
        String wacId = wac.getId();

        Map<Class<?>, String> beanNamesByType = cache.get(wacId);
        if (beanNamesByType == null) {
            beanNamesByType = new ConcurrentHashMap<>();
            cache.put(wacId, beanNamesByType);
        }

        if (!beanNamesByType.containsKey(endpointClass)) {
            String[] names = wac.getBeanNamesForType(endpointClass);
            if (names.length == 1) {
                beanNamesByType.put(endpointClass, names[0]);
            } else {
                beanNamesByType.put(endpointClass, NO_VALUE);
                if (names.length > 1) {
                    throw new IllegalStateException("Found multiple @ServerEndpoint's of type ["
                            + endpointClass.getName() + "]: bean names " + Arrays.asList(names));
                }
            }
        }

        String beanName = beanNamesByType.get(endpointClass);
        return (NO_VALUE.equals(beanName) ? null : beanName);
    }

}