spring SimpAttributes 源码

spring SimpAttributes 代码

文件路径：/spring-messaging/src/main/java/org/springframework/messaging/simp/SimpAttributes.java

/*
 * 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.messaging.simp;

import java.util.Map;

import org.apache.commons.logging.Log;

import org.springframework.lang.Nullable;
import org.springframework.messaging.Message;
import org.springframework.messaging.MessageHeaders;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;

/**
 * A wrapper class for access to attributes associated with a SiMP session
 * (e.g. WebSocket session).
 *
 * @author Rossen Stoyanchev
 * @since 4.1
 */
public class SimpAttributes {

	/** Key for the mutex session attribute. */
	public static final String SESSION_MUTEX_NAME = SimpAttributes.class.getName() + ".MUTEX";

	/** Key set after the session is completed. */
	public static final String SESSION_COMPLETED_NAME = SimpAttributes.class.getName() + ".COMPLETED";

	/** Prefix for the name of session attributes used to store destruction callbacks. */
	public static final String DESTRUCTION_CALLBACK_NAME_PREFIX =
			SimpAttributes.class.getName() + ".DESTRUCTION_CALLBACK.";

	private static final Log logger = SimpLogging.forLogName(SimpAttributes.class);


	private final String sessionId;

	private final Map<String, Object> attributes;


	/**
	 * Constructor wrapping the given session attributes map.
	 * @param sessionId the id of the associated session
	 * @param attributes the attributes
	 */
	public SimpAttributes(String sessionId, Map<String, Object> attributes) {
		Assert.notNull(sessionId, "'sessionId' is required");
		Assert.notNull(attributes, "'attributes' is required");
		this.sessionId = sessionId;
		this.attributes = attributes;
	}


	/**
	 * Return the value for the attribute of the given name, if any.
	 * @param name the name of the attribute
	 * @return the current attribute value, or {@code null} if not found
	 */
	@Nullable
	public Object getAttribute(String name) {
		return this.attributes.get(name);
	}

	/**
	 * Set the value with the given name replacing an existing value (if any).
	 * @param name the name of the attribute
	 * @param value the value for the attribute
	 */
	public void setAttribute(String name, Object value) {
		this.attributes.put(name, value);
	}

	/**
	 * Remove the attribute of the given name, if it exists.
	 * <p>Also removes the registered destruction callback for the specified
	 * attribute, if any. However it <i>does not</i> execute the callback.
	 * It is assumed the removed object will continue to be used and destroyed
	 * independently at the appropriate time.
	 * @param name the name of the attribute
	 */
	public void removeAttribute(String name) {
		this.attributes.remove(name);
		removeDestructionCallback(name);
	}

	/**
	 * Retrieve the names of all attributes.
	 * @return the attribute names as String array, never {@code null}
	 */
	public String[] getAttributeNames() {
		return StringUtils.toStringArray(this.attributes.keySet());
	}

	/**
	 * Register a callback to execute on destruction of the specified attribute.
	 * The callback is executed when the session is closed.
	 * @param name the name of the attribute to register the callback for
	 * @param callback the destruction callback to be executed
	 */
	public void registerDestructionCallback(String name, Runnable callback) {
		synchronized (getSessionMutex()) {
			if (isSessionCompleted()) {
				throw new IllegalStateException("Session id=" + getSessionId() + " already completed");
			}
			this.attributes.put(DESTRUCTION_CALLBACK_NAME_PREFIX + name, callback);
		}
	}

	private void removeDestructionCallback(String name) {
		synchronized (getSessionMutex()) {
			this.attributes.remove(DESTRUCTION_CALLBACK_NAME_PREFIX + name);
		}
	}

	/**
	 * Return an id for the associated session.
	 * @return the session id as String (never {@code null})
	 */
	public String getSessionId() {
		return this.sessionId;
	}

	/**
	 * Expose the object to synchronize on for the underlying session.
	 * @return the session mutex to use (never {@code null})
	 */
	public Object getSessionMutex() {
		Object mutex = this.attributes.get(SESSION_MUTEX_NAME);
		if (mutex == null) {
			mutex = this.attributes;
		}
		return mutex;
	}

	/**
	 * Whether the {@link #sessionCompleted()} was already invoked.
	 */
	public boolean isSessionCompleted() {
		return (this.attributes.get(SESSION_COMPLETED_NAME) != null);
	}

	/**
	 * Invoked when the session is completed. Executed completion callbacks.
	 */
	public void sessionCompleted() {
		synchronized (getSessionMutex()) {
			if (!isSessionCompleted()) {
				executeDestructionCallbacks();
				this.attributes.put(SESSION_COMPLETED_NAME, Boolean.TRUE);
			}
		}
	}

	private void executeDestructionCallbacks() {
		this.attributes.forEach((key, value) -> {
			if (key.startsWith(DESTRUCTION_CALLBACK_NAME_PREFIX)) {
				try {
					((Runnable) value).run();
				}
				catch (Throwable ex) {
					logger.error("Uncaught error in session attribute destruction callback", ex);
				}
			}
		});
	}


	/**
	 * Extract the SiMP session attributes from the given message and
	 * wrap them in a {@link SimpAttributes} instance.
	 * @param message the message to extract session attributes from
	 */
	public static SimpAttributes fromMessage(Message<?> message) {
		Assert.notNull(message, "Message must not be null");
		MessageHeaders headers = message.getHeaders();
		String sessionId = SimpMessageHeaderAccessor.getSessionId(headers);
		Map<String, Object> sessionAttributes = SimpMessageHeaderAccessor.getSessionAttributes(headers);
		if (sessionId == null) {
			throw new IllegalStateException("No session id in " + message);
		}
		if (sessionAttributes == null) {
			throw new IllegalStateException("No session attributes in " + message);
		}
		return new SimpAttributes(sessionId, sessionAttributes);
	}

}

相关信息

spring 源码目录

相关文章

spring SimpAttributesContextHolder 源码

spring SimpLogging 源码

spring SimpMessageHeaderAccessor 源码

spring SimpMessageMappingInfo 源码

spring SimpMessageSendingOperations 源码

spring SimpMessageType 源码

spring SimpMessageTypeMessageCondition 源码

spring SimpMessagingTemplate 源码

spring SimpSessionScope 源码

spring package-info 源码