/*
* 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.messaging;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.UUID;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.util.AlternativeJdkIdGenerator;
import org.springframework.util.IdGenerator;
/**
* The headers for a {@link Message}
*
* IMPORTANT: This class is immutable. Any mutating operation such as
* {@code put(..)}, {@code putAll(..)} and others will throw
* {@link UnsupportedOperationException}.
*
Subclasses do have access to the raw headers, however, via {@link #getRawHeaders()}.
*
* One way to create message headers is to use the
* {@link org.springframework.messaging.support.MessageBuilder MessageBuilder}:
*
* A second option is to create {@link org.springframework.messaging.support.GenericMessage}
* passing a payload as {@link Object} and headers as a {@link Map java.util.Map}:
*
* Map headers = new HashMap();
* headers.put("key1", "value1");
* headers.put("key2", "value2");
* new GenericMessage("foo", headers);
*
* A third option is to use {@link org.springframework.messaging.support.MessageHeaderAccessor}
* or one of its sub-classes to create specific categories of headers.
*
* @author Arjen Poutsma
* @author Mark Fisher
* @author Gary Russell
* @since 4.0
* @see org.springframework.messaging.support.MessageBuilder
* @see org.springframework.messaging.support.MessageHeaderAccessor
*/
public class MessageHeaders implements Map, Serializable {
private static final long serialVersionUID = -4615750558355702881L;
private static final Log logger = LogFactory.getLog(MessageHeaders.class);
private static volatile IdGenerator idGenerator = null;
private static final IdGenerator defaultIdGenerator = new AlternativeJdkIdGenerator();
/**
* The key for the Message ID. This is an automatically generated UUID and
* should never be explicitly set in the header map except in the
* case of Message deserialization where the serialized Message's generated
* UUID is being restored.
*/
public static final String ID = "id";
public static final String TIMESTAMP = "timestamp";
public static final String REPLY_CHANNEL = "replyChannel";
public static final String ERROR_CHANNEL = "errorChannel";
public static final String CONTENT_TYPE = "contentType";
private final Map headers;
/**
* Constructs a minimal {@link MessageHeaders} with zero headers.
*/
protected MessageHeaders() {
this.headers = new HashMap();
}
/**
* Consructs a {@link MessageHeaders} from the headers map; adding (or
* overwriting) the {@link #ID} and {@link #TIMESTAMP} headers.
* @param headers The map.
*/
public MessageHeaders(Map headers) {
this.headers = (headers != null) ? new HashMap(headers) : new HashMap();
this.headers.put(ID, ((idGenerator != null) ? idGenerator : defaultIdGenerator).generateId());
this.headers.put(TIMESTAMP, System.currentTimeMillis());
}
protected Map getRawHeaders() {
return this.headers;
}
public UUID getId() {
return this.get(ID, UUID.class);
}
public Long getTimestamp() {
return this.get(TIMESTAMP, Long.class);
}
public Object getReplyChannel() {
return this.get(REPLY_CHANNEL);
}
public Object getErrorChannel() {
return this.get(ERROR_CHANNEL);
}
@SuppressWarnings("unchecked")
public T get(Object key, Class type) {
Object value = this.headers.get(key);
if (value == null) {
return null;
}
if (!type.isAssignableFrom(value.getClass())) {
throw new IllegalArgumentException("Incorrect type specified for header '" +
key + "'. Expected [" + type + "] but actual type is [" + value.getClass() + "]");
}
return (T) value;
}
@Override
public int hashCode() {
return this.headers.hashCode();
}
@Override
public boolean equals(Object object) {
if (this == object) {
return true;
}
if (object != null && object instanceof MessageHeaders) {
MessageHeaders other = (MessageHeaders) object;
return this.headers.equals(other.headers);
}
return false;
}
@Override
public String toString() {
Map map = new LinkedHashMap(this.headers);
map.put(ID, map.remove(ID)); // remove and add again at the end
map.put(TIMESTAMP, map.remove(TIMESTAMP));
return map.toString();
}
/*
* Map implementation
*/
public boolean containsKey(Object key) {
return this.headers.containsKey(key);
}
public boolean containsValue(Object value) {
return this.headers.containsValue(value);
}
public Set> entrySet() {
return Collections.unmodifiableSet(this.headers.entrySet());
}
public Object get(Object key) {
return this.headers.get(key);
}
public boolean isEmpty() {
return this.headers.isEmpty();
}
public Set keySet() {
return Collections.unmodifiableSet(this.headers.keySet());
}
public int size() {
return this.headers.size();
}
public Collection