/*
* Copyright 2002-2015 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.core;
import java.util.Map;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.messaging.Message;
import org.springframework.messaging.MessageHeaders;
import org.springframework.messaging.MessagingException;
import org.springframework.messaging.converter.MessageConversionException;
import org.springframework.messaging.converter.MessageConverter;
import org.springframework.messaging.converter.SimpleMessageConverter;
import org.springframework.messaging.converter.SmartMessageConverter;
import org.springframework.util.Assert;
/**
* Abstract base class for implementations of {@link MessageSendingOperations}.
*
* @author Mark Fisher
* @author Rossen Stoyanchev
* @author Stephane Nicoll
* @since 4.0
*/
public abstract class AbstractMessageSendingTemplate<D> implements MessageSendingOperations<D> {
/**
* Name of the header that can be set to provide further information
* (e.g. a {@code MethodParameter} instance) about the origin of the
* payload, to be taken into account as a conversion hint.
* @since 4.2
*/
public static final String CONVERSION_HINT_HEADER = "conversionHint";
protected final Log logger = LogFactory.getLog(getClass());
private volatile D defaultDestination;
private volatile MessageConverter converter = new SimpleMessageConverter();
/**
* Configure the default destination to use in send methods that don't have
* a destination argument. If a default destination is not configured, send methods
* without a destination argument will raise an exception if invoked.
*/
public void setDefaultDestination(D defaultDestination) {
this.defaultDestination = defaultDestination;
}
/**
* Return the configured default destination.
*/
public D getDefaultDestination() {
return this.defaultDestination;
}
/**
* Set the {@link MessageConverter} to use in {@code convertAndSend} methods.
* <p>By default, {@link SimpleMessageConverter} is used.
* @param messageConverter the message converter to use
*/
public void setMessageConverter(MessageConverter messageConverter) {
Assert.notNull(messageConverter, "'messageConverter' must not be null");
this.converter = messageConverter;
}
/**
* Return the configured {@link MessageConverter}.
*/
public MessageConverter getMessageConverter() {
return this.converter;
}
@Override
public void send(Message<?> message) {
send(getRequiredDefaultDestination(), message);
}
protected final D getRequiredDefaultDestination() {
Assert.state(this.defaultDestination != null, "No 'defaultDestination' configured");
return this.defaultDestination;
}
@Override
public void send(D destination, Message<?> message) {
doSend(destination, message);
}
protected abstract void doSend(D destination, Message<?> message);
@Override
public void convertAndSend(Object payload) throws MessagingException {
convertAndSend(payload, null);
}
@Override
public void convertAndSend(D destination, Object payload) throws MessagingException {
convertAndSend(destination, payload, (Map<String, Object>) null);
}
@Override
public void convertAndSend(D destination, Object payload, Map<String, Object> headers) throws MessagingException {
convertAndSend(destination, payload, headers, null);
}
@Override
public void convertAndSend(Object payload, MessagePostProcessor postProcessor) throws MessagingException {
convertAndSend(getRequiredDefaultDestination(), payload, postProcessor);
}
@Override
public void convertAndSend(D destination, Object payload, MessagePostProcessor postProcessor)
throws MessagingException {
convertAndSend(destination, payload, null, postProcessor);
}
@Override
public void convertAndSend(D destination, Object payload, Map<String, Object> headers,
MessagePostProcessor postProcessor) throws MessagingException {
Message<?> message = doConvert(payload, headers, postProcessor);
send(destination, message);
}
/**
* Convert the given Object to serialized form, possibly using a
* {@link MessageConverter}, wrap it as a message with the given
* headers and apply the given post processor.
* @param payload the Object to use as payload
* @param headers headers for the message to send
* @param postProcessor the post processor to apply to the message
* @return the converted message
*/
protected Message<?> doConvert(Object payload, Map<String, Object> headers, MessagePostProcessor postProcessor) {
MessageHeaders messageHeaders = null;
Object conversionHint = (headers != null ? headers.get(CONVERSION_HINT_HEADER) : null);
Map<String, Object> headersToUse = processHeadersToSend(headers);
if (headersToUse != null) {
if (headersToUse instanceof MessageHeaders) {
messageHeaders = (MessageHeaders) headersToUse;
}
else {
messageHeaders = new MessageHeaders(headersToUse);
}
}
MessageConverter converter = getMessageConverter();
Message<?> message = (converter instanceof SmartMessageConverter ?
((SmartMessageConverter) converter).toMessage(payload, messageHeaders, conversionHint) :
converter.toMessage(payload, messageHeaders));
if (message == null) {
String payloadType = (payload != null ? payload.getClass().getName() : null);
Object contentType = (messageHeaders != null ? messageHeaders.get(MessageHeaders.CONTENT_TYPE) : null);
throw new MessageConversionException("Unable to convert payload with type='" + payloadType +
"', contentType='" + contentType + "', converter=[" + getMessageConverter() + "]");
}
if (postProcessor != null) {
message = postProcessor.postProcessMessage(message);
}
return message;
}
/**
* Provides access to the map of input headers before a send operation.
* Subclasses can modify the headers and then return the same or a different map.
* <p>This default implementation in this class returns the input map.
* @param headers the headers to send (or {@code null} if none)
* @return the actual headers to send (or {@code null} if none)
*/
protected Map<String, Object> processHeadersToSend(Map<String, Object> headers) {
return headers;
}
}