/*
* 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.simp.annotation.support;
import java.lang.annotation.Annotation;
import java.security.Principal;
import org.springframework.core.MethodParameter;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.messaging.Message;
import org.springframework.messaging.MessageChannel;
import org.springframework.messaging.MessageHeaders;
import org.springframework.messaging.handler.DestinationPatternsMessageCondition;
import org.springframework.messaging.handler.annotation.SendTo;
import org.springframework.messaging.handler.invocation.HandlerMethodReturnValueHandler;
import org.springframework.messaging.simp.SimpMessageHeaderAccessor;
import org.springframework.messaging.simp.SimpMessageSendingOperations;
import org.springframework.messaging.simp.SimpMessageType;
import org.springframework.messaging.simp.annotation.SendToUser;
import org.springframework.messaging.simp.user.DestinationUserNameProvider;
import org.springframework.messaging.support.MessageHeaderInitializer;
import org.springframework.util.Assert;
import org.springframework.util.ObjectUtils;
/**
* A {@link HandlerMethodReturnValueHandler} for sending to destinations specified in a
* {@link SendTo} or {@link SendToUser} method-level annotations.
*
* <p>The value returned from the method is converted, and turned to a {@link Message} and
* sent through the provided {@link MessageChannel}. The
* message is then enriched with the sessionId of the input message as well as the
* destination from the annotation(s). If multiple destinations are specified, a copy of
* the message is sent to each destination.
*
* @author Rossen Stoyanchev
* @since 4.0
*/
public class SendToMethodReturnValueHandler implements HandlerMethodReturnValueHandler {
private final SimpMessageSendingOperations messagingTemplate;
private final boolean annotationRequired;
private String defaultDestinationPrefix = "/topic";
private String defaultUserDestinationPrefix = "/queue";
private MessageHeaderInitializer headerInitializer;
public SendToMethodReturnValueHandler(SimpMessageSendingOperations messagingTemplate, boolean annotationRequired) {
Assert.notNull(messagingTemplate, "messagingTemplate must not be null");
this.messagingTemplate = messagingTemplate;
this.annotationRequired = annotationRequired;
}
/**
* Configure a default prefix to add to message destinations in cases where a method
* is not annotated with {@link SendTo @SendTo} or does not specify any destinations
* through the annotation's value attribute.
* <p>By default, the prefix is set to "/topic".
*/
public void setDefaultDestinationPrefix(String defaultDestinationPrefix) {
this.defaultDestinationPrefix = defaultDestinationPrefix;
}
/**
* Return the configured default destination prefix.
* @see #setDefaultDestinationPrefix(String)
*/
public String getDefaultDestinationPrefix() {
return this.defaultDestinationPrefix;
}
/**
* Configure a default prefix to add to message destinations in cases where a
* method is annotated with {@link SendToUser @SendToUser} but does not specify
* any destinations through the annotation's value attribute.
* <p>By default, the prefix is set to "/queue".
*/
public void setDefaultUserDestinationPrefix(String prefix) {
this.defaultUserDestinationPrefix = prefix;
}
/**
* Return the configured default user destination prefix.
* @see #setDefaultUserDestinationPrefix(String)
*/
public String getDefaultUserDestinationPrefix() {
return this.defaultUserDestinationPrefix;
}
/**
* Configure a {@link MessageHeaderInitializer} to apply to the headers of all
* messages sent to the client outbound channel.
*
* <p>By default this property is not set.
*/
public void setHeaderInitializer(MessageHeaderInitializer headerInitializer) {
this.headerInitializer = headerInitializer;
}
/**
* @return the configured header initializer.
*/
public MessageHeaderInitializer getHeaderInitializer() {
return this.headerInitializer;
}
@Override
public boolean supportsReturnType(MethodParameter returnType) {
if ((returnType.getMethodAnnotation(SendTo.class) != null) ||
(returnType.getMethodAnnotation(SendToUser.class) != null)) {
return true;
}
return (!this.annotationRequired);
}
@Override
public void handleReturnValue(Object returnValue, MethodParameter returnType, Message<?> message) throws Exception {
if (returnValue == null) {
return;
}
MessageHeaders headers = message.getHeaders();
String sessionId = SimpMessageHeaderAccessor.getSessionId(headers);
SendToUser sendToUser = returnType.getMethodAnnotation(SendToUser.class);
if (sendToUser != null) {
boolean broadcast = sendToUser.broadcast();
String user = getUserName(message, headers);
if (user == null) {
if (sessionId == null) {
throw new MissingSessionUserException(message);
}
user = sessionId;
broadcast = false;
}
String[] destinations = getTargetDestinations(sendToUser, message, this.defaultUserDestinationPrefix);
for (String destination : destinations) {
if (broadcast) {
this.messagingTemplate.convertAndSendToUser(user, destination, returnValue);
}
else {
this.messagingTemplate.convertAndSendToUser(user, destination, returnValue, createHeaders(sessionId));
}
}
}
else {
SendTo sendTo = returnType.getMethodAnnotation(SendTo.class);
String[] destinations = getTargetDestinations(sendTo, message, this.defaultDestinationPrefix);
for (String destination : destinations) {
this.messagingTemplate.convertAndSend(destination, returnValue, createHeaders(sessionId));
}
}
}
protected String getUserName(Message<?> message, MessageHeaders headers) {
Principal principal = SimpMessageHeaderAccessor.getUser(headers);
if (principal != null) {
return (principal instanceof DestinationUserNameProvider ?
((DestinationUserNameProvider) principal).getDestinationUserName() : principal.getName());
}
return null;
}
protected String[] getTargetDestinations(Annotation annotation, Message<?> message, String defaultPrefix) {
if (annotation != null) {
String[] value = (String[]) AnnotationUtils.getValue(annotation);
if (!ObjectUtils.isEmpty(value)) {
return value;
}
}
String name = DestinationPatternsMessageCondition.LOOKUP_DESTINATION_HEADER;
String destination = (String) message.getHeaders().get(name);
Assert.hasText(destination, "No lookup destination header in " + message);
return (destination.startsWith("/") ?
new String[] {defaultPrefix + destination} : new String[] {defaultPrefix + "/" + destination});
}
private MessageHeaders createHeaders(String sessionId) {
SimpMessageHeaderAccessor headerAccessor = SimpMessageHeaderAccessor.create(SimpMessageType.MESSAGE);
if (getHeaderInitializer() != null) {
getHeaderInitializer().initHeaders(headerAccessor);
}
headerAccessor.setSessionId(sessionId);
headerAccessor.setLeaveMutable(true);
return headerAccessor.getMessageHeaders();
}
@Override
public String toString() {
return "SendToMethodReturnValueHandler [annotationRequired=" + annotationRequired + "]";
}
}