org.springframework.messaging.converter.CompositeMessageConverter Maven / Gradle / Ivy
/*
* Copyright 2002-2016 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.converter;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import org.springframework.lang.Nullable;
import org.springframework.messaging.Message;
import org.springframework.messaging.MessageHeaders;
import org.springframework.util.Assert;
/**
* A {@link MessageConverter} that delegates to a list of registered converters
* to be invoked until one of them returns a non-null result.
*
* As of 4.2.1, this composite converter implements {@link SmartMessageConverter}
* in order to support the delegation of conversion hints.
*
* @author Rossen Stoyanchev
* @author Juergen Hoeller
* @since 4.0
*/
public class CompositeMessageConverter implements SmartMessageConverter {
private final List converters;
/**
* Create an instance with the given converters.
*/
public CompositeMessageConverter(Collection converters) {
Assert.notEmpty(converters, "Converters must not be empty");
this.converters = new ArrayList<>(converters);
}
@Override
@Nullable
public Object fromMessage(Message message, Class targetClass) {
for (MessageConverter converter : getConverters()) {
Object result = converter.fromMessage(message, targetClass);
if (result != null) {
return result;
}
}
return null;
}
@Override
@Nullable
public Object fromMessage(Message message, Class targetClass, @Nullable Object conversionHint) {
for (MessageConverter converter : getConverters()) {
Object result = (converter instanceof SmartMessageConverter ?
((SmartMessageConverter) converter).fromMessage(message, targetClass, conversionHint) :
converter.fromMessage(message, targetClass));
if (result != null) {
return result;
}
}
return null;
}
@Override
@Nullable
public Message toMessage(Object payload, @Nullable MessageHeaders headers) {
for (MessageConverter converter : getConverters()) {
Message result = converter.toMessage(payload, headers);
if (result != null) {
return result;
}
}
return null;
}
@Override
@Nullable
public Message toMessage(Object payload, @Nullable MessageHeaders headers, @Nullable Object conversionHint) {
for (MessageConverter converter : getConverters()) {
Message result = (converter instanceof SmartMessageConverter ?
((SmartMessageConverter) converter).toMessage(payload, headers, conversionHint) :
converter.toMessage(payload, headers));
if (result != null) {
return result;
}
}
return null;
}
/**
* Return the underlying list of delegate converters.
*/
public List getConverters() {
return this.converters;
}
@Override
public String toString() {
return "CompositeMessageConverter[converters=" + getConverters() + "]";
}
}