/*
* Copyright 2004-2012 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.binding.convert.converters;
import java.util.Collection;
import org.springframework.binding.convert.ConversionExecutor;
import org.springframework.binding.convert.ConversionService;
import org.springframework.core.CollectionFactory;
import org.springframework.core.GenericCollectionTypeResolver;
/**
* Special two-way converter that converts an object to an single-element collection. Supports type conversion of the
* individual element with parameterized collection implementations.
*
* @author Keith Donald
*/
public class ObjectToCollection implements Converter {
private static final int DEFAULT_INITIAL_CAPACITY = 16;
private ConversionService conversionService;
private ConversionExecutor elementConverter;
/**
* Creates a new object to collection converter
* @param conversionService the conversion service to lookup the converter to use to convert an object when adding
* it to a target collection
*/
public ObjectToCollection(ConversionService conversionService) {
this.conversionService = conversionService;
}
/**
* Creates a new object to collection converter
* @param elementConverter a specific converter to execute on an object when adding it to a target collection
*/
public ObjectToCollection(ConversionExecutor elementConverter) {
this.elementConverter = elementConverter;
}
public Class<?> getSourceClass() {
return Object.class;
}
public Class<?> getTargetClass() {
return Collection.class;
}
@SuppressWarnings({ "rawtypes", "unchecked" })
public Object convertSourceToTargetClass(Object source, Class<?> targetClass) throws Exception {
if (source == null) {
return null;
}
Collection collection = CollectionFactory.createCollection(targetClass, DEFAULT_INITIAL_CAPACITY);
ConversionExecutor converter = getElementConverter(source, (Class<? extends Collection<?>>) targetClass);
Object value;
if (converter != null) {
value = converter.execute(source);
} else {
value = source;
}
collection.add(value);
return collection;
}
private ConversionExecutor getElementConverter(Object source, Class<? extends Collection<?>> targetClass) {
if (elementConverter != null) {
return elementConverter;
} else {
Class<?> elementType = GenericCollectionTypeResolver.getCollectionType(targetClass);
if (elementType != null) {
Class<?> componentType = source.getClass().getComponentType();
return conversionService.getConversionExecutor(componentType, elementType);
}
return null;
}
}
}