/*
* Copyright 2002-2010 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.core.convert.support;
import java.util.Collection;
import java.util.Collections;
import java.util.Set;
import org.springframework.core.CollectionFactory;
import org.springframework.core.convert.ConversionService;
import org.springframework.core.convert.TypeDescriptor;
import org.springframework.core.convert.converter.ConditionalGenericConverter;
/**
* Converts from a Collection to another Collection.
*
* <p>First, creates a new Collection of the requested targetType with a size equal to the
* size of the source Collection. Then copies each element in the source collection to the
* target collection. Will perform an element conversion from the source collection's
* parameterized type to the target collection's parameterized type if necessary.
*
* @author Keith Donald
* @since 3.0
*/
final class CollectionToCollectionConverter implements ConditionalGenericConverter {
private final ConversionService conversionService;
public CollectionToCollectionConverter(ConversionService conversionService) {
this.conversionService = conversionService;
}
public Set<ConvertiblePair> getConvertibleTypes() {
return Collections.singleton(new ConvertiblePair(Collection.class, Collection.class));
}
public boolean matches(TypeDescriptor sourceType, TypeDescriptor targetType) {
return this.conversionService.canConvert(sourceType.getElementTypeDescriptor(), targetType.getElementTypeDescriptor());
}
@SuppressWarnings("unchecked")
public Object convert(Object source, TypeDescriptor sourceType, TypeDescriptor targetType) {
if (source == null) {
return null;
}
Collection<?> sourceCollection = (Collection<?>) source;
if (sourceCollection.isEmpty()) {
return sourceCollection;
}
Collection target = CollectionFactory.createCollection(targetType.getType(), sourceCollection.size());
for (Object sourceElement : sourceCollection) {
Object targetElement = this.conversionService.convert(sourceElement,
sourceType.getElementTypeDescriptor(sourceElement),
targetType.getElementTypeDescriptor(sourceElement));
target.add(targetElement);
}
return target;
}
}
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