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;
/**
* A converter that can convert from one collection type to another.
*
* @author Keith Donald
*/
public class CollectionToCollection implements Converter {
private static final int DEFAULT_INITIAL_SIZE = 16;
private ConversionService conversionService;
private ConversionExecutor elementConverter;
/**
* Creates a new collection-to-collection converter
* @param conversionService the conversion service to use to convert collection elements to add to the target
* collection
*/
public CollectionToCollection(ConversionService conversionService) {
this.conversionService = conversionService;
}
/**
* Creates a new collection-to-collection converter
* @param elementConverter a specific converter to use to convert collection elements added to the target collection
*/
public CollectionToCollection(ConversionExecutor elementConverter) {
this.elementConverter = elementConverter;
}
public Class<?> getSourceClass() {
return Collection.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 targetCollection = CollectionFactory.createCollection(targetClass, DEFAULT_INITIAL_SIZE);
ConversionExecutor elementConverter = getElementConverter(source, (Class<? extends Collection<?>>) targetClass);
Collection sourceCollection = (Collection) source;
for (Object value : sourceCollection) {
if (elementConverter != null) {
value = elementConverter.execute(value);
}
targetCollection.add(value);
}
return targetCollection;
}
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;
}
}
}