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CollectionToCollectionConverter avoids collection copy for untyped collection when simply returning source anyway

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Also uses addAll instead of iteration over untyped collection now, supporting optimized addAll in target collection type, and avoids repeated getElementTypeDescriptor calls.

Issue: SPR-11479
This commit is contained in:
Juergen Hoeller
2014-03-10 15:59:19 +01:00
parent 40b81fcc3e
commit bea94d5302
2 changed files with 79 additions and 55 deletions
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26
spring-core/src/main/java/org/springframework/core/convert/support/CollectionToCollectionConverter.java
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@@ -1,5 +1,5 @@
/*
* Copyright 2002-2012 the original author or authors.
* 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.
@@ -34,16 +34,19 @@ import org.springframework.core.convert.converter.ConditionalGenericConverter;
* parameterized type to the target collection's parameterized type if necessary.
*
* @author Keith Donald
* @author Juergen Hoeller
* @since 3.0
*/
final class CollectionToCollectionConverter implements ConditionalGenericConverter {
private final ConversionService conversionService;
public CollectionToCollectionConverter(ConversionService conversionService) {
this.conversionService = conversionService;
}
@Override
public Set<ConvertiblePair> getConvertibleTypes() {
return Collections.singleton(new ConvertiblePair(Collection.class, Collection.class));
@@ -60,27 +63,34 @@ final class CollectionToCollectionConverter implements ConditionalGenericConvert
if (source == null) {
return null;
}
boolean copyRequired = !targetType.getType().isInstance(source);
Collection<?> sourceCollection = (Collection<?>) source;
// Shortcut if possible...
boolean copyRequired = !targetType.getType().isInstance(source);
if (!copyRequired && sourceCollection.isEmpty()) {
return sourceCollection;
return source;
}
TypeDescriptor elementDesc = targetType.getElementTypeDescriptor();
if (elementDesc == null && !copyRequired) {
return source;
}
// At this point, we need a collection copy in any case, even if just for finding out about element copies...
Collection<Object> target = CollectionFactory.createCollection(targetType.getType(), sourceCollection.size());
if (targetType.getElementTypeDescriptor() == null) {
for (Object element : sourceCollection) {
target.add(element);
}
if (elementDesc == null) {
target.addAll(sourceCollection);
}
else {
for (Object sourceElement : sourceCollection) {
Object targetElement = this.conversionService.convert(sourceElement,
sourceType.elementTypeDescriptor(sourceElement), targetType.getElementTypeDescriptor());
sourceType.elementTypeDescriptor(sourceElement), elementDesc);
target.add(targetElement);
if (sourceElement != targetElement) {
copyRequired = true;
}
}
}
return (copyRequired ? target : source);
}