/*
* 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.Collections;
import java.util.Map;
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 a Map to another Map.
*
* <p>First, creates a new Map of the requested targetType with a size equal to the
* size of the source Map. Then copies each element in the source map to the target map.
* Will perform a conversion from the source maps's parameterized K,V types to the target
* map's parameterized types K,V if necessary.
*
* @author Keith Donald
* @since 3.0
*/
final class MapToMapConverter implements ConditionalGenericConverter {
private final ConversionService conversionService;
public MapToMapConverter(ConversionService conversionService) {
this.conversionService = conversionService;
}
public Set<ConvertiblePair> getConvertibleTypes() {
return Collections.singleton(new ConvertiblePair(Map.class, Map.class));
}
public boolean matches(TypeDescriptor sourceType, TypeDescriptor targetType) {
return this.conversionService.canConvert(sourceType.getMapKeyTypeDescriptor(), targetType.getMapKeyTypeDescriptor()) &&
this.conversionService.canConvert(sourceType.getMapValueTypeDescriptor(), targetType.getMapValueTypeDescriptor());
}
@SuppressWarnings("unchecked")
public Object convert(Object source, TypeDescriptor sourceType, TypeDescriptor targetType) {
if (source == null) {
return null;
}
Map<?, ?> sourceMap = (Map<?, ?>) source;
if (sourceMap.isEmpty()) {
return sourceMap;
}
Map targetMap = CollectionFactory.createMap(targetType.getType(), sourceMap.size());
for (Object entry : sourceMap.entrySet()) {
Map.Entry sourceMapEntry = (Map.Entry) entry;
Object sourceKey = sourceMapEntry.getKey();
Object sourceValue = sourceMapEntry.getValue();
Object targetKey = this.conversionService.convert(sourceKey,
sourceType.getMapKeyTypeDescriptor(sourceKey),
targetType.getMapKeyTypeDescriptor(sourceKey));
Object targetValue = this.conversionService.convert(sourceValue,
sourceType.getMapValueTypeDescriptor(sourceValue),
targetType.getMapValueTypeDescriptor(sourceValue));
targetMap.put(targetKey, targetValue);
}
return targetMap;
}
}
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