org.springframework.boot.convert.CollectionToDelimitedStringConverter Maven / Gradle / Ivy
/*
* Copyright 2012-2019 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
*
* https://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.boot.convert;
import java.util.Collection;
import java.util.Collections;
import java.util.Set;
import java.util.stream.Collectors;
import org.springframework.core.convert.ConversionService;
import org.springframework.core.convert.TypeDescriptor;
import org.springframework.core.convert.converter.ConditionalGenericConverter;
/**
* Converts a Collection to a delimited String.
*
* @author Phillip Webb
*/
final class CollectionToDelimitedStringConverter implements ConditionalGenericConverter {
private final ConversionService conversionService;
CollectionToDelimitedStringConverter(ConversionService conversionService) {
this.conversionService = conversionService;
}
@Override
public Set getConvertibleTypes() {
return Collections.singleton(new ConvertiblePair(Collection.class, String.class));
}
@Override
public boolean matches(TypeDescriptor sourceType, TypeDescriptor targetType) {
TypeDescriptor sourceElementType = sourceType.getElementTypeDescriptor();
if (targetType == null || sourceElementType == null) {
return true;
}
return this.conversionService.canConvert(sourceElementType, targetType)
|| sourceElementType.getType().isAssignableFrom(targetType.getType());
}
@Override
public Object convert(Object source, TypeDescriptor sourceType, TypeDescriptor targetType) {
if (source == null) {
return null;
}
Collection sourceCollection = (Collection) source;
return convert(sourceCollection, sourceType, targetType);
}
private Object convert(Collection source, TypeDescriptor sourceType, TypeDescriptor targetType) {
if (source.isEmpty()) {
return "";
}
return source.stream().map((element) -> convertElement(element, sourceType, targetType))
.collect(Collectors.joining(getDelimiter(sourceType)));
}
private CharSequence getDelimiter(TypeDescriptor sourceType) {
Delimiter annotation = sourceType.getAnnotation(Delimiter.class);
return (annotation != null) ? annotation.value() : ",";
}
private String convertElement(Object element, TypeDescriptor sourceType, TypeDescriptor targetType) {
return String.valueOf(
this.conversionService.convert(element, sourceType.elementTypeDescriptor(element), targetType));
}
}