spring CollectionToDelimitedStringConverter 源码

  • 2022-08-12
  • 浏览 (601)

springboot CollectionToDelimitedStringConverter 代码

文件路径:/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/convert/CollectionToDelimitedStringConverter.java

/*
 * 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<ConvertiblePair> 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));
	}

}

相关信息

spring 源码目录

相关文章

spring ApplicationConversionService 源码

spring ArrayToDelimitedStringConverter 源码

spring CharArrayFormatter 源码

spring CharSequenceToObjectConverter 源码

spring DataSizeUnit 源码

spring DelimitedStringToArrayConverter 源码

spring DelimitedStringToCollectionConverter 源码

spring Delimiter 源码

spring DurationFormat 源码

spring DurationStyle 源码

0  赞