org.springframework.core.convert.ConversionService Maven / Gradle / Ivy
/*
* Copyright 2002-2017 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.core.convert;
import org.springframework.lang.Nullable;
/**
* A service interface for type conversion. This is the entry point into the convert system.
* Call {@link #convert(Object, Class)} to perform a thread-safe type conversion using this system.
*
* @author Keith Donald
* @author Phillip Webb
* @since 3.0
*/
public interface ConversionService {
/**
* Return {@code true} if objects of {@code sourceType} can be converted to the {@code targetType}.
* If this method returns {@code true}, it means {@link #convert(Object, Class)} is capable
* of converting an instance of {@code sourceType} to {@code targetType}.
*
Special note on collections, arrays, and maps types:
* For conversion between collection, array, and map types, this method will return {@code true}
* even though a convert invocation may still generate a {@link ConversionException} if the
* underlying elements are not convertible. Callers are expected to handle this exceptional case
* when working with collections and maps.
* @param sourceType the source type to convert from (may be {@code null} if source is {@code null})
* @param targetType the target type to convert to (required)
* @return {@code true} if a conversion can be performed, {@code false} if not
* @throws IllegalArgumentException if {@code targetType} is {@code null}
*/
boolean canConvert(@Nullable Class sourceType, Class targetType);
/**
* Return {@code true} if objects of {@code sourceType} can be converted to the {@code targetType}.
* The TypeDescriptors provide additional context about the source and target locations
* where conversion would occur, often object fields or property locations.
*
If this method returns {@code true}, it means {@link #convert(Object, TypeDescriptor, TypeDescriptor)}
* is capable of converting an instance of {@code sourceType} to {@code targetType}.
*
Special note on collections, arrays, and maps types:
* For conversion between collection, array, and map types, this method will return {@code true}
* even though a convert invocation may still generate a {@link ConversionException} if the
* underlying elements are not convertible. Callers are expected to handle this exceptional case
* when working with collections and maps.
* @param sourceType context about the source type to convert from
* (may be {@code null} if source is {@code null})
* @param targetType context about the target type to convert to (required)
* @return {@code true} if a conversion can be performed between the source and target types,
* {@code false} if not
* @throws IllegalArgumentException if {@code targetType} is {@code null}
*/
boolean canConvert(@Nullable TypeDescriptor sourceType, TypeDescriptor targetType);
/**
* Convert the given {@code source} to the specified {@code targetType}.
* @param source the source object to convert (may be {@code null})
* @param targetType the target type to convert to (required)
* @return the converted object, an instance of targetType
* @throws ConversionException if a conversion exception occurred
* @throws IllegalArgumentException if targetType is {@code null}
*/
@Nullable
T convert(@Nullable Object source, Class targetType);
/**
* Convert the given {@code source} to the specified {@code targetType}.
* The TypeDescriptors provide additional context about the source and target locations
* where conversion will occur, often object fields or property locations.
* @param source the source object to convert (may be {@code null})
* @param sourceType context about the source type to convert from
* (may be {@code null} if source is {@code null})
* @param targetType context about the target type to convert to (required)
* @return the converted object, an instance of {@link TypeDescriptor#getObjectType() targetType}
* @throws ConversionException if a conversion exception occurred
* @throws IllegalArgumentException if targetType is {@code null},
* or {@code sourceType} is {@code null} but source is not {@code null}
*/
@Nullable
Object convert(@Nullable Object source, @Nullable TypeDescriptor sourceType, TypeDescriptor targetType);
}