org.springframework.core.convert.converter.Converter Maven / Gradle / Ivy
/*
* Copyright 2002-2022 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.converter;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
/**
* A converter converts a source object of type {@code S} to a target of type {@code T}.
*
* Implementations of this interface are thread-safe and can be shared.
*
*
Implementations may additionally implement {@link ConditionalConverter}.
*
* @author Keith Donald
* @author Josh Cummings
* @since 3.0
* @param the source type
* @param the target type
*/
@FunctionalInterface
public interface Converter {
/**
* Convert the source object of type {@code S} to target type {@code T}.
* @param source the source object to convert, which must be an instance of {@code S} (never {@code null})
* @return the converted object, which must be an instance of {@code T} (potentially {@code null})
* @throws IllegalArgumentException if the source cannot be converted to the desired target type
*/
@Nullable
T convert(S source);
/**
* Construct a composed {@link Converter} that first applies this {@link Converter}
* to its input, and then applies the {@code after} {@link Converter} to the
* result.
* @param after the {@link Converter} to apply after this {@link Converter}
* is applied
* @param the type of output of both the {@code after} {@link Converter}
* and the composed {@link Converter}
* @return a composed {@link Converter} that first applies this {@link Converter}
* and then applies the {@code after} {@link Converter}
* @since 5.3
*/
default Converter andThen(Converter after) {
Assert.notNull(after, "'after' Converter must not be null");
return (S s) -> {
T initialResult = convert(s);
return (initialResult != null ? after.convert(initialResult) : null);
};
}
}