org.springframework.core.convert.support.FallbackObjectToStringConverter Maven / Gradle / Ivy
/*
* Copyright 2002-2015 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.support;
import java.io.StringWriter;
import java.util.Collections;
import java.util.Set;
import org.springframework.core.convert.TypeDescriptor;
import org.springframework.core.convert.converter.ConditionalGenericConverter;
import org.springframework.lang.Nullable;
/**
* Simply calls {@link Object#toString()} to convert any supported object
* to a {@link String}.
*
* Supports {@link CharSequence}, {@link StringWriter}, and any class
* with a String constructor or one of the following static factory methods:
* {@code valueOf(String)}, {@code of(String)}, {@code from(String)}.
*
*
Used by the {@link DefaultConversionService} as a fallback if there
* are no other explicit to-String converters registered.
*
* @author Keith Donald
* @author Juergen Hoeller
* @author Sam Brannen
* @since 3.0
* @see ObjectToObjectConverter
*/
final class FallbackObjectToStringConverter implements ConditionalGenericConverter {
@Override
public Set getConvertibleTypes() {
return Collections.singleton(new ConvertiblePair(Object.class, String.class));
}
@Override
public boolean matches(TypeDescriptor sourceType, TypeDescriptor targetType) {
Class sourceClass = sourceType.getObjectType();
if (String.class == sourceClass) {
// no conversion required
return false;
}
return (CharSequence.class.isAssignableFrom(sourceClass) ||
StringWriter.class.isAssignableFrom(sourceClass) ||
ObjectToObjectConverter.hasConversionMethodOrConstructor(sourceClass, String.class));
}
@Override
@Nullable
public Object convert(@Nullable Object source, TypeDescriptor sourceType, TypeDescriptor targetType) {
return (source != null ? source.toString() : null);
}
}