/*
* Copyright 2002-2012 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
*
* http://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.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Collections;
import java.util.Set;
import org.springframework.core.convert.ConversionFailedException;
import org.springframework.core.convert.TypeDescriptor;
import org.springframework.core.convert.converter.ConditionalGenericConverter;
import org.springframework.util.ClassUtils;
import org.springframework.util.ReflectionUtils;
/**
* Generic Converter that attempts to convert a source Object to a target type
* by delegating to methods on the target type.
*
* <p>Calls the static {@code valueOf(sourceType)} method on the target type
* to perform the conversion, if such a method exists. Else calls the target type's
* Constructor that accepts a single sourceType argument, if such a Constructor exists.
* Else throws a ConversionFailedException.
*
* @author Keith Donald
* @author Juergen Hoeller
* @since 2.0
*/
final class ObjectToObjectConverter implements ConditionalGenericConverter {
public Set<ConvertiblePair> getConvertibleTypes() {
return Collections.singleton(new ConvertiblePair(Object.class, Object.class));
}
public boolean matches(TypeDescriptor sourceType, TypeDescriptor targetType) {
if (sourceType.getType().equals(targetType.getType())) {
// no conversion required
return false;
}
return hasValueOfMethodOrConstructor(targetType.getType(), sourceType.getType());
}
public Object convert(Object source, TypeDescriptor sourceType, TypeDescriptor targetType) {
if (source == null) {
return null;
}
Class<?> sourceClass = sourceType.getType();
Class<?> targetClass = targetType.getType();
Method method = getValueOfMethodOn(targetClass, sourceClass);
try {
if (method != null) {
ReflectionUtils.makeAccessible(method);
return method.invoke(null, source);
}
else {
Constructor<?> constructor = getConstructor(targetClass, sourceClass);
if (constructor != null) {
return constructor.newInstance(source);
}
}
}
catch (InvocationTargetException ex) {
throw new ConversionFailedException(sourceType, targetType, source, ex.getTargetException());
}
catch (Throwable ex) {
throw new ConversionFailedException(sourceType, targetType, source, ex);
}
throw new IllegalStateException("No static valueOf(" + sourceClass.getName() +
") method or Constructor(" + sourceClass.getName() + ") exists on " + targetClass.getName());
}
static boolean hasValueOfMethodOrConstructor(Class<?> clazz, Class<?> sourceParameterType) {
return getValueOfMethodOn(clazz, sourceParameterType) != null || getConstructor(clazz, sourceParameterType) != null;
}
private static Method getValueOfMethodOn(Class<?> clazz, Class<?> sourceParameterType) {
return ClassUtils.getStaticMethod(clazz, "valueOf", sourceParameterType);
}
private static Constructor<?> getConstructor(Class<?> clazz, Class<?> sourceParameterType) {
return ClassUtils.getConstructorIfAvailable(clazz, sourceParameterType);
}
}