org.springframework.core.convert.support.IdToEntityConverter Maven / Gradle / Ivy
/*
* Copyright 2002-2014 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.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.Collections;
import java.util.Set;
import org.springframework.core.convert.ConversionService;
import org.springframework.core.convert.TypeDescriptor;
import org.springframework.core.convert.converter.ConditionalGenericConverter;
import org.springframework.util.ClassUtils;
import org.springframework.util.ReflectionUtils;
/**
* Converts an entity identifier to a entity reference by calling a static finder method
* on the target entity type.
*
* For this converter to match, the finder method must be static, have the signature
* {@code find[EntityName]([IdType])}, and return an instance of the desired entity type.
*
* @author Keith Donald
* @author Juergen Hoeller
* @since 3.0
*/
final class IdToEntityConverter implements ConditionalGenericConverter {
private final ConversionService conversionService;
public IdToEntityConverter(ConversionService conversionService) {
this.conversionService = conversionService;
}
@Override
public Set getConvertibleTypes() {
return Collections.singleton(new ConvertiblePair(Object.class, Object.class));
}
@Override
public boolean matches(TypeDescriptor sourceType, TypeDescriptor targetType) {
Method finder = getFinder(targetType.getType());
return (finder != null &&
this.conversionService.canConvert(sourceType, TypeDescriptor.valueOf(finder.getParameterTypes()[0])));
}
@Override
public Object convert(Object source, TypeDescriptor sourceType, TypeDescriptor targetType) {
if (source == null) {
return null;
}
Method finder = getFinder(targetType.getType());
Object id = this.conversionService.convert(
source, sourceType, TypeDescriptor.valueOf(finder.getParameterTypes()[0]));
return ReflectionUtils.invokeMethod(finder, source, id);
}
private Method getFinder(Class entityClass) {
String finderMethod = "find" + getEntityName(entityClass);
Method[] methods;
boolean localOnlyFiltered;
try {
methods = entityClass.getDeclaredMethods();
localOnlyFiltered = true;
}
catch (SecurityException ex) {
// Not allowed to access non-public methods...
// Fallback: check locally declared public methods only.
methods = entityClass.getMethods();
localOnlyFiltered = false;
}
for (Method method : methods) {
if (Modifier.isStatic(method.getModifiers()) && method.getName().equals(finderMethod) &&
method.getParameterTypes().length == 1 && method.getReturnType().equals(entityClass) &&
(localOnlyFiltered || method.getDeclaringClass().equals(entityClass))) {
return method;
}
}
return null;
}
private String getEntityName(Class entityClass) {
String shortName = ClassUtils.getShortName(entityClass);
int lastDot = shortName.lastIndexOf('.');
if (lastDot != -1) {
return shortName.substring(lastDot + 1);
}
else {
return shortName;
}
}
}