org.omnifaces.utils.reflect.Getter Maven / Gradle / Ivy
/*
* Copyright 2021 OmniFaces
*
* 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.omnifaces.utils.reflect;
import static java.util.Arrays.stream;
import java.beans.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.io.Serializable;
import java.lang.invoke.SerializedLambda;
import java.lang.reflect.Method;
import java.util.Objects;
import java.util.function.Function;
/**
*
* So we can extract method info from a method reference.
* Usage example:
*
* Map<Getter<YourEntity>, Object> criteria = new HashMap<>();
* criteria.put(YourEntity::getName, Like.startsWith(searchNameStartsWith));
* criteria.put(YourEntity::getCreated, Order.greaterThanOrEqualTo(searchStartDate));
* criteria.put(YourEntity::getType, searchTypes);
* criteria.put(YourEntity::isDeleted, false);
*
*
* And then later on in "the backend":
*
* criteria.forEach((getter, value) -> requiredCriteria.put(getter.getPropertyName(), value));
*
*
* This allows a type safe way of defining property names.
*
* Inspired by Lambda parameter names with reflection.
* NOTE: works only in Java 8u60 and newer.
*
* @param The generic base type.
* @author Bauke Scholtz
*/
public interface Getter extends Function, Serializable {
default SerializedLambda getSerializedLambda() {
try {
Method writeReplace = getClass().getDeclaredMethod("writeReplace");
writeReplace.setAccessible(true);
return (SerializedLambda) writeReplace.invoke(this);
}
catch (Exception e) {
throw new UnsupportedOperationException(e);
}
}
@SuppressWarnings("unchecked")
default Class getBaseType() {
String className = getSerializedLambda().getImplClass().replace("/", ".");
try {
return (Class) Class.forName(className, true, Thread.currentThread().getContextClassLoader());
}
catch (Exception e) {
throw new IllegalStateException(e);
}
}
default Method getMethod() {
String methodName = getSerializedLambda().getImplMethodName();
return stream(getBaseType().getDeclaredMethods())
.filter(method -> Objects.equals(method.getName(), methodName))
.findFirst().orElseThrow(IllegalStateException::new);
}
default String getPropertyName() {
Method method = getMethod();
BeanInfo beanInfo;
try {
beanInfo = Introspector.getBeanInfo(getBaseType());
}
catch (IntrospectionException e) {
throw new IllegalStateException(e);
}
return stream(beanInfo.getPropertyDescriptors())
.filter(property -> property.getReadMethod() != null && Objects.equals(property.getReadMethod().getName(), method.getName()))
.findFirst().orElseThrow(IllegalStateException::new)
.getName();
}
default Class getReturnType() {
return getMethod().getReturnType();
}
}