com.blazebit.persistence.criteria.BlazeCriteria Maven / Gradle / Ivy
/*
* Copyright 2014 - 2021 Blazebit.
*
* 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 com.blazebit.persistence.criteria;
import com.blazebit.persistence.CriteriaBuilderFactory;
import com.blazebit.persistence.criteria.spi.BlazeCriteriaBuilderFactory;
import java.util.Iterator;
import java.util.ServiceLoader;
/**
* @author Christian Beikov
* @since 1.2.1
*/
public class BlazeCriteria {
private static volatile BlazeCriteriaBuilderFactory factory;
private BlazeCriteria() {
}
/**
* Creates a new {@link BlazeCriteriaBuilder} instance bound to the given criteria builder factory.
*
* @param criteriaBuilderFactory The criteria builder factory to which the persistence unit is bound
* @return A new {@link BlazeCriteriaBuilder}
*/
public static BlazeCriteriaBuilder get(CriteriaBuilderFactory criteriaBuilderFactory) {
BlazeCriteriaBuilderFactory factory = BlazeCriteria.factory;
if (factory == null) {
synchronized (BlazeCriteria.class) {
factory = BlazeCriteria.factory;
if (factory == null) {
Iterator iterator = ServiceLoader.load(BlazeCriteriaBuilderFactory.class).iterator();
if (iterator.hasNext()) {
factory = iterator.next();
BlazeCriteria.factory = factory;
} else {
throw new IllegalStateException("Could not find a service for BlazeCriteriaBuilderFactory. Are you missing the jpa-criteria-impl module?");
}
}
}
}
return factory.createCriteriaBuilder(criteriaBuilderFactory);
}
/**
* Creates a new {@link BlazeCriteriaQuery} instance bound to the given criteria builder factory with the given class as result type.
*
* @param criteriaBuilderFactory The criteria builder factory to which the persistence unit is bound
* @param clazz The result type of the created query
* @param The type of the query result
* @return A new {@link BlazeCriteriaQuery}
*/
public static BlazeCriteriaQuery get(CriteriaBuilderFactory criteriaBuilderFactory, Class clazz) {
return get(criteriaBuilderFactory).createQuery(clazz);
}
}