spring-data-jpa JpaCountQueryCreator 源码
spring-data-jpa JpaCountQueryCreator 代码
文件路径：/spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/query/JpaCountQueryCreator.java
/*
* Copyright 2008-2022 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.data.jpa.repository.query;
import jakarta.persistence.criteria.CriteriaBuilder;
import jakarta.persistence.criteria.CriteriaQuery;
import jakarta.persistence.criteria.Expression;
import jakarta.persistence.criteria.Predicate;
import jakarta.persistence.criteria.Root;
import org.springframework.data.domain.Sort;
import org.springframework.data.repository.query.ReturnedType;
import org.springframework.data.repository.query.parser.PartTree;
import org.springframework.lang.Nullable;
/**
* Special {@link JpaQueryCreator} that creates a count projecting query.
*
* @author Oliver Gierke
* @author Marc Lefrançois
* @author Mark Paluch
* @author Greg Turnquist
*/
public class JpaCountQueryCreator extends JpaQueryCreator {
private boolean distinct;
/**
* Creates a new {@link JpaCountQueryCreator}.
*
* @param tree
* @param type
* @param builder
* @param provider
*/
public JpaCountQueryCreator(PartTree tree, ReturnedType type, CriteriaBuilder builder,
ParameterMetadataProvider provider) {
super(tree, type, builder, provider);
this.distinct = tree.isDistinct();
}
@Override
protected CriteriaQuery<? extends Object> createCriteriaQuery(CriteriaBuilder builder, ReturnedType type) {
return builder.createQuery(Long.class);
}
@Override
@SuppressWarnings("unchecked")
protected CriteriaQuery<? extends Object> complete(@Nullable Predicate predicate, Sort sort,
CriteriaQuery<? extends Object> query, CriteriaBuilder builder, Root<?> root) {
CriteriaQuery<? extends Object> select = query.select(getCountQuery(query, builder, root));
return predicate == null ? select : select.where(predicate);
}
@SuppressWarnings("rawtypes")
private Expression getCountQuery(CriteriaQuery<?> query, CriteriaBuilder builder, Root<?> root) {
return distinct ? builder.countDistinct(root) : builder.count(root);
}
}
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