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Spring Data module for JPA repositories.
/*
* Copyright 2008-2014 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
*
* 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.data.jpa.domain;
import static org.springframework.data.jpa.domain.Specifications.CompositionType.*;
import java.io.Serializable;
import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Predicate;
import javax.persistence.criteria.Root;
import org.springframework.util.Assert;
/**
* Helper class to easily combine {@link Specification} instances.
*
* @author Oliver Gierke
* @author Thomas Darimont
*/
public class Specifications implements Specification, Serializable {
private static final long serialVersionUID = 1L;
private final Specification spec;
/**
* Creates a new {@link Specifications} wrapper for the given {@link Specification}.
*
* @param spec can be {@literal null}.
*/
private Specifications(Specification spec) {
this.spec = spec;
}
/**
* Simple static factory method to add some syntactic sugar around a {@link Specification}.
*
* @param
* @param spec can be {@literal null}.
* @return
*/
public static Specifications where(Specification spec) {
return new Specifications(spec);
}
/**
* ANDs the given {@link Specification} to the current one.
*
* @param
* @param other can be {@literal null}.
* @return
*/
public Specifications and(Specification other) {
return new Specifications(new ComposedSpecification(spec, other, AND));
}
/**
* ORs the given specification to the current one.
*
* @param
* @param other can be {@literal null}.
* @return
*/
public Specifications or(Specification other) {
return new Specifications(new ComposedSpecification(spec, other, OR));
}
/**
* Negates the given {@link Specification}.
*
* @param
* @param spec can be {@literal null}.
* @return
*/
public static Specifications not(Specification spec) {
return new Specifications(new NegatedSpecification(spec));
}
/*
* (non-Javadoc)
* @see org.springframework.data.jpa.domain.Specification#toPredicate(javax.persistence.criteria.Root, javax.persistence.criteria.CriteriaQuery, javax.persistence.criteria.CriteriaBuilder)
*/
public Predicate toPredicate(Root root, CriteriaQuery query, CriteriaBuilder builder) {
return spec == null ? null : spec.toPredicate(root, query, builder);
}
/**
* Enum for the composition types for {@link Predicate}s.
*
* @author Thomas Darimont
*/
enum CompositionType {
AND {
@Override
public Predicate combine(CriteriaBuilder builder, Predicate lhs, Predicate rhs) {
return builder.and(lhs, rhs);
}
},
OR {
@Override
public Predicate combine(CriteriaBuilder builder, Predicate lhs, Predicate rhs) {
return builder.or(lhs, rhs);
}
};
abstract Predicate combine(CriteriaBuilder builder, Predicate lhs, Predicate rhs);
}
/**
* A {@link Specification} that negates a given {@code Specification}.
*
* @author Thomas Darimont
* @since 1.6
*/
private static class NegatedSpecification implements Specification, Serializable {
private static final long serialVersionUID = 1L;
private final Specification spec;
/**
* Creates a new {@link NegatedSpecification} from the given {@link Specification}
*
* @param spec may be {@iteral null}
*/
public NegatedSpecification(Specification spec) {
this.spec = spec;
}
public Predicate toPredicate(Root root, CriteriaQuery query, CriteriaBuilder builder) {
return spec == null ? null : builder.not(spec.toPredicate(root, query, builder));
}
}
/**
* A {@link Specification} that combines two given {@code Specification}s via a given {@link CompositionType}.
*
* @author Thomas Darimont
* @since 1.6
*/
private static class ComposedSpecification implements Specification, Serializable {
private static final long serialVersionUID = 1L;
private final Specification lhs;
private final Specification rhs;
private final CompositionType compositionType;
/**
* Creates a new {@link ComposedSpecification} from the given {@link Specification} for the left-hand-side and the
* right-hand-side with the given {@link CompositionType}.
*
* @param lhs may be {@literal null}
* @param rhs may be {@literal null}
* @param compositionType must not be {@literal null}
*/
private ComposedSpecification(Specification lhs, Specification rhs, CompositionType compositionType) {
Assert.notNull(compositionType, "CompositionType must not be null!");
this.lhs = lhs;
this.rhs = rhs;
this.compositionType = compositionType;
}
/**
* Returns {@link Predicate} for the given {@link Root} and {@link CriteriaQuery} that is constructed via the given
* {@link CriteriaBuilder}.
*/
public Predicate toPredicate(Root root, CriteriaQuery query, CriteriaBuilder builder) {
Predicate otherPredicate = rhs == null ? null : rhs.toPredicate(root, query, builder);
Predicate thisPredicate = lhs == null ? null : lhs.toPredicate(root, query, builder);
return thisPredicate == null ? otherPredicate : otherPredicate == null ? thisPredicate : this.compositionType
.combine(builder, thisPredicate, otherPredicate);
}
}
}