/*
* Copyright 2016-2017 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.repository.support;
import lombok.experimental.UtilityClass;
import java.util.List;
import java.util.function.LongSupplier;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageImpl;
import org.springframework.data.domain.Pageable;
import org.springframework.util.Assert;
/**
* Support for query execution using {@link Pageable}. Using {@link PageableExecutionUtils} assumes that data queries
* are cheaper than {@code COUNT} queries and so some cases can take advantage of optimizations.
*
* @author Mark Paluch
* @author Oliver Gierke
* @author Christoph Strobl
* @since 1.13
*/
@UtilityClass
public class PageableExecutionUtils {
/**
* Constructs a {@link Page} based on the given {@code content}, {@link Pageable} and {@link Supplier} applying
* optimizations. The construction of {@link Page} omits a count query if the total can be determined based on the
* result size and {@link Pageable}.
*
* @param content must not be {@literal null}.
* @param pageable must not be {@literal null}.
* @param totalSupplier must not be {@literal null}.
* @return the {@link Page}.
*/
public static <T> Page<T> getPage(List<T> content, Pageable pageable, LongSupplier totalSupplier) {
Assert.notNull(content, "Content must not be null!");
Assert.notNull(pageable, "Pageable must not be null!");
Assert.notNull(totalSupplier, "TotalSupplier must not be null!");
if (pageable.isUnpaged() || pageable.getOffset() == 0) {
if (pageable.isUnpaged() || pageable.getPageSize() > content.size()) {
return new PageImpl<>(content, pageable, content.size());
}
return new PageImpl<>(content, pageable, totalSupplier.getAsLong());
}
if (content.size() != 0 && pageable.getPageSize() > content.size()) {
return new PageImpl<>(content, pageable, pageable.getOffset() + content.size());
}
return new PageImpl<>(content, pageable, totalSupplier.getAsLong());
}
}