001/*
002 * Copyright 2006-2012 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.batch.item.database.support;
018
019import org.springframework.util.StringUtils;
020
021/**
022 * HSQLDB implementation of a {@link org.springframework.batch.item.database.PagingQueryProvider} using database specific features.
023 *
024 * @author Thomas Risberg
025 * @author Michael Minella
026 * @since 2.0
027 */
028public class HsqlPagingQueryProvider extends AbstractSqlPagingQueryProvider {
029
030        @Override
031        public String generateFirstPageQuery(int pageSize) {
032                return SqlPagingQueryUtils.generateTopSqlQuery(this, false, buildTopClause(pageSize));
033        }
034
035        @Override
036        public String generateRemainingPagesQuery(int pageSize) {
037                if(StringUtils.hasText(getGroupClause())) {
038                        return SqlPagingQueryUtils.generateGroupedTopSqlQuery(this, true, buildTopClause(pageSize));
039                }
040                else {
041                        return SqlPagingQueryUtils.generateTopSqlQuery(this, true, buildTopClause(pageSize));
042                }
043        }
044
045        private String buildTopClause(int pageSize) {
046                return new StringBuilder().append("TOP ").append(pageSize).toString();
047        }
048
049        @Override
050        public String generateJumpToItemQuery(int itemIndex, int pageSize) {
051                int page = itemIndex / pageSize;
052                int offset = (page * pageSize) - 1;
053                offset = offset<0 ? 0 : offset;
054
055                String topClause = new StringBuilder().append("LIMIT ").append(offset).append(" 1").toString();
056                return SqlPagingQueryUtils.generateTopJumpToQuery(this, topClause);
057        }
058
059}