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.batch.item.database.PagingQueryProvider;
020import org.springframework.util.StringUtils;
021
022/**
023 * MySQL implementation of a {@link PagingQueryProvider} using database specific features.
024 *
025 * @author Thomas Risberg
026 * @author Michael Minella
027 * @since 2.0
028 */
029public class MySqlPagingQueryProvider extends AbstractSqlPagingQueryProvider {
030
031        @Override
032        public String generateFirstPageQuery(int pageSize) {
033                return SqlPagingQueryUtils.generateLimitSqlQuery(this, false, buildLimitClause(pageSize));
034        }
035
036        @Override
037        public String generateRemainingPagesQuery(int pageSize) {
038                if(StringUtils.hasText(getGroupClause())) {
039                        return SqlPagingQueryUtils.generateLimitGroupedSqlQuery(this, true, buildLimitClause(pageSize));
040                }
041                else {
042                        return SqlPagingQueryUtils.generateLimitSqlQuery(this, true, buildLimitClause(pageSize));
043                }
044        }
045
046        private String buildLimitClause(int pageSize) {
047                return new StringBuilder().append("LIMIT ").append(pageSize).toString();
048        }
049
050        @Override
051        public String generateJumpToItemQuery(int itemIndex, int pageSize) {
052                int page = itemIndex / pageSize;
053                int offset = (page * pageSize) - 1;
054                offset = offset<0 ? 0 : offset;
055
056                String limitClause = new StringBuilder().append("LIMIT ").append(offset).append(", 1").toString();
057                return SqlPagingQueryUtils.generateLimitJumpToQuery(this, limitClause);
058        }
059
060}