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}