001/* 002 * Copyright 2006-2008 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; 018 019/** 020 * H2 implementation of a {@link org.springframework.batch.item.database.PagingQueryProvider} using database specific features. 021 * 022 * @author Dave Syer 023 * @since 2.1 024 */ 025public class H2PagingQueryProvider extends AbstractSqlPagingQueryProvider { 026 027 @Override 028 public String generateFirstPageQuery(int pageSize) { 029 return SqlPagingQueryUtils.generateTopSqlQuery(this, false, buildTopClause(pageSize)); 030 } 031 032 @Override 033 public String generateRemainingPagesQuery(int pageSize) { 034 return SqlPagingQueryUtils.generateTopSqlQuery(this, true, buildTopClause(pageSize)); 035 } 036 037 private String buildTopClause(int pageSize) { 038 return new StringBuilder().append("TOP ").append(pageSize).toString(); 039 } 040 041 @Override 042 public String generateJumpToItemQuery(int itemIndex, int pageSize) { 043 int page = itemIndex / pageSize; 044 int offset = (page * pageSize) - 1; 045 offset = offset<0 ? 0 : offset; 046 047 String topClause = new StringBuilder().append("LIMIT ").append(offset).append(" 1").toString(); 048 return SqlPagingQueryUtils.generateTopJumpToQuery(this, topClause); 049 } 050 051}