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1   /*
2    * Copyright 2006-2012 the original author or authors.
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  
17  package org.springframework.batch.item.database.support;
18  
19  import org.springframework.util.StringUtils;
20  
21  /**
22   * HSQLDB implementation of a {@link org.springframework.batch.item.database.PagingQueryProvider} using database specific features.
23   *
24   * @author Thomas Risberg
25   * @author Michael Minella
26   * @since 2.0
27   */
28  public class HsqlPagingQueryProvider extends AbstractSqlPagingQueryProvider {
29  
30  	@Override
31  	public String generateFirstPageQuery(int pageSize) {
32  		return SqlPagingQueryUtils.generateTopSqlQuery(this, false, buildTopClause(pageSize));
33  	}
34  
35  	@Override
36  	public String generateRemainingPagesQuery(int pageSize) {
37  		if(StringUtils.hasText(getGroupClause())) {
38  			return SqlPagingQueryUtils.generateGroupedTopSqlQuery(this, true, buildTopClause(pageSize));
39  		}
40  		else {
41  			return SqlPagingQueryUtils.generateTopSqlQuery(this, true, buildTopClause(pageSize));
42  		}
43  	}
44  
45  	private String buildTopClause(int pageSize) {
46  		return new StringBuilder().append("TOP ").append(pageSize).toString();
47  	}
48  
49  	@Override
50  	public String generateJumpToItemQuery(int itemIndex, int pageSize) {
51  		int page = itemIndex / pageSize;
52  		int offset = (page * pageSize) - 1;
53  		offset = offset<0 ? 0 : offset;
54  
55  		String topClause = new StringBuilder().append("LIMIT ").append(offset).append(" 1").toString();
56  		return SqlPagingQueryUtils.generateTopJumpToQuery(this, topClause);
57  	}
58  
59  }