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1   /*
2    * Copyright 2002-2006 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.gageot.excel.core;
18  
19  import java.io.IOException;
20  
21  import org.apache.poi.hssf.usermodel.HSSFCell;
22  
23  /***
24   * Callback interface used by ExcelTemplate's query methods.
25   * Implementations of this interface perform the actual work of extracting
26   * results from cells, but don't need to worry about exception handling.
27   * IOExceptions will be caught and handled correctly by the ExcelTemplate class.
28   *
29   * <p>In contrast to a SheetExtractor, a CellCallbackHandler object is
30   * typically stateful: It keeps the result state within the object, to be
31   * available for later inspection.
32   *
33   * @author David Gageot
34   * @see SheetExtractor
35   * @see RowCallbackHandler
36   * @see CellMapper
37   */
38  public interface CellCallbackHandler {
39  
40  	/***
41  	 * Implementations must implement this method to process each cell of data
42  	 * in the HSSFSheet. This method should extract the current value.
43  	 * Exactly what the implementation chooses to do is up to it;
44  	 * a trivial implementation might simply count cells,
45  	 * while another implementation might build an XML document.
46  	 * @param cell the HSSFCell to process
47  	 * @param rowNum the number of the current row
48  	 * @param columnNum the number of the current column
49  	 * @throws IOException if a IOException is encountered getting
50  	 * column values (that is, there's no need to catch IOException)
51  	 */
52  	void processCell (HSSFCell cell, int rowNum, int columnNum) throws IOException;
53  }