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Project of Generic Excel File Reader with Sample
There is a newer version: 1.3
/**
 * The MIT License
 *
 * Copyright (c) myjeeva.com
 * Copyright 2013 https://github.com/DouglasCAyers
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE. 
 * 
 */

package com.myjeeva.poi;

import java.util.LinkedHashMap;

import org.apache.commons.lang.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.poi.xssf.eventusermodel.XSSFSheetXMLHandler.SheetContentsHandler;

/**
 * 
 * Excel Worksheet Handler for XML SAX parsing (.xlsx document model) http://poi.apache.org/spreadsheet/how-to.html#xssf_sax_api
 * 
 * 
 * 
 * Inspired by Jeevanandam M. https://github.com/jeevatkm/excelReader
 * 
 * 
 * 
 * Usage: Provide a {@link ExcelRowContentCallback} callback
 * that will be provided a map representing a row of data from the file. The
 * keys will be the column headers and values the row data. Your callback class
 * encapsulates any business logic for processing the string data into dates,
 * numbers, etc to allow full customization of the parsing and processing logic.
 * 
 * 
 * @author https://github.com/DouglasCAyers
 * @author Jeevanandam M.
 * 
 * @since v1.1
 */
public class ExcelWorkSheetRowCallbackHandler implements SheetContentsHandler {

	private static final Log LOG = LogFactory
			.getLog(ExcelWorkSheetRowCallbackHandler.class);

	private static final int HEADER_ROW = 0;

	// once an entire row of data has been read, pass map to this callback for
	// processing
	private ExcelRowContentCallback rowCallback;

	// LinkedHashMaps are used so iteration order is predictable over insertion
	// order
	private LinkedHashMap currentRowMap; // map of column
															// headers => row
															// values (eg, 'A'
															// => 'White Shirts'
															// )
	private LinkedHashMap columnHeaders; // map of column
															// references =>
															// column headers
															// (eg, 'A' =>
															// 'Product Title' )
	private int currentRow;

	public ExcelWorkSheetRowCallbackHandler(
			ExcelRowContentCallback rowCallbackHandler) {
		this.rowCallback = rowCallbackHandler;
	}

	/**
	 * @see org.apache.poi.xssf.eventusermodel.XSSFSheetXMLHandler.SheetContentsHandler#startRow(int)
	 */
	@Override
	public void startRow(int rowNum) {

		this.currentRow = rowNum;

		if (this.currentRow == HEADER_ROW) {
			this.columnHeaders = new LinkedHashMap();
		} else {
			this.currentRowMap = new LinkedHashMap();

			// Add column header as key into current row map so that each entry
			// will exist.
			// This ensures each column header will be in the "currentRowMap"
			// when passed to the user callback.
			// Remember, the 'column headers map key' is the actual cell column
			// reference, it's value is the file column header value.
			// In the 'cell' method below, this empty string will be overwritten
			// with the file row value (if has one, else remains empty).
			for (String columnHeader : this.columnHeaders.values()) {
				this.currentRowMap.put(columnHeader, "");
			}

		}

	}

	/**
	 * @see org.apache.poi.xssf.eventusermodel.XSSFSheetXMLHandler.SheetContentsHandler#cell(java.lang.String,
	 *      java.lang.String)
	 */
	@Override
	public void cell(String cellReference, String formattedValue) {

		// Note, POI will not invoke this method if the cell
		// is blank or if it detects there's no more data in the row.
		// So don't count on this being invoked the same number of times each
		// row.
		// That's another reason why in above code we ensure each column header
		// is in the 'currentRowMap'.

		if (this.currentRow == HEADER_ROW) {
			this.columnHeaders.put(getColumnReference(cellReference),
					formattedValue);
		} else {
			String columnHeader = this.columnHeaders
					.get(getColumnReference(cellReference));
			this.currentRowMap.put(columnHeader, formattedValue);
		}

	}

	/**
	 * @see org.apache.poi.xssf.eventusermodel.XSSFSheetXMLHandler.SheetContentsHandler#endRow()
	 */
	@Override
	public void endRow() {

		if (this.currentRow > HEADER_ROW) {
			try {
				LOG.debug("rowNum=" + currentRow + ", map=" + currentRowMap);

				this.rowCallback.processRow(currentRow, currentRowMap);
			} catch (Exception e) {
				throw new RuntimeException("Error invoking callback", e);
			}
		}

	}

	/**
	 * @see org.apache.poi.xssf.eventusermodel.XSSFSheetXMLHandler.SheetContentsHandler#headerFooter(java.lang.String,
	 *      boolean, java.lang.String)
	 */
	@Override
	public void headerFooter(String text, boolean isHeader, String tagName) {
		// Not Used
	}

	/**
	 * Returns the alphabetic column reference from this cell reference.
	 * Example: Given 'A12' returns 'A' or given 'BA205' returns 'BA'
	 */
	private String getColumnReference(String cellReference) {

		if (StringUtils.isBlank(cellReference)) {
			return "";
		}

		return cellReference.split("[0-9]*$")[0];
	}
}