Excel Converter

ExcelConverter.java

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Arrays;
import java.util.HashMap;

import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.util.CellRangeAddress;

import static org.apache.commons.lang3.StringEscapeUtils.escapeHtml4;

class Coordinate {
	private final int row;
	private final int col;

	public Coordinate(int row, int col) {
		this.row = row;
		this.col = col;
	}

	@Override
	public boolean equals(Object other) {
		if (this == other)
			return true;
		if (!(other instanceof Coordinate))
			return false;
		Coordinate c = (Coordinate) other;
		return row == c.row && col == c.col;
	}

	@Override
	public int hashCode() {
		return (row + "," + col).hashCode();
	}
}

abstract class ExcelFormatConverter {
	protected abstract String escape(String value);
	protected abstract String wrapCell(String component);
	protected abstract String componentSeparator();
	protected abstract String rowBeginning();
	protected abstract String rowEnding();
	protected abstract String fileBeginning();
	protected abstract String fileEnding();
	protected abstract String fileExtension();
	
	protected String cellToString(Cell cell) {
		int type = cell.getCellType();

		if (type == Cell.CELL_TYPE_FORMULA)
			type = cell.getCachedFormulaResultType();

		String ret;
		switch (type) {
		case Cell.CELL_TYPE_BOOLEAN:
			ret = this.escape(String.valueOf(cell.getBooleanCellValue()));
			break;
		case Cell.CELL_TYPE_NUMERIC:
			ret = this.escape(String.valueOf(cell.getNumericCellValue()));
			break;
		case Cell.CELL_TYPE_STRING:
			ret = this.escape(String.valueOf(cell.getStringCellValue()));
			break;
		case Cell.CELL_TYPE_BLANK:
		case Cell.CELL_TYPE_ERROR:
			ret = "";
			break;
		default:
			ret = this.escape(String.valueOf(cell));
			break;
		}
		
		return ret;
	}
	
	public void convert(File inFile) throws IOException {
		String inFileName = inFile.getName();
		String extension = inFileName.substring(inFileName.lastIndexOf('.') + 1);
		FileInputStream fis = new FileInputStream(inFile);

		Workbook wb;
		if (extension.equals("xls")) {
			wb = new HSSFWorkbook(fis);
		} else {
			assert extension.equals("xlsx");
			wb = new XSSFWorkbook(fis);
		}

		int numSheets = wb.getNumberOfSheets();
		for (int sheetIndex = 0; sheetIndex < numSheets; ++sheetIndex) {
			HashMap<Coordinate, String> cells = new HashMap<Coordinate, String>();
			StringBuffer outputBuffer = new StringBuffer();
			Sheet sheet = wb.getSheetAt(sheetIndex);

			int minRow = Integer.MAX_VALUE;
			int maxRow = -1;
			int minCol = Integer.MAX_VALUE;
			int maxCol = -1;

			for (Row row : sheet) {
				for (Cell cell : row) {
					int r = cell.getRowIndex();
					int c = cell.getColumnIndex();
					Coordinate coord = new Coordinate(r, c);
					String component = this.cellToString(cell);
					
					if (component != "") {
						cells.put(coord, component);
						minRow = Math.min(minRow, r);
						maxRow = Math.max(maxRow, r);
						minCol = Math.min(minCol, c);
						maxCol = Math.max(maxCol, c);
					}
				}
			}
			
			 int numMergedRegions = sheet.getNumMergedRegions();
			 for (int i = 0; i < numMergedRegions; ++i) {
				 CellRangeAddress region = sheet.getMergedRegion(i);
				 String val = cells.get(new Coordinate(region.getFirstRow(), region.getFirstColumn()));
				 
				 for (int r = region.getFirstRow(); r <= region.getLastRow(); ++r) {
					 for (int c = region.getFirstColumn(); c <= region.getLastColumn(); ++c) {
						 cells.put(new Coordinate(r, c), val);
					 }
				 }
			 }
			 
			 outputBuffer.append(this.fileBeginning());
			 for (int r = minRow; r <= maxRow; ++r) {
				 outputBuffer.append(this.rowBeginning());
				 for (int c = minCol; c <= maxCol; ++c) {
					 String component = cells.get(new Coordinate(r, c));
					 if (component == null) {
						 component = "";
					 }
					 component = this.wrapCell(component);
					 outputBuffer.append(component);
					 if (c != maxCol) {
						 outputBuffer.append(this.componentSeparator());
					 }
				 }
				 outputBuffer.append(this.rowEnding());
			 }
			 outputBuffer.append(this.fileEnding());
			
			 int sheetNumber = sheetIndex + 1;
			 String outPath = inFile.getAbsoluteFile().getParent() + "/" + inFileName + "_sheet" + sheetNumber + "." + this.fileExtension();
			 System.out.println(outPath);
			 FileOutputStream fos = new FileOutputStream(new File(outPath));
			 fos.write(outputBuffer.toString().getBytes());
			 fos.close();
		}
		
		wb.close();
	}
	
}

class ExcelToCSVConverter extends ExcelFormatConverter {
	@Override
	protected String escape(String val) {
		return val.replace("\"", "\"\"");
	}

	@Override
	protected String wrapCell(String component) {
		return "\"" + component + "\"";
	}
	
	@Override
	protected String componentSeparator() {
		return ",";
	}

	@Override
	protected String rowBeginning() {
		return "";
	}

	@Override
	protected String rowEnding() {
		return "\n";
	}

	@Override
	protected String fileBeginning() {
		return "";
	}

	@Override
	protected String fileEnding() {
		return "";
	}

	@Override
	protected String fileExtension() {
		return "csv";
	}
}

class ExcelToHTMLConverter extends ExcelFormatConverter {
	@Override
	protected String escape(String val) {
		return escapeHtml4(val);
	}

	@Override
	protected String wrapCell(String component) {
		return "<td>" + component + "</td>";
	}
	
	@Override
	protected String componentSeparator() {
		return "";
	}

	@Override
	protected String rowBeginning() {
		return "<tr>";
	}

	@Override
	protected String rowEnding() {
		return "</tr>\n";
	}

	@Override
	protected String fileBeginning() {
		String style = "<style type='text/css'>table {border-collapse: collapse;} table td {border: 1px solid #999; padding: 4px;}</style>";
		return "<html>\n" + style + "<body>\n<table>\n";
	}

	@Override
	protected String fileEnding() {
		return "</table>\n</body>\n</html>";
	}

	@Override
	protected String fileExtension() {
		return "html";
	}
}

public class ExcelConverter {
	public static void main(String[] args) throws IOException {
		if (!(args.length == 2 && (args[0].equals("csv") || args[0].equals("html")))) {
			System.out.println("Invalid Arguments");
			System.exit(1);
		}
		String fname = args[1];
		File in = new File(fname);

		ExcelFormatConverter converter;
		
		if (args[0].equals("csv"))
			converter = new ExcelToCSVConverter();
		else
			converter = new ExcelToHTMLConverter();
		
		converter.convert(in);
		
		System.exit(1);
	}

}