Apache POI Generate xls

ExportToExcel

public void exportToExcel(Window mainWindow){
  	//String title; 
		// String[] Headers TableColumnsDef. , Data, outputStream
		HSSFWorkbook workbook = new HSSFWorkbook();
		HSSFSheet sheet = workbook.createSheet("Export");
		
		// Header Style
		HSSFCellStyle style = workbook.createCellStyle();
		style.setFillForegroundColor(HSSFColor.SKY_BLUE.index);
		style.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);
		style.setBorderBottom(HSSFCellStyle.BORDER_THIN);
		style.setBorderLeft(HSSFCellStyle.BORDER_THIN);
		style.setBorderRight(HSSFCellStyle.BORDER_THIN);
		style.setBorderTop(HSSFCellStyle.BORDER_THIN);
		style.setAlignment(HSSFCellStyle.ALIGN_CENTER);

		HSSFFont font = workbook.createFont();
		font.setColor(HSSFColor.VIOLET.index);
		font.setFontHeightInPoints((short) 12);
		font.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
		style.setFont(font);
		
		// Body Style
		HSSFCellStyle style2 = workbook.createCellStyle();
//		style2.setFillForegroundColor(HSSFColor.LIGHT_YELLOW.index);
		style2.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);
		style2.setBorderBottom(HSSFCellStyle.BORDER_THIN);
		style2.setBorderLeft(HSSFCellStyle.BORDER_THIN);
		style2.setBorderRight(HSSFCellStyle.BORDER_THIN);
		style2.setBorderTop(HSSFCellStyle.BORDER_THIN);
		style2.setAlignment(HSSFCellStyle.ALIGN_CENTER);
		style2.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);

		HSSFFont font2 = workbook.createFont();
		font.setBoldweight(HSSFFont.BOLDWEIGHT_NORMAL);
		style2.setFont(font2);
		
		// Create Title Row
		HSSFRow row = sheet.createRow(0);
		for (int i=0; i< TableColumnsDef.PSI_COLS_NAME.length; i++){
			HSSFCell cell = row.createCell(i);
			cell.setCellStyle(style);
			HSSFRichTextString text = new HSSFRichTextString(TableColumnsDef.PSI_COLS_NAME[i]);
			cell.setCellValue(text);
		}
		
		// Create Body
		SQLContainer container = DatabaseUtil.getInstance().getPsiContainer();
		for (int i=0; i<container.size(); i++){
			Object id = container.getIdByIndex(i);
			Item item = container.getItem(id);
			row = sheet.createRow(i+1);
			
			for (int j=0; j<TableColumnsDef.PSI_COLS_ORDER.length; j++){
				HSSFCell cell = row.createCell(j);
				
				HSSFRichTextString text = new HSSFRichTextString(item.getItemProperty(TableColumnsDef.PSI_COLS_ORDER[j]).toString());
				cell.setCellValue(text);
			}
		}
		
		
		// download
		File tempFile = null;
		FileOutputStream fileOut = null;
		try {
			tempFile = File.createTempFile("tmp", ".xls");
			fileOut = new FileOutputStream(tempFile);
			workbook.write(fileOut);
			mainWindow.open(new FileResource(tempFile, mainWindow.getApplication()));
		} catch (IOException e){
			System.out.println("failed with IOException");
		} finally {
			tempFile.deleteOnExit();
			try {
				fileOut.close();
			} catch (IOException e){
				
			}
		}
	}