anicetkeric / Java-Excel

Apache POI – Reading and Writing Excel file in Java

Java-Excel - Maven Simple Project

Apache POI – Reading and Writing Excel file with Java using Mysql

Overview

Apache POI provides excellent support for working with Microsoft Excel documents. Apache POI is able to handle both XLS and XLSX formats of spreadsheets.

MYSQL DATABASE

use book_db database

Create database and tables

CREATE TABLE IF NOT EXISTS `book` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `title` varchar(35) NOT NULL,
  `author` varchar(35) NOT NULL,
  `price` double NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;

JAVA

###Apache POI Maven Dependencies

<!-- https://mvnrepository.com/artifact/org.apache.poi/poi -->
<dependency>
    <groupId>org.apache.poi</groupId>
    <artifactId>poi</artifactId>
    <version>3.17</version>
</dependency>

<!-- https://mvnrepository.com/artifact/org.apache.poi/poi-ooxml -->
<dependency>
    <groupId>org.apache.poi</groupId>
    <artifactId>poi-ooxml</artifactId>
    <version>3.17</version>
</dependency>

<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.22</version>
</dependency>

Apache POI example program to read excel file to the list of book and insert in Mysql database.

	
	private static final EnumMap<CellType, Function<Cell,Object>>
			EXCEL_CELL_VALUE = new EnumMap<>(CellType.class);

	static {
		EXCEL_CELL_VALUE.put(CellType.BLANK, null);
		EXCEL_CELL_VALUE.put(CellType.BOOLEAN, Cell::getBooleanCellValue);
		EXCEL_CELL_VALUE.put(CellType.STRING, Cell::getStringCellValue);
		EXCEL_CELL_VALUE.put(CellType.NUMERIC, cell -> {
			if (DateUtil.isCellDateFormatted(cell)) {
				return cell.getDateCellValue();
			} else {
				return cell.getNumericCellValue();
			}
		});
	}
	
	
	/**
	 * read all row in Excel file
	 * @param excelFilePath path of file
	 * @return list of {@link Book}
	 */
	public List<Book> readBookFromExcelFile(String excelFilePath) {
		List<Book> bookList = new ArrayList<>();

		try (Workbook workbook = getWorkbook(excelFilePath)) {

			Sheet sheet = workbook.getSheetAt(0);

			//get header number
			Row header = sheet.getRow(0);
			String headeridNumber = header.getCell(0).getStringCellValue();
			String headerTitleNumber = header.getCell(1).getStringCellValue();
			String headerAuthorNumber = header.getCell(2).getStringCellValue();
			String headerPriceNumber = header.getCell(3).getStringCellValue();


			if (headeridNumber.equalsIgnoreCase("Id")
					&& headerTitleNumber.equalsIgnoreCase("Title")
					&& headerAuthorNumber.equalsIgnoreCase("Author")
					&& headerPriceNumber.equalsIgnoreCase("Price")) {

				sheet.forEach(row -> {
					// skip header
					if (row.getRowNum() != 0){
						bookList.add(transformer(row));
					}
				});

			} else {
				throw new ExcelFileException("File not compatible. please verify the columns name");
			}

			return bookList;
		} catch (IOException e) {
			throw new ExcelFileException("Cannot read the file: "+ e.getMessage());
		}
	}
	/**
	 * @param excelFilePath path of file
	 * @return Workbook
	 */
	private Workbook getWorkbook(String excelFilePath){
		Workbook workbook;

		try{
			try (FileInputStream inputStream = new FileInputStream(new File(excelFilePath))) {
				if (excelFilePath.endsWith("xlsx")) {
					workbook = new XSSFWorkbook(inputStream);
				} else {
					throw new ExcelFileException("The specified file is not Excel file");
				}
			}
		}catch(SecurityException | IOException  e){
			throw new ExcelFileException("The specified file is not Excel file");
		}

		return workbook;
	}


	/**
	 * transform excel row in Book object
	 * @param excelRoow excel file row
	 * @return object of {@link Book}
	 */
	private Book transformer(Row excelRoow){
		Book book = new Book();
		book.setTitle((String) getCellValue(excelRoow.getCell(1)));
		book.setAuthor((String) getCellValue(excelRoow.getCell(2)));
		book.setPrice((Double) getCellValue(excelRoow.getCell(3)));

		return book;
	}

	/**
	 * @param cell Row cell
	 * @return Object row
	 */
	private Object getCellValue(Cell cell) {
		try{
			return EXCEL_CELL_VALUE.get(cell.getCellTypeEnum()).apply(cell);
		}catch (Exception e){
			LOGGER.log(Level.WARNING, String.format("Cannot get cell value %s", e.getMessage()));
			return null;
		}
	}
	

Output.java

	private static final String EXCEL_FILE_INPUT_PATH = "book.xlsx";
	private static final String EXCEL_FILE_OUTPUT_PATH = "book-java.xlsx";
	private static final IBookDao bookDao = new BookDaoImpl();

	public static void main(String[] args) {
		readFile();
	}

	/**
	 * read datas in Excel file
	 */
	private static void readFile() {

		ExcelFileUtils reader = new ExcelFileUtils();
		List<Book> books;

		// get All row in file
		books = reader.readBookFromExcelFile(EXCEL_FILE_INPUT_PATH);

		// inserting into the database
		books.forEach(bookDao::addBook);
	}
		   

Apache POI example program to select records in MySql database to Write Excel File

	
/**
	 * @param excelFilePath Excel file path
	 * @param books list of books
	 */
	public void writeBookListToFile(String excelFilePath, List<Book> books) {

		try (XSSFWorkbook workbook = new XSSFWorkbook()) {
			Sheet sheet = workbook.createSheet("Book");
			createHeaderRow(sheet);
			Iterator<Book> iterator = books.iterator();

			int rowIndex = 1;
			while(iterator.hasNext()){
				Book book = iterator.next();
				Row row = sheet.createRow(rowIndex++);
				Cell cell0 = row.createCell(0);
				cell0.setCellValue(book.getId());
				Cell cell1 = row.createCell(1);
				cell1.setCellValue(book.getTitle());
				Cell cell2 = row.createCell(2);
				cell2.setCellValue(book.getAuthor());
				Cell cell3 = row.createCell(3);
				cell3.setCellValue(book.getPrice());
			}

			//lets write the excel data to file now
			try (FileOutputStream outputStream = new FileOutputStream(excelFilePath)) {
				workbook.write(outputStream);
				LOGGER.log(Level.INFO, "File written successfully");
			}
		}
		catch (IOException e) {
		throw new ExcelFileException("Cannot read the file: "+ e.getMessage());
		}
	}


	/**
	 * Create header in Excel file
	 * @param sheet Excel sheet
	 */
	private void createHeaderRow(Sheet sheet) {

		CellStyle cellStyle = sheet.getWorkbook().createCellStyle();
		Font font = sheet.getWorkbook().createFont();
		font.setBold(true);
		font.setFontHeightInPoints((short) 12);
		cellStyle.setFont(font);

		cellStyle.setAlignment(HorizontalAlignment.CENTER);

		Row row = sheet.createRow(0);
		Cell cellId = row.createCell(0);
		cellId.setCellStyle(cellStyle);
		cellId.setCellValue("Id");

		Cell cellTitle = row.createCell(1);
		cellTitle.setCellStyle(cellStyle);
		cellTitle.setCellValue("Title");

		Cell cellAuthor = row.createCell(2);
		cellAuthor.setCellStyle(cellStyle);
		cellAuthor.setCellValue("Author");

		Cell cellPrice = row.createCell(3);
		cellPrice.setCellStyle(cellStyle);
		cellPrice.setCellValue("Price");
	}

Output.java

        private static final String EXCEL_FILE_INPUT_PATH = "book.xlsx";
	private static final String EXCEL_FILE_OUTPUT_PATH = "book-java.xlsx";
	private static final IBookDao bookDao = new BookDaoImpl();

	public static void main(String[] args) {
		writeFile();
	}

	/**
	 * read data in database and create new file
	 */
	private static void writeFile() {
		List<Book> books = bookDao.bookList();
		ExcelFileUtils writer = new ExcelFileUtils();
		writer.writeBookListToFile(EXCEL_FILE_OUTPUT_PATH, books);
	}

Apache POI Example – Read and write Excel Formula