官方介绍 HSSF is the POI Project's pure Java implementation of the Excel '97(-) file format. XSSF is the POI Project's pure Java implementation of the Excel OOXML (.xlsx) file format. 从官方文档中了解到：POI提供的HSSF包用于操作Excel '97(-)的.xls文件，而XSSF包则用于操作Excel之后的.xslx文件。 需要的jar包 POI官网上下载包并解压获取java操作excel文件必须的jar包：其中dom4j-1.6.1.jar和xbean.jar（下载地址： http://mirror./apache/xmlbeans/binaries/ 网站：
）并不包含在POI提供的jar包中，需要单独下载，否则程序会抛出异常：java.lang.ClassNotFoundException:org.apache.xmlbeans.XmlOptions。 具体代码 在Eclipse中创建一个java project，将上面列出来的jar包都加入到工程的classpath中，否则引用不到jar包会报错。 直接上代码（代码基本框架来自Apache POI官方网站，自行调整部分）： 创建excel文件并写入内容：
public static void createWorkbook() throws IOException {Workbook wb = new HSSFWorkbook();String safeName1 = WorkbookUtil.createSafeSheetName("[O'sheet1]");Sheet sheet1 = wb.createSheet(safeName1);CreationHelper createHelper = wb.getCreationHelper();// Create a row and put some cells in it. Rows are 0 based.Row row = sheet1.createRow((short) 0);// Create a cell and put a value in it.Cell cell = row.createCell(0);cell.setCellValue(1234);// Or do it on one line.row.createCell(2).setCellValue(createHelper.createRichTextString("This is a string"));row.createCell(3).setCellValue(true);// we style the second cell as a date (and time). It is important to// create a new cell style from the workbook otherwise you can end up// modifying the built in style and effecting not only this cell but// other cells.CellStyle cellStyle = wb.createCellStyle();cellStyle.setDataFormat(createHelper.createDataFormat().getFormat("m/d/yy h:mm"));cell = row.createCell(1);cell.setCellValue(new Date());cell.setCellStyle(cellStyle);// you can also set date as java.util.CalendarCellStyle cellStyle1 = wb.createCellStyle();cellStyle1.setDataFormat(createHelper.createDataFormat().getFormat("yyyyMMdd HH:mm:ss"));cellStyle1.setBorderBottom(CellStyle.BORDER_THIN);cellStyle1.setBottomBorderColor(IndexedColors.BLACK.getIndex());cellStyle1.setBorderLeft(CellStyle.BORDER_THIN);cellStyle1.setLeftBorderColor(IndexedColors.GREEN.getIndex());cellStyle1.setBorderRight(CellStyle.BORDER_THIN);cellStyle1.setRightBorderColor(IndexedColors.BLUE.getIndex());cellStyle1.setBorderTop(CellStyle.BORDER_MEDIUM_DASHED);cellStyle1.setTopBorderColor(IndexedColors.BLACK.getIndex());cell = row.createCell(4);cell.setCellValue(Calendar.getInstance());cell.setCellStyle(cellStyle1);FileOutputStream fileOut = new FileOutputStream("e:/test/workbook.xls");wb.write(fileOut);fileOut.close();}
读取excel文件的内容：
public static void readExcel() throws InvalidFormatException, IOException {// Use a fileWorkbook wb1 = WorkbookFactory.create(new File("e:/test/userinfo.xls"));Sheet sheet = wb1.getSheetAt(0);// Decide which rows to process// int rowStart = Math.min(10, sheet.getFirstRowNum());// int rowEnd = Math.max(40, sheet.getLastRowNum());int rowStart = sheet.getLastRowNum();int rowEnd = sheet.getLastRowNum() + 1;logger.info(sheet.getFirstRowNum());logger.info(sheet.getLastRowNum());for (int rowNum = rowStart; rowNum < rowEnd; rowNum++) {Row r = sheet.getRow(rowNum);int lastColumn = Math.max(r.getLastCellNum(), 10);logger.info(lastColumn);// To get the contents of a cell, you first need to know what kind// of cell it is (asking a string cell for its numeric contents will// get you a NumberFormatException for example). So, you will want// to switch on the cell's type, and then call the appropriate// getter for that cell.for (int cn = 0; cn < lastColumn; cn++) {// Cell cell = r.getCell(cn, Row.RETURN_BLANK_AS_NULL);Cell cell = r.getCell(cn);switch (cell.getCellType()) {case Cell.CELL_TYPE_STRING:logger.info(cell.getRichStringCellValue().getString());break;case Cell.CELL_TYPE_NUMERIC:if (DateUtil.isCellDateFormatted(cell)) {logger.info(cell.getDateCellValue());} else {logger.info(cell.getNumericCellValue());}break;case Cell.CELL_TYPE_BOOLEAN:logger.info(cell.getBooleanCellValue());break;case Cell.CELL_TYPE_FORMULA:logger.info(cell.getCellFormula());break;default:logger.info("empty");}}}}
下面给出一个具体的例子，实例中的excel文件内容如下：
我们的程序要做的事情是：根据第一行标题的顺序来读取每一行文件的内容，实际标题和内容的顺序是不确定的，但是我们要求按照给定的顺序输出文件内容。 代码如下：
public static void readUserInfo() throws InvalidFormatException,IOException {String[] titles = { "收费编号", "收费性质", "姓名", "家庭住址", "工作单位", "电话", "手机","小区楼号", "单元号", "楼层", "房间号", "建筑面积（㎡）", "面积依据", "A面积", "A超","A轻体", "B面积", "B超", "B轻体", "用户编号", "所属楼前表表号" };//用来存储标题和顺序的map，key为标题，value为顺序号Map<String, Integer> titleMap = new HashMap<String, Integer>();//将既定顺序写入mapfor (int i=0 ; i<titles.length; i++) {titleMap.put(titles[i], i);}Workbook wb = WorkbookFactory.create(new File("e:/test/userinfo.xls"));for (int numSheet = 0; numSheet < wb.getNumberOfSheets(); numSheet++) {Sheet xSheet = wb.getSheetAt(numSheet);if (xSheet == null) {continue;}// 获取第一行的标题内容Row tRow = xSheet.getRow(0);//存储标题顺序的数组Integer[] titleSort = new Integer[tRow.getLastCellNum()];//循环标题for (int titleNum = 0; titleNum < tRow.getLastCellNum(); titleNum++) {Cell tCell = tRow.getCell(titleNum);String title = "";if (tCell == null || "".equals(tCell)) {} else if (tCell.getCellType() == XSSFCell.CELL_TYPE_BOOLEAN) {// 布尔类型处理// logger.info(xCell.getBooleanCellValue());} else if (tCell.getCellType() == XSSFCell.CELL_TYPE_NUMERIC) {// 数值类型处理title = doubleToString(tCell.getNumericCellValue());} else {// 其他类型处理title = tCell.getStringCellValue();}//通过获取的标题，从map中读取顺讯号，写入保存标题顺序号的数组Integer ts = titleMap.get(title);if (ts != null) {titleSort[titleNum] = ts;}}// 循环行Rowfor (int rowNum = 1; rowNum < xSheet.getLastRowNum() + 1; rowNum++) {Row xRow = xSheet.getRow(rowNum);if (xRow == null) {continue;}// 循环列CellString[] v = new String[titleSort.length];for (int cellNum = 0; cellNum < titleSort.length; cellNum++) {Cell xCell = xRow.getCell(cellNum);String value = "";if (xCell == null || "".equals(xCell)) {} else if (xCell.getCellType() == XSSFCell.CELL_TYPE_BOOLEAN) {// 布尔类型处理 logger.info(xCell.getBooleanCellValue());} else if (xCell.getCellType() == XSSFCell.CELL_TYPE_NUMERIC) {// 数值类型处理value = doubleToString(xCell.getNumericCellValue());} else {// 其他类型处理value = xCell.getStringCellValue();}//按照标题顺序的编号来存储每一行记录v[titleSort[cellNum]] = value;//logger.info("v[" + titleSort[cellNum] + "] = " + v[titleSort[cellNum]]);}//循环结果数组，获取的与既定顺序相同for (int i = 0; i < v.length; i++) {logger.info(v[i]);}}}}
上段程序中用到的工具类doubleToString（将excel中的double类型转为String类型，处理了科学计数法形式的数）：
private static String doubleToString(double d) {String str = Double.valueOf(d).toString();// System.out.println(str);String result = "";if (str.indexOf("E") > 2) {int index = str.indexOf("E");int power = Integer.parseInt(str.substring(index + 1));BigDecimal value = new BigDecimal(str.substring(0, index));value = value.movePointRight(power);result = value.toString();} else {if (str.indexOf(".0") > 0)result = str.substring(0, str.indexOf(".0"));elseresult = str;}return result;}
目前对于POI的应用只限于此，并没有再深入，以后写了新的相关内容会继续补充，请大大们批评指正！
