public static void mergeWorkBook() throws Exception  {

         long startTime = System.currentTimeMillis();    //获取开始时间

         String fromPath = "exceldoc\\cases";// excel存放路径

         String toPath = "exceldoc/result/";// 保存新EXCEL路径

         // 新的excel 文件名

         String excelName = "汇总";

         // 创建新的excel

         HSSFWorkbook wbCreat = new HSSFWorkbook();

         File file = new File(fromPath);

         for (File excel : file.listFiles()) {

             // 打开已有的excel

             String strExcelPath = fromPath + "/" + excel.getName();

             // input 来源  ，output 目的地

             InputStream in = new FileInputStream(strExcelPath);

             HSSFWorkbook wb = new HSSFWorkbook(in);

             //获取工作簿的名称，不带前缀

             String bookName = excel.getName().substring(0,excel.getName().lastIndexOf("."));

             // i表示源工作簿 sheet 数量

             int sheetnum = wb.getNumberOfSheets();

             for (int i = 0; i < sheetnum; i++) {

                 //开始每个表的处理

                 HSSFSheet sheet = wb.getSheetAt(i);

                 // 目标工作簿创建同样的sheet名

                 String sheetName = sheet.getSheetName();

                 int firstRow = sheet.getFirstRowNum();

                 int lastRow = sheet.getLastRowNum();

                 System.out.println("workbook:"+bookName);

                 System.out.println("sheetName:"+sheetName);

                  //如果sheet的lastrow 是0 表示这个表没有内容,这张sheet就不用处理，继续处理下张sheet处理，用continue

                 if(lastRow == 0 ){

                     continue;

                 }

                 HSSFSheet sheetCreat = wbCreat.createSheet(bookName +"_"+ sheet.getSheetName());

                 //开始多行的处理

                 for (int j = firstRow; j <= lastRow   ; j++) {

                     // 创建新建excel Sheet的行

                     HSSFRow rowCreat = sheetCreat.createRow(j);

                     // 取得源有excel Sheet的行

                     HSSFRow row = sheet.getRow(j);

                     // 单元格式样

                     //如果行的内容为null ，说明行为空行，此行就跳过，继续下行的处理，用continue

                     if(null == row){

                         continue;

                     }

                     System.out.println("bookName:"+bookName+"|sheetName:"+sheetName+"|row:"+j);

                     int lastCell = row.getLastCellNum();

                     int firstCell = row.getFirstCellNum();

                     for (int k = firstCell; k < lastCell && lastCell >0; k++) {

                         String strVal ="";

                         if (null != row.getCell(k)) {

                            switch (row.getCell(k).getCellType()) {

                            case HSSFCell.CELL_TYPE_NUMERIC: // 数字   

                                DecimalFormat df = new DecimalFormat("#");

                                strVal = df.format(row.getCell(k).getNumericCellValue());                         

                                    break;

                            case HSSFCell.CELL_TYPE_STRING: // 字符串

                                strVal=row.getCell(k).getStringCellValue() + "";

                                    break;

                            case HSSFCell.CELL_TYPE_BOOLEAN: // Boolean

                                strVal= row.getCell(k).getBooleanCellValue()+ "";

                                    break;

                            case HSSFCell.CELL_TYPE_FORMULA: // 公式

                                strVal = row.getCell(k).getCellFormula() + "";

                                    break;

                            case HSSFCell.CELL_TYPE_BLANK: // 空值

                                strVal = "";

                                    break;

                            case HSSFCell.CELL_TYPE_ERROR: // 故障

                                    System.out.println(i+ j + "CELL_TYPE_ERROR");

                                    break;

                            default:

                                    System.out.print(i+ j + "未知类型   ");

                                    break;

                            }

                        //System.out.println(strVal);

                             rowCreat.createCell(k).setCellType(HSSFCell.CELL_TYPE_STRING);;

                             rowCreat.getCell(k).setCellValue(strVal+"");

                         }

                     }

                     System.out.println("单行处理完毕");

                 }

                 System.out.println("多行处理完毕");

             }

             System.out.println("多表处理完毕");

         }

         System.out.println("多个文件处理完毕");

         System.out.println(toPath + excelName + ".xls");

         FileOutputStream fileOut = new FileOutputStream(toPath + excelName + ".xls");

         wbCreat.write(fileOut);

         fileOut.close();

         HSSFWorkbook workbook = new HSSFWorkbook(new FileInputStream(toPath + excelName + ".xls"));

         System.out.println( workbook.getNumberOfSheets());

         long endTime = System.currentTimeMillis();    //获取结束时间

         System.out.println("程序运行时间：" + (endTime - startTime) + "ms");    //输出程序运行时间

    }

 if (null != row.getCell(k)) {

                            switch (row.getCell(k).getCellType()) {

                            case HSSFCell.CELL_TYPE_NUMERIC: // 数字   

                                DecimalFormat df = new DecimalFormat("#");

                                strVal = df.format(row.getCell(k).getNumericCellValue());                         

                                    break;

                            case HSSFCell.CELL_TYPE_STRING: // 字符串

                                strVal=row.getCell(k).getStringCellValue() + "";

                                    break;

                            case HSSFCell.CELL_TYPE_BOOLEAN: // Boolean

                                strVal= row.getCell(k).getBooleanCellValue()+ "";

                                    break;

                            case HSSFCell.CELL_TYPE_FORMULA: // 公式

                                strVal = row.getCell(k).getCellFormula() + "";

                                    break;

                            case HSSFCell.CELL_TYPE_BLANK: // 空值

                                strVal = "";

                                    break;

                            case HSSFCell.CELL_TYPE_ERROR: // 故障

                                    System.out.println(i+ j + "CELL_TYPE_ERROR");

                                    break;

                            default:

                                    System.out.print(i+ j + "未知类型   ");

                                    break;

                            }

                        //System.out.println(strVal);

                             rowCreat.createCell(k).setCellType(HSSFCell.CELL_TYPE_STRING);;

                             rowCreat.getCell(k).setCellValue(strVal+"");

                         }