POIFSFileSystem fs = new POIFSFileSystem(new FileInputStream("workbook.xls"));
       HSSFWorkbook wb = new HSSFWorkbook(fs);
       HSSFSheet sheet = wb.getSheet("new sheet");
      int starRow = 4;
      int rows = 5;
     
        sheet.shiftRows(starRow + 1, sheet.getLastRowNum(), rows,true,false);
        //Parameters:
        //startRow - the row to start shifting
        //endRow - the row to end shifting
        //n - the number of rows to shift
        //copyRowHeight - whether to copy the row height during the shift
        //resetOriginalRowHeight - whether to set the original row's height to the default
      
        starRow = starRow - 1;

        for (int i = 0; i < rows; i++) {
         HSSFRow sourceRow = null;
         HSSFRow targetRow = null;
         HSSFCell sourceCell = null;
         HSSFCell targetCell = null;
         short m;
         starRow = starRow + 1;
         sourceRow = sheet.getRow(starRow);
         targetRow = sheet.createRow(starRow + 1);
         targetRow.setHeight(sourceRow.getHeight());
 
         for (m = sourceRow.getFirstCellNum(); m < sourceRow.getLastCellNum(); m++) {
         sourceCell = sourceRow.getCell(m);
         targetCell = targetRow.createCell(m);
 
         //targetCell.setEncoding(sourceCell.getEncoding());
         targetCell.setCellStyle(sourceCell.getCellStyle());
         targetCell.setCellType(sourceCell.getCellType());
         targetCell.setCellValue(i);//設置值
         }
       }
     FileOutputStream fileOut = new FileOutputStream("workbook.xls");
        wb.write(fileOut);
        fileOut.close();
   }