poi 自动解析Excel公式（方法）

原文：http://poi.apache.org/spreadsheet/eval.html

FileInputStream fis = new FileInputStream("c:/temp/test.xls");
Workbook wb = new HSSFWorkbook(fis); //or new XSSFWorkbook("c:/temp/test.xls")
Sheet sheet = wb.getSheetAt(0);
//生成模板 解析 
FormulaEvaluator evaluator = wb.getCreationHelper().createFormulaEvaluator();

// suppose your formula is in B3
CellReference cellReference = new CellReference("B3"); 
Row row = sheet.getRow(cellReference.getRow());
Cell cell = row.getCell(cellReference.getCol()); 

CellValue cellValue = evaluator.evaluate(cell);

switch (cellValue.getCellType()) {
    case Cell.CELL_TYPE_BOOLEAN:
        System.out.println(cellValue.getBooleanValue());
        break;
    case Cell.CELL_TYPE_NUMERIC:
        System.out.println(cellValue.getNumberValue());
        break;
    case Cell.CELL_TYPE_STRING:
        System.out.println(cellValue.getStringValue());
        break;
    case Cell.CELL_TYPE_BLANK:
        break;
    case Cell.CELL_TYPE_ERROR:
        break;

    // CELL_TYPE_FORMULA will never happen
    case Cell.CELL_TYPE_FORMULA: 
        break;
}