Java Web 怎么获取从jsp页面 上传文件的路径

public Workbook read(String fileName, boolean flag) throws Exception {
Workbook wb = null;
String extraFileName = "";
if (flag) {
extraFileName = this.getExtensionName(fileName);
if (!"XLS".equals(extraFileName.toUpperCase())) {
throw new BusinessException("文件格式不正确,必须为2003版的excel文件");
}

        File f = new File(fileName);
        FileInputStream is = new FileInputStream(f);
        POIFSFileSystem fs = new POIFSFileSystem(is);
        wb = new HSSFWorkbook(fs);
        is.close();
    } else {
        extraFileName = this.getExtensionName(fileName);
        if (!"XLSX".equals(extraFileName.toUpperCase())) {
            throw new BusinessException("文件格式不正确,必须为2007版的excel文件");
        }

        wb = new XSSFWorkbook(fileName);
    }

             就是怎么获取这个filename？我是从jsp页面上传的文件