public String uploadFile(String firstPath, String prePath, MultipartFile[] file) throws IOException {
    String finalPath = "";
    for (int i = 0; i < file.length; i++) {//迴圈存入檔案並組合路徑
MultipartFile thisfile = file[i];
        String fileName = thisfile.getOriginalFilename();//得到檔名稱
if (fileName != "" 
 
&& !thisfile.isEmpty()) {
            if (i + 1 < file.length) finalPath = finalPath + firstPath + fileName + "||";//判斷是否要加分隔符，如果沒有檔案則返回null
else if (!thisfile.isEmpty()) finalPath = finalPath + firstPath + fileName;
            String accessPath = prePath + "/" + fileName;
            File dest = new 
 
File(accessPath);
            if (!dest.getParentFile().exists()) {// 檢測是否存在目錄
dest.getParentFile().mkdirs();
            }
            thisfile.transferTo(dest);//寫入檔案
} else return finalPath;
    }
    return finalPath;
}