文件上传工具类（重命名，以及判断类型）

public class FileUploadUtil {
public static final List<String> ALLOW_TYPES = Arrays.asList(
"image/jpg","image/jpeg","image/png","image/gif"
);
//文件重命名
public static String rename(String fileName){
int i = fileName.lastIndexOf(".");
String str = fileName.substring(i);
return new Date().getTime()+""+ new Random().nextInt(99999999) +str;
}
//校验文件类型是否是被允许的
public static boolean allowUpload(String postfix){
return ALLOW_TYPES.contains(postfix);
}
}

//自己写的一个使用例子
private void uploadGoodsImg(
MultipartFile[] imageFiles,
String goodsId,
String realPath,
String resourcePath,
String type
) throws IOException {
if (imageFiles != null) {
for (int i = 0; i < imageFiles.length; i++) {
MultipartFile imageFile = imageFiles[i];
//先检验文件类型是否被允许
if (FileUploadUtil.allowUpload(imageFile.getContentType())) {
//                获得文件名称后重命名
String fileName = goodsId + FileUploadUtil.rename(imageFile.getOriginalFilename());
File file = new File(realPath + resourcePath + fileName);
imageFile.transferTo(file);
//缩略图
Thumbnails.of(file)
.size(160, 160)
.keepAspectRatio(false)
.outputFormat("jpg")
.toFile(new File(realPath + resourcePath, fileName + "_160x160.jpg"));
String imgUrl = resourcePath + fileName;
GoodsImg goodsImg = new GoodsImg();
goodsImg.setId(UUID.randomUUID().toString());
goodsImg.setGoodsId(goodsId);
goodsImg.setUrl(imgUrl);
goodsImg.setSort(i + 1);
goodsImgDao.insert(goodsImg);
}
else {
throw new RuntimeException("文件类型不合法,只能是 jpg、gif、png、jpeg 类型！");
}
}
} else if(type.equals("add")) {
GoodsImg goodsImg = new GoodsImg();
goodsImg.setId(UUID.randomUUID().toString());
goodsImg.setGoodsId(goodsId);
goodsImg.setUrl(null);
goodsImg.setSort(1);
goodsImgDao.insert(goodsImg);
}
}