通过url下载图片并转成MultipartFile类型

某业务图片不能直接上传到自己服务器，只能上传到第三方并返回图片url，但图片源文件自己也需要保存，所以需要通过url下载图片并上传至自己服务器

public static MultipartFile uploadImgUrlToMultipartFile(String url) {

        byte[] bytes = downloadPicture(url);
        String name = "imageFile" + url.substring(url.lastIndexOf("."));
        MultipartFile multipartFile = getMultipartFile(name, bytes);
        return multipartFile;
    }

先将图片通过url下载转为二进制

    //获取图片二进制
    private static byte[] downloadPicture(String url) {
        URL urlConnection = null;
        HttpURLConnection httpURLConnection = null;
        try {
            urlConnection = new URL(url);
            httpURLConnection = (HttpURLConnection) urlConnection.openConnection();
            InputStream in = httpURLConnection.getInputStream();
            byte[] buffer = new byte[1024];
            int len = 0;
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            while ((len = in.read(buffer)) != -1) {
                out.write(buffer, 0, len);
            }
            in.close();
            out.close();
            return out.toByteArray();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            httpURLConnection.disconnect();
        }
        return null;
    }

二进制文件转换MultipartFile

//二进制文件转换MultipartFile
    public static MultipartFile getMultipartFile(String name, byte[] bytes) {
        MultipartFile mfile = null;
        ByteArrayInputStream in = null;
        try {
            in = new ByteArrayInputStream(bytes);
            FileItemFactory factory = new DiskFileItemFactory(16, null);
            FileItem fileItem = factory.createItem("mainFile", "text/plain", false, name);
            IOUtils.copy(new ByteArrayInputStream(bytes), fileItem.getOutputStream());
            mfile = new CommonsMultipartFile(fileItem);
            in.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return mfile;
    }