java中如何通过URL转MultipartFile呢?

/**
 * URL -> MultipartFile
 *
 * @param fileUrl
 * @param fileName
 * @return
 */
public static MultipartFile urlToMultipartFile(String fileUrl, String fileName) {
    File file = null;
    MultipartFile multipartFile = null;
    try {
        HttpURLConnection httpUrl = (HttpURLConnection) new URL(fileUrl).openConnection();
        httpUrl.connect();
        file = inputStreamToFile(httpUrl.getInputStream(), fileName);
        System.out.println(String.format("URL -> file", file));

        multipartFile = fileToMultipartFile(file);
        System.out.println(String.format("file -> MultipartFile", multipartFile));
        httpUrl.disconnect();
    } catch (Exception e) {
        e.printStackTrace();
    }
    return multipartFile;
}

/**
 * InputStream -> File
 *
 * @param ins
 * @param name
 * @return
 * @throws Exception
 */
public static File inputStreamToFile(InputStream ins, String name) throws Exception {
    File file = new File(System.getProperty("java.io.tmpdir") + File.separator + name);
    OutputStream os = new FileOutputStream(file);
    int bytesRead;
    int len = 8192;
    byte[] buffer = new byte[len];
    while ((bytesRead = ins.read(buffer, 0, len)) != -1) {
        os.write(buffer, 0, bytesRead);
    }
    os.close();
    ins.close();
    return file;
}

/**
 * File -> MultipartFile
 *
 * @param file
 * @return
 */
public static MultipartFile fileToMultipartFile(File file) {
    FileItemFactory factory = new DiskFileItemFactory(16, null);
    FileItem item = factory.createItem(file.getName(), "text/plain", true, file.getName());
    int bytesRead = 0;
    byte[] buffer = new byte[8192];
    try {
        FileInputStream fis = new FileInputStream(file);
        OutputStream os = item.getOutputStream();
        while ((bytesRead = fis.read(buffer, 0, 8192)) != -1) {
            os.write(buffer, 0, bytesRead);
        }
        os.close();
        fis.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
    return new CommonsMultipartFile(item);
}