一、引入依赖包

 <!-- 文件上传工具类 --><dependency><groupId>commons-fileupload</groupId><artifactId>commons-fileupload</artifactId><version>1.3.3</version></dependency>

二、本地文件转为MultipartFile

/*** 本地文件转为MultipartFile** @param picPath* @return*/public static MultipartFile pathToMultipartFile(String picPath) throws Exception{FileItem fileItem = createFileItem(picPath);MultipartFile mfile = new CommonsMultipartFile(fileItem);return mfile;}/*** 将file转换成fileItem** @param filePath* @return*/public static FileItem createFileItem(String filePath) throws Exception{FileItemFactory factory = new DiskFileItemFactory(16, null);String textFieldName = "textField";FileItem item = factory.createItem(textFieldName, "text/plain", true, "MyFileName");File newfile = new File(filePath);int bytesRead = 0;byte[] buffer = new byte[8192];FileInputStream fis = null;OutputStream os = null;try {fis = new FileInputStream(newfile);os = item.getOutputStream();while ((bytesRead = fis.read(buffer, 0, 8192)) != -1) {os.write(buffer, 0, bytesRead);}} catch (IOException e) {System.out.println("createFileItem:文件转换异常！");throw e;} finally {try {if (null != os){os.close();}if (null != fis){fis.close();}} catch (IOException e) {System.out.println("createFileItem:关流异常！");throw e;}}return item;}

三、图片地址转 MultipartFile

/*** 图片地址转 MultipartFile* @param url* @return*/public static MultipartFile uploadImgUrlToMultipartFile(String url) {byte[] bytes = downloadPicture(url);//url.substring(url.lastIndexOf(".")); 此处为获取扩展名，根据情况修改String name = "imageFile" + url.substring(url.lastIndexOf("."));MultipartFile multipartFile = getMultipartFile(name, bytes);return multipartFile;}//二进制文件转换MultipartFilepublic 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;}//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;}