CommonsMultipartFile 转为 File 类型

@Override
    public InputStream getInputStream() throws IOException {
        if (!isAvailable()) {
            throw new IllegalStateException("File has been moved - cannot be read again");
        }
        InputStream inputStream = this.fileItem.getInputStream();
        return (inputStream != null ? inputStream : StreamUtils.emptyInput());
    }

CommonsMultipartFile shopImg = null; //注意啊，这里你要传的CommonsMultipartFile 参数自己通过commfile去接收就行

inputStreamToFile(commfile.getInputStream(), file);  //getInputStream是CommonsMultipartFile的方法（文件转化）

private static void inputStreamToFile(InputStream ins,File file) {
        FileOutputStream os = null;
        try {
            os = new FileOutputStream(file);
            int bytesRead = 0;
            byte[] buffer = new byte[1024];
            while ((bytesRead = ins.read(buffer)) != -1) {
                os.write(buffer, 0, bytesRead);
            }
        } catch (Exception e) {
            throw new RuntimeException("调用inputStreamToFile异常" +e.getMessage());
        }finally {
            try {
                if (os != null) {
                    os.close();
                }
                if (ins != null) {
                    ins.close();
                }
            } catch (Exception e) {
                throw new RuntimeException("调用inputStreamToFile异常" +e.getMessage());
            }
        }
    }