base64转MultipartFile并下载到本地

public class BASE64DecodeMultipartFile implements MultipartFile {
    private final byte[] imgContent;
    private final String header;
    public BASE64DecodeMultipartFile(byte[] imgContent, String header) {
        this.imgContent = imgContent;
        this.header = header.split(";")[0];
   }
   
    @Override
    public String getName() {
        return System.currentTimeMillis() + "." + header.split("/")[1];
   }
   
    @Override
    public String getOriginalFilename() {
        return System.currentTimeMillis() + "." + header.split("/")[1];
   }
   
    @Override
    public String getContentType() {
        return header.split(":")[1];
   }
   
    @Override
    public boolean isEmpty() {
        return imgContent == null || imgContent.length == 0;
   }
   
    @Override
    public long getSize() {
        return imgContent.length;
   }
   
    @Override
    public byte[] getBytes() throws IOException {
        return imgContent;
   }
   
    @Override
    public InputStream getInputStream() throws IOException {
        return new ByteArrayInputStream(imgContent);
   }
   
    @Override
    public void transferTo(File dest) throws IOException, IllegalStateException {
        new FileOutputStream(dest).write(imgContent);
   }
}

public void udfForwardUpload(String base64Img) {
  		// 将base64转成MultipartFile文件
        MultipartFile image = null;
        StringBuilder base64 = new StringBuilder();
        if (!"".equals(base64Img)) {
            base64.append(base64Img);
            String[] baseStrs = base64.toString().split(",");
            BASE64Decoder decoder = new BASE64Decoder();
            byte[] imageByte = new byte[0];
            try {
                imageByte = decoder.decodeBuffer(baseStrs[1]);
           } catch (IOException e) {
                e.printStackTrace();
           }
            for (int j = 0; j < imageByte.length; ++j) {
                if (imageByte[j] < 0) {
                    imageByte[j] += 256;
               }
           }
            image = new BASE64DecodeMultipartFile(imageByte, baseStrs[0]);
            // 将MultipartFile文件下载到本地
            String fileName = image.getOriginalFilename();
            File dest = new File(new File("F:\\test").getAbsolutePath()+ "/" + fileName);
            if (!dest.getParentFile().exists()) {
                dest.getParentFile().mkdirs();
           }
            try {
             	// 保存文件
                image.transferTo(dest);
           } catch (Exception e) {
                e.printStackTrace();
           }
       }
   }