base64图片流转为MultipartFile文件 java后台

一时失言乱红尘 2022-05-19 09:49 526阅读 0赞

MultipartFile是spring框架中的接口，需要自己写一个实现类。代码如下：

public class BASE64DecodedMultipartFile implements MultipartFile {
    
        private final byte[] imgContent;
        private final String header;
    
        public BASE64DecodedMultipartFile(byte[] imgContent, String header) {
            this.imgContent = imgContent;
            this.header = header.split(";")[0];
        }
    
        @Override
        public String getName() {
            // TODO - implementation depends on your requirements
            return System.currentTimeMillis() + Math.random() + "." + header.split("/")[1];
        }
    
        @Override
        public String getOriginalFilename() {
            // TODO - implementation depends on your requirements
            return System.currentTimeMillis() + (int)Math.random() * 10000 + "." + header.split("/")[1];
        }
    
        @Override
        public String getContentType() {
            // TODO - implementation depends on your requirements
            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 static MultipartFile base64ToMultipart(String base64) {
          try {
            String[] baseStrs = base64.split(",");
    
            BASE64Decoder decoder = new BASE64Decoder();
            byte[] b = new byte[0];
            b = decoder.decodeBuffer(baseStrs[1]);
    
            for(int i = 0; i < b.length; ++i) {
                if (b[i] < 0) {
                    b[i] += 256;
                }
            }
            return new BASE64DecodedMultipartFile(b, baseStrs[0]);
          } catch (IOException e) {
            e.printStackTrace();
            return null;
          }
       }
    
    }

用法：

//"data:image/png;base64," 这个头规则加到base64上后，就可以直接显示到网页上了
    String avatar = "data:image/png;base64," + "base64图片字符串";
    MultipartFile file = BASE64DecodedMultipartFile.base64ToMultipart(avatar);
    //得到输入流
    InputStream inputStream = file.getInputStream();
    得到流就可以保存或传输了

有不对的地方欢迎留言。