文件流复制

 @PostMapping("/upload")
public void  uploadFile(MultipartFile file){
    
    
   
        InputStream streamOne;
        InputStream streamTwo;
        InputStream inputStream;
        try {
    
    
            inputStream = file.getInputStream();
        } catch (IOException e) {
    
    
            log.error("Get file stream exception", e);
           throw new IllegalArgumentException("文件上传失败");
        }
        ByteArrayOutputStream baos = copyInputStream(inputStream);
        streamOne = new ByteArrayInputStream(baos.toByteArray());
        streamTwo = new ByteArrayInputStream(baos.toByteArray());
        //业务处理
        //....
}
    

      /**
     * 流复制
     */
    private static ByteArrayOutputStream copyInputStream(InputStream input) {
    
    
        try {
    
    
            //spring 计时器
            Stopwatch stopWatch = Stopwatch.createStarted();
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            // 定义一个缓存数组，临时存放读取的数组
            byte[] buffer = new byte[4096];
            int length;
            while ((length = input.read(buffer)) > -1) {
    
    
                baos.write(buffer, 0, length);
            }
            baos.flush();
            stopWatch.stop();
            log.info("流拷贝，总耗时[{}] ms", stopWatch.elapsed(TimeUnit.MILLISECONDS));
            return baos;
        } catch (IOException e) {
    
    
            log.error("Stream copy exception", e);
        }

        throw new IllegalArgumentException("文件上传失败");
    }
    }