Method rangeDownloadResponse

src/main/java/cms/utils/WebUtil.java:346–422

断点续传流式下载 适合大文件(以流的形式向页面输出数据) @param physicalPath 完整路径(路径+文件名称) @param fileName 文件名称 @param request 响应信息 @return

(String physicalPath, String fileName,String rangeHeader, HttpServletRequest request,HttpServletResponse response)

	 * @return
	*/
	public static ResponseEntity<StreamingResponseBody> rangeDownloadResponse(String physicalPath, String fileName,String rangeHeader, HttpServletRequest request,HttpServletResponse response) {
		
		Path filePath = Paths.get(physicalPath);
		
        long fileLength = 0L;
        try (FileChannel fileChannel = FileChannel.open(filePath)) {
            fileLength = fileChannel.size();
        } catch (IOException e) {
            if (logger.isErrorEnabled()) {
                logger.error("读取文件长度错误"+physicalPath,e);
            }
            return ResponseEntity.badRequest().build();
        }

        
        long rangeStart = 0L;
        long rangeEnd = fileLength;
        
        
        if (rangeHeader != null) {
            //example: bytes=0-1023 表示从0取到1023，长度为1024
            String[] ranges = rangeHeader.substring("bytes=".length()).split("-");
            rangeStart = Long.parseLong(ranges[0]);
            if (ranges.length > 1) {
                rangeEnd = Long.parseLong(ranges[1]) + 1;
            }
        }
        final long skip = rangeStart;
        final long contentLength = rangeEnd - rangeStart;
		
		
		StreamingResponseBody streamingResponseBody = new StreamingResponseBody() {
	        @Override
	        public void writeTo(OutputStream outputStream) throws IOException { 
	        	try( InputStream inputStream = Files.newInputStream(filePath);
            			BufferedInputStream bufferedInputStream = new BufferedInputStream(inputStream);	
            		){
            		
            		bufferedInputStream.skip(skip);
	                byte[] bytes = new byte[1024];
	                long readSum = 0;
	                int readCount = 0;
	                while ((readCount = bufferedInputStream.read(bytes)) != -1) {
	                    if (readSum + readCount > contentLength) {
	                        outputStream.write(bytes, 0, (int) (contentLength - readSum));
	                    } else {
	                        outputStream.write(bytes, 0, readCount);
	                    }
	                    readSum = readSum + readCount;
	                }
	                outputStream.flush();
	                
            	}
			   
	        }
	    };
	   
	    String header = request.getHeader("User-Agent").toUpperCase();