java 实现断点续传

/**
 * 下载服务器已存在的文件,支持断点续传
 *
 * @param request
 *            请求对象
 * @param response
 *            响应对象
 * @param path
 *            文件路径(绝对)
 */
public static void download(HttpServletRequest request, HttpServletResponse response, String  path) {
    System.out.println("下载文件路径：" + path);
    InputStream inputStream = null;
    OutputStream bufferOut = null;
    File proposeFile=new File(path);
    try {
        // 设置响应报头
        long fSize = proposeFile.length();
        response.setContentType("application/x-download");
        // Content-Disposition: attachment; filename=WebGoat-OWASP_Developer-5.2.zip
        response.addHeader("Content-Disposition", "attachment; filename=" + URLEncoder.encode(proposeFile.getName(), "utf-8"));
        // Accept-Ranges: bytes
        response.setHeader("Accept-Ranges", "bytes");
        long pos = 0, last = fSize - 1, sum = 0;//pos开始读取位置;  last最后读取位置;  sum记录总共已经读取了多少字节
        if (null != request.getHeader("Range")) {
            // 断点续传
            response.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT);
            try {
                // 情景一：RANGE: bytes=2000070- 情景二：RANGE: bytes=2000070-2000970
                String numRang = request.getHeader("Range").replaceAll("bytes=", "");
                String[] strRange = numRang.split("-");
                if (strRange.length == 2) {
                    pos = Long.parseLong(strRange[0].trim());
                    last = Long.parseLong(strRange[1].trim());
                } else {
                    pos = Long.parseLong(numRang.replaceAll("-", "").trim());
                }
            } catch (NumberFormatException e) {
                System.out.println(request.getHeader("Range") + " is not Number!");
                pos = 0;
            }
        }
        long rangLength = last - pos + 1;// 总共需要读取的字节
        // Content-Range: bytes 10-1033/304974592
        String contentRange = new StringBuffer("bytes ").append(pos).append("-").append(last).append("/").append(fSize).toString();
        response.setHeader("Content-Range", contentRange);
        // Content-Length: 1024
        response.addHeader("Content-Length", String.valueOf(rangLength));

        // 跳过已经下载的部分，进行后续下载
        bufferOut = new BufferedOutputStream(response.getOutputStream());
        inputStream = new BufferedInputStream(new FileInputStream(proposeFile));
        inputStream.skip(pos);
        byte[] buffer = new byte[1024];
        int length = 0;
        while (sum < rangLength) {
            length = inputStream.read(buffer, 0, ((rangLength - sum) <= buffer.length ? ((int) (rangLength - sum)) : buffer.length));
            sum = sum + length;
            bufferOut.write(buffer, 0, length);
        }
    } catch (Throwable e) {
        if (e instanceof ClientAbortException) {
            // 浏览器点击取消
            System.out.println("用户取消下载!");

        } else {
            System.out.println("下载文件失败....!");

        }
        e.printStackTrace();
    } finally {
        try {
            if (bufferOut != null) {
                bufferOut.close();
            }
            if (inputStream != null) {
                inputStream.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

分  槽的方式：成功

https://www.cnblogs.com/surpassme/p/11832438.html 

dockers for windows 

https://blog.csdn.net/zhuiyisinian/article/details/88700889

 

 

 

https://www.jianshu.com/p/3f9e2368e546

 

 

https://blog.csdn.net/qq_43090889/article/details/96007729