java - 如何使用 bytes_downloaded 和 bytes_total Android/Java 测量下载速度

Question

如何使用两个值 1.总文件大小和 2.下载的总字节数来计算文件下载速度。

@Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        if (v.getId() == R.id.start_ed) {
            DownloadManager.Request request = new DownloadManager.Request(
                    Uri.parse(durl));
            request.setTitle("File Download");
            request.setDescription("file is being download");

            request.allowScanningByMediaScanner();
            request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
            String nof = URLUtil.guessFileName(durl, null,
                    MimeTypeMap.getFileExtensionFromUrl(durl));

            request.setDestinationInExternalPublicDir(
                    Environment.DIRECTORY_DOWNLOADS, nof);

            final DownloadManager downloadManager = (DownloadManager) MainActivity.this
                    .getSystemService(Context.DOWNLOAD_SERVICE);
            // long id = downloadManager.enqueue(request); //This is to get the
            // id of the download.
            final long download_id = downloadManager.enqueue(request);

            final ProgressBar mProgressBar = (ProgressBar) findViewById(R.id.progressBar1);
            final TextView current_tvm = (TextView) findViewById(R.id.current_tv);
            final TextView totl_tv = (TextView) findViewById(R.id.totalsize);
            new Thread(new Runnable() {

                @Override
                public void run() {

                    boolean downloading = true;

                    while (downloading) {

                        DownloadManager.Query q = new DownloadManager.Query();
                        q.setFilterById(download_id);

                        Cursor cursor = downloadManager.query(q);
                        cursor.moveToFirst();
                        final int bytes_downloaded = cursor.getInt(cursor
                                .getColumnIndex(DownloadManager.COLUMN_BYTES_DOWNLOADED_SO_FAR));
                        final int bytes_total = cursor.getInt(cursor
                                .getColumnIndex(DownloadManager.COLUMN_TOTAL_SIZE_BYTES));
                        if (cursor.getInt(cursor
                                .getColumnIndex(DownloadManager.COLUMN_STATUS)) == DownloadManager.STATUS_SUCCESSFUL) {
                            downloading = false;
                        }
                        final int dl_progress = (int) ((bytes_downloaded * 100l) / bytes_total);

                        runOnUiThread(new Runnable() {

                            @Override
                            public void run() {
                                // totl_tv.setText(bytes_total);
                                // current_tvm.setText(bytes_downloaded);
                                String i = android.text.format.Formatter
                                        .formatFileSize(MainActivity.this,
                                                bytes_downloaded);

                                System.out.println(i);
                                current_tvm.setText(i);
                                mProgressBar.setProgress((int) dl_progress);

                            }
                        });

                        // Log.d(Constants.MAIN_VIEW_ACTIVITY,
                        // statusMessage(cursor));
                        cursor.close();
                    }

                }
            }).start();

        }
    }

现在我有一个文件的两个值 bytes_downloaded 和 bytes_total，如何使用这两个值计算文件下载速度。提前致谢。

Answer 1

由于您已经有了 bytes_downloaded 值，因此您现在需要的只是时间维度。

bytes_downloaded / seconds taken = speed in bytes per second 

如果下载 10000 字节需要 10 秒，您的下载速度将为

10000 / 10 = 1000 bps = 8 kbps

计算速度不需要总文件大小，但是需要计算预计完成时间。