java如何在sd上写入文件时获得文件大小？

Question

请帮帮我。我需要得到完整的文件大小，并且已经写入while循环。我需要这个来设置进度条的进度。 这是我的代码：

            try {
            URL u = new URL(imgUrl);
              InputStream is = u.openStream();

              DataInputStream dis = new DataInputStream(is);

              byte[] buffer = new byte[1024];
              int length;
              File root = new File(Environment.getExternalStorageDirectory()
                      + File.separator + "saved" + File.separator);
                    root.mkdirs();
                    String name = "" + System.currentTimeMillis() + ".jpg";
                    File sdImageMainDirectory = new File(root, name);
                    Uri outputFileUri = Uri.fromFile(sdImageMainDirectory);
                    OutputStream output = new FileOutputStream(sdImageMainDirectory);


            while ((length = dis.read(buffer))>0) {
                  output.write(buffer, 0, length);
            }

            } catch (MalformedURLException mue) {
                  Log.e("SYNC getUpdate", "malformed url error", mue);
                } catch (IOException ioe) {
                  Log.e("SYNC getUpdate", "io error", ioe);
                } catch (SecurityException se) {
                  Log.e("SYNC getUpdate", "security error", se);
                }

Answer 1

如果您想获得已经写入的字节数，请使用以下方法：

在while循环之前添加一个名为writtenBytes的变量：

long writtenBytes = 0L;

然后，在while循环中，添加以下代码：

while ((length = dis.read(buffer))>0) {
    output.write(buffer, 0, length);
    writtenBytes += length;
}

要在下载文件之前获得文件大小，您必须将下载代码更改为：

URL url = new URL(imgUrl);
URLConnection connection = url.openConnection();
connection.connect();

int fileLength = connection.getContentLength();
InputStream inputStream = url.openStream();

DataInputStream dis = new DataInputStream(is);