我正在尝试在我的 Android 应用程序中执行一个 AsyncTask 类，该类分析用于下载和上传的网络连接速度。我现在正在处理下载部分，但没有得到预期的结果。我在 Wifi 网络上进行测试，该网络的下行/上行速度始终为 15Mbps，但是，我从我的应用程序中获得的结果几乎只有 1Mbps。当我在我正在测试的设备上运行速度测试 apk 时，速度大约为 3.5Mbps。该功能有效，似乎速度只有应有的一半。下面的代码应该产生准确的结果吗？

try {
           String DownloadUrl = "http://ipv4.download.thinkbroadband.com:8080/5MB.zip";
           String fileName = "testfile.bin";
       
       
           File dir = new File (context.getFilesDir() + "/temp/");
           if(dir.exists()==false) {
                dir.mkdirs();
           }

           URL url = new URL(DownloadUrl); //you can write here any link
           File file = new File(context.getFilesDir() + "/temp/" + fileName);
           

           long startTime = System.currentTimeMillis();
           Log.d("DownloadManager", "download begining: " + startTime);
           Log.d("DownloadManager", "download url:" + url);
           Log.d("DownloadManager", "downloaded file name:" + fileName);
           
           /* Open a connection to that URL. */
           URLConnection ucon = url.openConnection();

           //Define InputStreams to read from the URLConnection.
           InputStream is = ucon.getInputStream();
           BufferedInputStream bis = new BufferedInputStream(is);

           //Read bytes to the Buffer until there is nothing more to read(-1).  
           ByteArrayBuffer baf = new ByteArrayBuffer(1024);
           int current = 0;
           while ((current = bis.read()) != -1) {
              baf.append((byte) current);
           }
           long endTime = System.currentTimeMillis(); //maybe

           /* Convert the Bytes read to a String. */
           FileOutputStream fos = new FileOutputStream(file);
           fos.write(baf.toByteArray());
           fos.flush();
           fos.close();
           
          File done = new File(context.getFilesDir() + "/temp/" + fileName);
          Log.d("DownloadManager", "Location being searched: "+ context.getFilesDir() + "/temp/" + fileName);
          double size = done.length();
          if(done.exists()) {
              done.delete();
          }

          Log.d("DownloadManager", "download ended: " + ((endTime - startTime) / 1000) + " secs");
          double rate = (((size / 1024) / ((endTime - startTime) / 1000)) * 8);
          rate = Math.round( rate * 100.0 ) / 100.0;
          String ratevalue;
          if(rate > 1000)
             ratevalue = String.valueOf(rate / 1024).concat(" Mbps");
          else
             ratevalue = String.valueOf(rate).concat(" Kbps"); 
          Log.d("DownloadManager", "download speed: "+ratevalue);       
   } catch (IOException e) {
       Log.d("DownloadManager", "Error: " + e);
   }

示例输出

10-08 15:09:52.658: D/DownloadManager(13714): download ended: 70 secs
10-08 15:09:52.662: D/DownloadManager(13714): download speed: 585.14 Kbps

在此先感谢您的帮助。如果有更好的方法，请告诉我。

最佳答案

根据我的评论，这是一个如何从流中读取几个字节的示例

//Define InputStreams to read from the URLConnection.
InputStream is = ucon.getInputStream();
BufferedInputStream bis = new BufferedInputStream(is);

//I usually use a ByteArrayOutputStream, as it is more common.
ByteArrayOutputStream baos = new ByteArrayOutputStream();
int red = 0;
// This size can be changed
byte[] buf = new byte[1024];
while ((red = bis.read(buf)) != -1) {
    baos.write(buf, 0, red);
}

它的作用是读入 byte[] 缓冲区，并返回读取的字节数。这又被写入 OutputStream，指定要写入的字节数。

ByteArrayOutputStream 也有一个行为类似的 toByteArray。

或者，您也可以直接写入文件，如果您认为写入文件操作明显快于读取函数:

// Simply start by defining the fileoutputstream
FileOutputStream fos = new FileOutputStream(file);
int red = 0;
// This size can be changed
byte[] buf = new byte[1024];
while ((red = bis.read(buf)) != -1) {
    // And directly write to it.
    fos.write(buf, 0, red);
}
long endTime = System.currentTimeMillis(); //maybe
// Flush after, as this may trigger a commit to disk.
fos.flush();
fos.close();

此外，如果您真的只关心下载速度，则不必写入文件或任何地方，这就足够了:

long size = 0;
byte[] buf = new byte[1024];
while ((red = bis.read(buf)) != -1) {
    size += red;
}

关于java - 如何使用 Java/Android 正确测量下载速度，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/19258254/