如何使用Java/Android正确测量下载速度

Question

我正在尝试在我的Android应用程序中执行一个AsyncTask类，以分析下载和上传的网络连接速度。我现在正在下载部分，但我没有得到我期望的结果。我正在一个Wifi网络上进行测试，这个网络的速度一直保持在15Mbps以下，但是从我的应用程序中得到的结果更差不多在1pbs左右。当我在设备上运行速度测试apk时，我测试的速度大约为3.5Mbps。该功能起作用，似乎只有它的一半速度。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); 
    } 

实施例输出

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 

预先感谢您的帮助。如果有更好的方法，请告诉我。

Answer 1

继我的意见，在这里是如何从流

//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); 
} 

这样做是它读成一个byte []缓冲区中读取几个字节，并返回读取的字节量的例子。这又被写入到OutputStream中，指定要写入的字节数量。

ByteArrayOutputStream也有一个toByteArray行为相似。

另外，您也可以直接写入文件，如果你考虑到文件操作写比读功能显著快：

// 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，如果你真的只关心下载速度，它不是强制性的写入文件或任何地方，这将是足够的：

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