如何使用Java / Android正确衡量下载速度

我正在尝试在我的Android应用程序中执行AsyncTask类,该类分析下载和上传的网络连接速度.我现在正在下载部分,但没有得到预期的结果.我正在一个Wifi网络上进行测试,该网络始终保持15Mbps的降速/升速,但是,从我的应用程序获得的结果几乎只有1Mpbs.当我在要测试的设备上运行速度测试apk时,速度约为3.5Mbps.该功能起作用,似乎只是速度的一半.以下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);
   }

输出示例

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

先谢谢您的帮助.如果有更好的方法,请告诉我.

解决方法:

在我的评论之后,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);
}

它的作用是将其读入byte []缓冲区,并返回读取的字节数.依次将其写入到OutputStream,指定要写入的字节数.

ByteArrayOutputStream还具有行为类似的toByteArray.

另外,如果您认为写入文件的操作比读取功能要快得多,那么也可以直接写入文件：

// 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,则不必强制写入文件或任何位置,这就足够了：

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

标签：performance,download,bandwidth,java,android
来源： https://codeday.me/bug/20191030/1967067.html