Java: How to download chunked content correctly?

问题

I have to download file which HTTP response is "Transfer-Encoding: Chunked", because of what I can't to «getContentLength» to allocate new bytes buffer for DataInputStream. Can you advice me how to do it correctly?

Code example is very simple:

try
{
       dCon = (HttpURLConnection) new URL(torrentFileDownloadLink.absUrl("href")).openConnection();
       dCon.setRequestProperty("Cookie", "session=" + cookies.get("session"));
       dCon.setInstanceFollowRedirects(false);
       dCon.setRequestMethod("GET");
       dCon.setConnectTimeout(120000);
       dCon.setReadTimeout(120000);

      // byte[] downloadedFile == ???

      DataInputStream br = new DataInputStream((dCon.getInputStream()));
      br.readFully(downloadedFile);
      System.out.println(downloadedFile);

} catch(IOException ex) { Logger.getLogger(WhatCDWork.class.getName()).log(Level.SEVERE, null, ex); }

回答1:

The HttpURLConnection will take care of all the de-chunking for you. Just copy the bytes until end of stream:

byte[] buffer = new  byte[8192];
int count;
while ((count = in.read( buffer)) > 0)
{
    out.write(buffer, 0, count);
}
out.close();
in.close();

where out is whatever OutputStream you want to save the data to. Could even be a ByteArrayOutputStream if you really need it in memory, although this isn't advisable as not everything fits into memory.

NB GET is already the default request method. You don't have to set it.

来源：https://stackoverflow.com/questions/5737945/java-how-to-download-chunked-content-correctly