Android Eclipse Emulator and FTP

[Paul Kinzelman]

I'm interested in doing just a simple FTP 'get' in my app. It works fine on the Palm Pre and WPF/C# and windows, but not the Android at least on the emulator and I can't find any examples from the searching I've done. I tried a simple:

StringBuilder response = new StringBuilder();
  URLConnection ftpConn;
  try {
  URL netUrl = new URL("ftp://tgftp.nws.noaa.gov/data/observations/metar/stations/KABQ.TXT");
  ftpConn = netUrl.openConnection();
  BufferedInputStream bufRd = new BufferedInputStream(ftpConn.getInputStream());
  int temp;
  while ((temp = bufRd.read()) != -1) {
      response.append(temp);
  }
  bufRd.close();
  } catch (Exception e) {
      return "Failure";
  }

but it gets an exception on getInputStream: Unable to connect to server: Unable to configure data port

And I know internet access works because I can do an http protocol request. I have the magical incantation in the manifest file to allow network access:
<uses-permission android:name="android.permission.INTERNET" />

Also, there must be a more intelligent way to pull the data out of the stream buffer than byte-by-byte, isn't there? I can't find that either.

[Ulf Dittmer]

I wouldn't rely on the URL ftp: scheme to work. The Apache Commons Net library has FTP client classes built in, and it works just fine on Android.

[Paul Kinzelman]

Too bad, the ftp URL scheme works fine on webOS and WPF/C#.

Could you please be a bit more specific about how to do what you suggest?
And how to make it work in the Eclipse/Emulator environment?

Would I need to refer a JAR library or something?

I tried the FTPClient library here: http://androiddev.orkitra.com/?p=139
but I can't get it to work either, says "NoClassDefFoundError" as though the library
is not available on the Emulator, but is available on Eclipse - the references get
resolved properly. It there some magical incantation I need in the AndroidManifest
file or something?

Thanks!

[Paul Kinzelman]

Whew! I finally got it going.

After fixing the library access (Project | Properties | Java Build Path | Libraries | Add JARs...) I fiddled with the calls until it started working. Here's the sequence of my FTPClient calls. It wouldn't work until I set it in passive mode.

      mFTPClient = new FTPClient();
      mFTPClient.connect("tgftp.nws.noaa.gov");      
      mFTPClient.login("anonymous","nobody");
      mFTPClient.enterLocalPassiveMode();
      mFTPClient.changeWorkingDirectory("/data/forecasts/taf/stations");
      InputStream inStream = mFTPClient.retrieveFileStream("KABQ.TXT");
      InputStreamReader isr = new InputStreamReader(inStream, "UTF8");