HttpURLConnection java.io.FileNotFoundException

Question

The code below works great if I connect to what seems to be Apache servers, however when I try to connect to my .Net server it throws an error. I am guessing it is a header requirement, but I can not seem to get a successful response no matter what I try.

public String Download(String Url)
{
 String filepath=null;
 try {
  //set the download URL, a url that points to a file on the internet
  //this is the file to be downloaded
  URL url = new URL(Url);
  //create the new connection
  HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();

  //set up some things on the connection
  urlConnection.setRequestMethod("GET");
  urlConnection.setDoOutput(true); 
   //and connect!
  urlConnection.connect();
  //set the path where we want to save the file
  //in this case, going to save it on the root directory of the sd card.
  File SDCardRoot = Environment.getExternalStorageDirectory();
  //create a new file, specifying the path, and the filename
  //which we want to save the file as.

  String filename= "effortback.png";   // you can download to any type of file ex:.jpeg (image) ,.txt(text file),.mp3 (audio file)
  Log.i("Local filename:",""+filename);
  File file = new File(SDCardRoot + "/",filename);

  //=====================================
  if(file.createNewFile())
  {
   file.createNewFile();
  }
  //=====================================

  //this will be used to write the downloaded data into the file we created
  FileOutputStream fileOutput = new FileOutputStream(file);

  //this will be used in reading the data from the internet
  InputStream inputStream = urlConnection.getInputStream();

  //=====================================
  //this is the total size of the file
  int totalSize = urlConnection.getContentLength();
  //variable to store total downloaded bytes
  int downloadedSize = 0;
  //=====================================

  //create a buffer...
  byte[] buffer = new byte[2048];
  int bufferLength = 0; //used to store a temporary size of the buffer

  //now, read through the input buffer and write the contents to the file
  while ( (bufferLength = inputStream.read(buffer)) > 0 ) {
   //add the data in the buffer to the file in the file output stream (the file on the sd card
   fileOutput.write(buffer, 0, bufferLength);
   //add up the size so we know how much is downloaded
   downloadedSize += bufferLength;
   //this is where you would do something to report the prgress, like this maybe
   Log.i("Progress:","downloadedSize:"+downloadedSize+"totalSize:"+ totalSize) ;

  }
  //close the output stream when done
  fileOutput.close();
  if(downloadedSize==totalSize)   filepath=file.getPath();

 //catch some possible errors...
 } catch (MalformedURLException e) {
  e.printStackTrace();
  Log.i("URL-ERROR:",e.toString());
 } catch (IOException e) {
  filepath=null;
  e.printStackTrace();
  Log.i("IO-ERROR:",e.toString());
 }
 Log.i("filepath:"," "+filepath) ;

 return filepath;

}

Errors range from:

java.io.FileNotFoundException  //I always get this with either one of the below
   org.apache.harmony.luni.internal.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1061)

//or this one below
libcore.net.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionTmpl.java:186)

It seems that no matter what I try I can not get it to work. Again, it works if I try to download an image from Google or some other sites, but not all, but definitely not mine (.Net). What am I missing here? Please help.

Answer 1

You can get a FileNotFoundException from HttpUrlConnection (and OkHttpClient) if your server returns >= HTTPStatus.BAD_REQUEST (400). You should check the status code first to check what stream you need to read.

int status = connection.getResponseCode();

if(status >= HttpStatus.SC_BAD_REQUEST)
    in = connection.getErrorStream();
else
    in = connection.getInputStream();

HttpStatus deprecated. Latest syntax seems to be:

InputStream inputStream;
int status = urlConnection.getResponseCode();

if (status != HttpURLConnection.HTTP_OK)  {
    inputStream = urlConnection.getErrorStream();
}
else  {
    inputStream = urlConnection.getInputStream();
}

Answer 2

Had the same problem, solved like you said:

urlConnection.setDoOutput(false);

Note that you must set it to false because it's true by default.
Note that you must set it to false because Volley HurlStack was setting it to true.
Take care ;)

EDIT: I've just checked the code and by default it's false as @Abraham Philip said. But I had to set it to false because if I called getDoOutput() it was returning true. I found that Volley HurlStack was setting it to true. So, my conclusion is, setDoOutput to false and it will work.

package java.net;
public abstract class URLConnection {
...

    /**
     * Specifies whether this {@code URLConnection} allows sending data.
     */
    protected boolean doOutput;

...
    public boolean getDoOutput() {
        return doOutput;
    }

    public void setDoOutput(boolean newValue) {
        checkNotConnected();
        this.doOutput = newValue;
    }

Answer 3

I faced an issue, where executing a HEAD-Request threw a FileNotFoundException.
The reason is, that a response to a HEAD does not have a body and therefore a call to getInputStream throws a FileNotFoundException.

So if you are executing a HEAD, you should not try to get the InputStream.