Java File URI error ?

Question

I need to get a file object online, and I know the file is located at : http://nmjava.com/Dir_App_IDs/Dir_GlassPaneDemo/GlassPaneDemo_2010_04_06_15_00_SNGRGLJAMX

If I paste it into my browser's url, I'll be able to download this file, now I'm trying to get it with Java, my code looks like this :

String File_Url="http://nmjava.com/Dir_App_IDs/Dir_GlassPaneDemo/GlassPaneDemo_2010_04_06_15_00_SNGRGLJAMX";
Object myObject=Get_Online_File(new URI(File_Url));

Object Get_Online_File(URI File_Uri) throws IOException
{
  return readObject(new ObjectInputStream(new FileInputStream(new File(File_Uri))));
}

public static synchronized Object readObject(ObjectInput in) throws IOException
{
  Object o;
  ......
  return o;
}

But I got the following error message :

java.lang.IllegalArgumentException: URI scheme is not "file"
        at java.io.File.<init>(File.java:366)

Why ? How to fix it ?

Frank

Answer 1

Try "file://nmjava.com/Dir_App_IDs/Dir_GlassPaneDemo/GlassPaneDemo_2010_04_06_15_00_SNGRGLJAMX"

Answer 2

I'm not sure if FileInputStream is designed for reading over the internet .. try new URL(File_Uri).openConnection().getInputStream()

Answer 3

Don't use FileInputStream for this purpose. Create URL, then get input stream and read data from it.

URL url = new URL (fileUrl);
InputStream inputStream = url.openStream ();
readData (inputStream);

For reading data I recommend you to use Commons IO library (especially if there are 2 or more places where you work with streams, it'll save your time and make your code more expressive):

private byte[] readData (InputStream in) {
   try {
      return IOUtils.toByteArray (in);
   } finally {
      IOUtils.closeQuietly(in);
   }
}

---

You also operate in your code with Object streams (like ObjectInputStream). But that stream should be used only to read serialized java object and it's not the case as I understand from the description (if it would be a serialized object then your browser hadn't opened that file).

Answer 4

I got inspired, the correct answer is :

Object myObject=Get_Online_File(new URL(File_Url));

Object Get_Online_File(URL File_Url) throws IOException
{
  return readObject(new ObjectInputStream(File_Url.openConnection().getInputStream()));
  // or readObject(new ObjectInputStream(File_Url.openStream()));
}