Name: nt126004 Date: 02/11/2002


FULL PRODUCT VERSION :
java version "1.4.0-rc"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-rc-b91)
Java Hotspot(TM) Client VM (build 1.4.0-rc-b91, mixed mode)


FULL OPERATING SYSTEM VERSION :

Windows 98 [Version 4.10.2222]



A DESCRIPTION OF THE PROBLEM :

I noticed that File now support some new methods for
transformation into URL and URI, however File itself does
not support the opposite direction, so I would like to
propose that you add a constructor for URL to complement
the newly added URI constructor.

I think this is important because there are many types that
represent addresses (URI, URL, File) and there lacks a
subtype relation between URL and URI.

I'd also be nice with an access interface so that the
system can attempt to construct a Channel for a URI; this
way one wouldn't have to use these constructors oneself;
check this out:

public interface Access {
  ReadableByteChannel read() throws IOException;
  WritableByteChannel write() throws IOException;
}

URI, URL and File can then implement the Access type and
users can easily get byte access to resources. This isn't
perfect, but I think it's better.

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I'd like to be able to do this:

  URL a = new URL("http://www.javasoft.com/x");
  File b = new File(a);

can't be done right now. I could use URI but I want File to do the work, not
me. So add a constructor in File that accepts a URL to complement the existing
URI constructor -- and this is important since the URL class does not inherit
URI class :/

In addition this would be nice:

  public interface Access {
    ReadableByteChannel read() throws IOException;
    WritableByteChannel write() throws IOException;
  }

Then implement this in URI, URL and File and I would be able to do:

  URL x = new URL("http://www.test.com/x");
  ReadableByteChannel rchan = x.read(); // no can do right now

I think this improves usability a great deal, but I have no particular prefs
regarding the way access is provided, as long as it is works on all these three
types: URI, URL, File, in the situation where it is possible to retrieve an
entity-body -- otherwise it would just throw an IOException.

Please note that although it is possible to make progress without this
improvement, it is not possible to use it for somethings without a separate
wrapper class or using JNDI but I'm not even sure JNDI supports "uniform
access" -- AFAIK it uses URL, File etc. objects and so I would have to have
prior knowledge of these types to use it when all I want is to get a
ByteChannel.
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(Review ID: 139039)
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