Velocity Reviews - Computer Hardware Reviews

Velocity Reviews > Newsgroups > Programming > Java > reading bytes with BufferedReader?

Reply
Thread Tools

reading bytes with BufferedReader?

 
 
R
Guest
Posts: n/a
 
      10-17-2006
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).

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?

 
Reply With Quote
 
 
 
 
bharat_sharma_5005@yahoo.co.in
Guest
Posts: n/a
 
      10-17-2006


On Oct 17, 3:24 am, "R" <(E-Mail Removed)> 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).
>
> 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?


 
Reply With Quote
 
 
 
 
Tom Forsmo
Guest
Posts: n/a
 
      10-17-2006
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
 
Reply With Quote
 
EJP
Guest
Posts: n/a
 
      10-18-2006
Tom Forsmo wrote:

> 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


Well you can't even do that for a start, you can't put an InputStream on
top of a Reader.

In the OP's circumstance I would just use the dreaded
DataInputStream.readLine() to read the lines and DataInputStream.read()
to read the bytes.
 
Reply With Quote
 
Tom Forsmo
Guest
Posts: n/a
 
      10-18-2006

EJP wrote:
> Tom Forsmo wrote:
>
>> 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

>
> Well you can't even do that for a start, you can't put an InputStream on
> top of a Reader.


No, but you can use the InputStream the Reader is based. Ok, its not
opening up a new InputStream, but you are still using the underlying
stream directly.

tom
 
Reply With Quote
 
EJP
Guest
Posts: n/a
 
      10-20-2006
Tom Forsmo wrote:
>>> 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

>>
>> Well you can't even do that for a start, you can't put an InputStream
>> on top of a Reader.

>
> No, but you can use the InputStream the Reader is based. Ok, its not
> opening up a new InputStream, but you are still using the underlying
> stream directly.


.... but you still won't get any of the data pushed back into the
PushbackInputStream!
 
Reply With Quote
 
EJP
Guest
Posts: n/a
 
      10-20-2006
Tom Forsmo wrote:
>>
>>> 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

>>
>> Well you can't even do that for a start, you can't put an InputStream
>> on top of a Reader.

>
> No, but you can use the InputStream the Reader is based. Ok, its not
> opening up a new InputStream, but you are still using the underlying
> stream directly.


.... but you still won't get any data pushed back into the PushbackReader!
 
Reply With Quote
 
Tom Forsmo
Guest
Posts: n/a
 
      10-21-2006

EJP wrote:
> .... but you still won't get any data pushed back into the PushbackReader!


I went back to the paragraph in the book I thought I read this, but I
must have misread it. I apologise for the confusion on that claim.

tom
 
Reply With Quote
 
Tom Forsmo
Guest
Posts: n/a
 
      10-21-2006

EJP wrote:
> Tom Forsmo wrote:
>>>
>>>> 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
>>>
>>> Well you can't even do that for a start, you can't put an InputStream
>>> on top of a Reader.

>>
>> No, but you can use the InputStream the Reader is based. Ok, its not
>> opening up a new InputStream, but you are still using the underlying
>> stream directly.

>
> .... but you still won't get any data pushed back into the PushbackReader!


I went back to the paragraph in the book I thought I read this, but I
must have misread it. I apologise for the confusion on that claim.

What you can do, though, is to use a PushbackInputStream. Your read some
bytes, give it to a reader which parses it, when the reader reaches the
binary data, it returns with a value stating how many bytes where
consumed by the reader. What was not consumed is pushed back into the
stream and you open up e.g. a DataInputStream to read the binary data.
When the DataInputStream is finished you could potentially return and
give control to the reader again, this way going back and forth between
text and binary. Its a bit complicated and not as clean. It would be
easier and cleaner to just use a complete binary or text based protocol
instead.

tom
 
Reply With Quote
 
 
 
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Ratio of Bytes Delayed to Bytes Sent netproj Cisco 0 12-21-2005 08:08 PM
4-bytes or 8-bytes alignment? mrby C Programming 8 11-02-2004 08:45 PM
Private Bytes vs. # Bytes in all Heaps in Perfmon Jason Collins ASP .Net 3 02-18-2004 03:59 PM
Re: receiving Bytes and sending Bytes Ieuan Adams Computer Support 0 07-24-2003 07:46 PM
Re: receiving Bytes and sending Bytes The Old Sourdough Computer Support 0 07-23-2003 01:23 PM



Advertisments