reading bytes with BufferedReader?

Discussion in 'Java' started by R, Oct 17, 2006.

  1. R

    R Guest

    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?
    R, Oct 17, 2006
    #1
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  2. R

    Guest

    On Oct 17, 3:24 am, "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).
    >
    > 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?
    , Oct 17, 2006
    #2
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  3. R

    Tom Forsmo Guest

    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
    Tom Forsmo, Oct 17, 2006
    #3
  4. R

    EJP Guest

    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.
    EJP, Oct 18, 2006
    #4
  5. R

    Tom Forsmo Guest

    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
    Tom Forsmo, Oct 18, 2006
    #5
  6. R

    EJP Guest

    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!
    EJP, Oct 20, 2006
    #6
  7. R

    EJP Guest

    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!
    EJP, Oct 20, 2006
    #7
  8. R

    Tom Forsmo Guest

    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
    Tom Forsmo, Oct 21, 2006
    #8
  9. R

    Tom Forsmo Guest

    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
    Tom Forsmo, Oct 21, 2006
    #9
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