transfer binary files over network

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_kOws - 01 Sep 2007 15:12 GMT

Hi,
I'm writing a P2P java client/server program.
The clients connect to the server, send their file list, and the server
broadcast the "global" file list to all clients (the list
is an HashMap and I work with writeObj and readObj).
Once a client wants to download a file, it connects directly to the
client that holds the file:
I'm in troubles writing that last part... I'm quite confused about how
can I send a binary file over network. I'm trying to do it
this way:

[who sends after opening a socket to the remote peer]
.......
InputStream in = new BufferedInputStream(new FileInputStream(fileName));
OutputStream out = new BufferedOutputStream(socket.getOutputStream());
byte[] buffer = new byte[1000];

while(true){
int nBytes = in.read(buffer, 0 , 1000);
if (nBytes < 0)
break;
out.write(buffer, 0, nBytes);
}
out.flush();
out.close();
is.close();
.........

[who receive]
.........
Socket socket = new Socket(host, port);
BufferedReader is = new BufferedReader(new
InputStreamReader(socket.getInputStream());
byte[] buffer = new byte[1000];
while(true){
is.read(buffer);
//append the buffer to a new file
..............

This don't work, and I don't know if I'm doing in the right way.

Can someone, please, help me?

Thank you very much and sorry for the long post!
Regards,

G.

Reply to this Message

Roedy Green - 01 Sep 2007 15:29 GMT

>.........
>Socket socket = new Socket(host, port);
[quoted text clipped - 4 lines]
>is.read(buffer);
>//append the buffer to a new file

url = new URL( "snippets/ser/" + snippetName + ".ser" );
System.out.println( "fetching: " + url );
URLConnection urlc = url.openConnection();
if ( urlc == null )
{
throw new IOException(
"\007ailed to connect to document server." );
}
urlc.setAllowUserInteraction( false );
urlc.setDoInput( true );
urlc.setDoOutput( false );
urlc.setUseCaches( false );
urlc.connect();
InputStream is = urlc.getInputStream();
GZIPInputStream gzis =
new GZIPInputStream( is, 4096/* buffsize */ );
ois = new ObjectInputStream( gzis );

// R E A D, footprintversion, footprint, tokens
long expectedVersion = Footprint.serialVersionUID;
long fileVersion = (Long) ois.readObject();
if ( fileVersion != expectedVersion )
{
System.err
.println( "\007Stale "
+ snippetName
+ " Version "
+ fileVersion
+ " should be "
+ expectedVersion );
ois.close();
tokens = new Token[0];
return;
}

// we have to recompute it with our font metrics, but we
want the
// totalLines count.
footprint = (Footprint) ois.readObject();

tokens = (Token[]) ois.readObject();

// C L O S E
ois.close();
}
catch ( InvalidClassException e )
{
System.err.println( "\007Stale " + snippetName );
}
catch ( ClassNotFoundException e )
{
System.err
.println( "\007Bug: Token class files missing from
jar " + e
.getMessage() );
}
catch ( IOException e )
{
e.printStackTrace();
System.err
.println( "\007Problem getting compacted source
document "

+ snippetName + " : " + e.getMessage()
);
}

Signature

Roedy Green Canadian Mind Products
The Java Glossary
http://mindprod.com

Reply to this Message

Esmond Pitt - 02 Sep 2007 11:17 GMT

> GZIPInputStream gzis =
> new GZIPInputStream( is, 4096/* buffsize */ );

How can that possibly work when the sending code doesn't use
GZIPOutputStream?

Reply to this Message

Roedy Green - 03 Sep 2007 03:17 GMT

On Sun, 02 Sep 2007 10:17:01 GMT, Esmond Pitt
<esmond.pitt@nospam.bigpond.com> wrote, quoted or indirectly quoted
someone who said :

>How can that possibly work when the sending code doesn't use
>GZIPOutputStream?

I am simply giving him some quoted sample code, not handing him the
solution on a plate. I trust he is smart enough to either GZip the
other end or remove the GZip.

Signature

Roedy Green Canadian Mind Products
The Java Glossary
http://mindprod.com

Reply to this Message

Luke Yan - 01 Sep 2007 16:15 GMT

hi, _kOws
it seems you code is right, so can you give some detail about "This don't
work"

Luke

ÔÚ Sat, 01 Sep 2007 16:12:31 +0200 Ê±, _kOws <kows@wanadoo.fr> Ð´ÁË:
--

>Hi,
>I'm writing a P2P java client/server program.
[quoted text clipped - 43 lines]
>
>G.

gumpagain@163.com
/**
/* Java Is Not Platform-independent.It Is The Platform!
*/

Reply to this Message

Real Gagnon - 01 Sep 2007 17:25 GMT

_kOws <kows@wanadoo.fr> wrote in news:qreCi.1200$Th1.442
@tornado.fastwebnet.it:

> [who receive]
> .........
> Socket socket = new Socket(host, port);
> BufferedReader is = new BufferedReader(new
> InputStreamReader(socket.getInputStream());

BufferedReader is more appropriate for text than binary.

For a very simple example about file transfer, take a look at
http://www.rgagnon.com/javadetails/java-0542.html

Bye.

Signature

Real Gagnon from Quebec, Canada
* Java, Javascript, VBScript and PowerBuilder code snippets
* http://www.rgagnon.com/howto.html
* http://www.rgagnon.com/bigindex.html

Reply to this Message

_kOws - 01 Sep 2007 22:07 GMT

Thank you, you all for the answers!

Real Gagnon ha scritto:

> _kOws <kows@wanadoo.fr> wrote in news:qreCi.1200$Th1.442
> @tornado.fastwebnet.it:
[quoted text clipped - 9 lines]
> For a very simple example about file transfer, take a look at
> http://www.rgagnon.com/javadetails/java-0542.html

oh thank you!
I knew I were doing wrong, and you put me on the right way!

I ask here avoiding to open another thread...sorry for this!

I want to "draw" a bar that indicates the progress of the download.
In my GUI I'm using only swing components.
Has anyone something to suggest for this?

> Bye.

Thank you again!

Regards.

Gabriele

Reply to this Message

Christian - 01 Sep 2007 22:38 GMT

_kOws schrieb:

> I want to "draw" a bar that indicates the progress of the download.
> In my GUI I'm using only swing components.
> Has anyone something to suggest for this?

this may be what you are looking for:
http://java.sun.com/docs/books/tutorial/uiswing/components/progress.html

> Regards.
>
> Gabriele

Reply to this Message

Roedy Green - 03 Sep 2007 03:18 GMT

>I want to "draw" a bar that indicates the progress of the download.
>In my GUI I'm using only swing components.
>Has anyone something to suggest for this?

see http://mindprod.com/jgloss/progress.html

Signature

Roedy Green Canadian Mind Products
The Java Glossary
http://mindprod.com

Reply to this Message

Christian - 01 Sep 2007 19:46 GMT

_kOws schrieb:

> Hi,
> I'm writing a P2P java client/server program.

Client-Server and P2P seems to be a contradiction in itself.

> The clients connect to the server, send their file list, and the server
> broadcast the "global" file list to all clients (the list
> is an HashMap and I work with writeObj and readObj).

this is again not peer-to-peer but client server structure..

> Once a client wants to download a file, it connects directly to the
> client that holds the file:

I am curious.. why do you implement such a concept? I mean peer-to-peer
systems have moved on .. what you described is basically the protocol
Napster used.. the oldest "peer-to-peer"-network that exists (or no
longer exists because of this protocol)..

Christian

Reply to this Message

_kOws - 01 Sep 2007 21:56 GMT

Christian ha scritto:

> _kOws schrieb:
>> Hi,
>> I'm writing a P2P java client/server program.
>
> Client-Server and P2P seems to be a contradiction in itself.

Yes you are right, but in this case the server is the program that
broadcasts
the list of files, that every client sends when get connected.

>> The clients connect to the server, send their file list, and the server
>> broadcast the "global" file list to all clients (the list
[quoted text clipped - 8 lines]
> Napster used.. the oldest "peer-to-peer"-network that exists (or no
> longer exists because of this protocol)..

you are right again... I'm writing it for an exam about networking and java,
and is the first time I use java!

I used to program in C or C++, and writing a program with a GUI in java
with Eclipse
was just amazing! :)

> Christian

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transfer binary files over network

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