reading data from a java socket

English Programming/Scripting
1

Hello all,

I’m trying to write a serversocket that reads a postscript stream from a printer driver and writes that stream into a file.

I’m reading data in a while loop and trying to close the connection on input.readLine() = null but my problem is that if I use this statement I’ll lose some data.
Also I tried while(true) but my connection is not closing anymore(After all the stream is transmitted it keeps sending null to my file.)

How can I detect if socket activity is finished?

Thanks,
Ionut

2

Did you actually write input.readLine() = null in your program or is it correctly written as input.readLine() == null?

Also why are you using line oriented input? Postscript isn’t guaranteed to have line breaks regularly or even end with a line feed. Lots of PostScript files contain binary data. You should treat the data as a stream of bytes and not assume lines.

3

In my program I used while(input.readLine() != null){ read … data from socket};

And yes when I use input.readLine () seems that I loose some binary data.

So … what kind of methods I should use to read binary data and check if socket activity was finished?

4

Read data a block at a time. You should be able to find the javadoc for the class.

5

I’ll try that!

6

Thank you very much! I tried this way and it’s working.

7 
while(input.readLine() != null) {
    read data from the socket
}

Here, every alternate line is lost! You are reading a line to test if it is null or not. When you read again inside the loop, the line read in the conditional statement is already lost.

8

In the end I used something like:

byte] buf = new byte[4096];
for (int br = clientSocket.getInputStream().read(buf);
br > -1;
br = clientSocket.getInputStream().read(buf)) {

        outFile.write(buf, 0, br);

}

This way I was able to read all the data.

Thanks to all for the replies.

9

If you take advantage of testing the result of an assignment which IIRC works just as well in Java as in C, you can simplify that to:

int br = 0;
while ((br = clientSocket.getInputStream().read(buf)) > -1) {
   outFile.write(buf, 0, br);
}
10

[QUOTE=ken_yap;2104686]Did you actually write input.readLine() = null in your program or is it correctly written as input.readLine() == null?

Also why are you using line oriented input? Postscript isn’t guaranteed to have line breaks regularly or even end with a line feed. Lots of PostScript files contain binary data. You should treat the data as a stream of bytes and not assume lines.[/QUOTE]

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