Transferring images through a socket

Question

Hi,
i'm writing a simplified webserver which gets a request from a client, gets the content from the origin server and returns it to the client as it is (currently..)
The problem is that the images i transfer are corrupted and i'm not sure why (i'm guessing something to do with asci/binary mode transfer) but i don't know what's the proper way to do this.
Right now i'm using InputStreamReader wrapped by BufferedReader to read the content.
Can someone please advice??
Thanks!!
Hesher.

Answer 1

I'm trying to transfer image / binary data through sockets for some time now and cannot manage to do so. I've read multiple threads where users describe similar problems, but I somehow can't get it to work and I don't know why. What I'm trying to do:
Server side:
1. Get length of file and send to client
2. Read image from file and send to client socket output stream
Client side:
1. Obtain length of file from server
2. Read image from server socket input stream and save to file
Step 1 works fine. The size of the file is transformed correctly. The next thing is that the server is transferring the byte data from the file to the outputstream and the client is transferring the byte data from the inputstream to another file. Here, I use a generic transfer method:
* This method transfers binary data.
* @param is The source of the data.
* @param os The destination of the data.
* @param len The length size/length of the data.
* @throws IOException
public static void transfer(InputStream is,
          OutputStream os,
          long len) throws IOException {
     // Initializing the buffer
     byte[] buf = new byte[1024];
     // Amount of bytes read in total
     long sent = 0;
     // Amount of bytes currently read
     int cur = 0;
     // Transfer data:
     while(                         // Stop when:
               (sent<len) &&          // enough data is sent OR
               ((cur=is.read(buf))!=-1)// end of stream is reached
          os.write(buf, 0, cur);          // send buffer to output stream
          os.flush();               // flush output stream
          sent += cur;               // increment count of bytes sent
}The success rate is about 50%, meaning about half the output images are corrupted, the other half is fine. If this helps at all to diagnose the problem: The failure images always have the same size.
Cheers and thanks in advance for any hints!