通过Java中的套接字传输文件

Question

i am trying to transfer file through socket in java..actually i have been able to transfer..but there is one problem occured..the problem is the file sent is shrink in size..for example i transfer 300mb file, the client will receive only 299mb....i was wondering what might be the problem..

Server Side

File myFile = new File (basePath+"\\"+input.readUTF());
byte [] mybytearray  = new byte [1024];
FileInputStream fis = new FileInputStream(myFile);
BufferedInputStream bis = new BufferedInputStream(fis);
txtArea.append("Sending... \n");
while (true)
{
    int i = bis.read(mybytearray, 0, mybytearray.length);
            if (i == -1) {
        break;
    }
    output.write(mybytearray, 0, i);
    txtArea.append("Sending chunk " + i + "\n");

}
output.flush();

Client Side

output.writeUTF("get");
txtArea.append("Starting to recive file... \n");
                long start = System.currentTimeMillis();
                byte [] mybytearray  = new byte [1024];
                txtArea.append("Connecting... \n");
                output.writeUTF(remoteSelection);
                FileOutputStream fos = new FileOutputStream(basePath+"\\"+remoteSelection);
                BufferedOutputStream bos = new BufferedOutputStream(fos);
                int bytesRead = input.read(mybytearray, 0, mybytearray.length);
                while(bytesRead != -1) 
                {
                    bos.write(mybytearray, 0, bytesRead);
                    txtArea.append("got chunk" + bytesRead +"\n");
                    bytesRead = input.read(mybytearray, 0, mybytearray.length);
                }
bos.flush();

Answer 1

The canonical way to copy a stream in Java is as follows:

int count;
byte[] buffer = new byte[8192]; // or whatever you like really, not too small
while ((count = in.read(buffer)) > 0)
{
   out.write(buffer, 0, count);
}

Works for any length input; does not load the entire input into memory; does not add latency by so doing.

If you are sending more than one file you need to send the length first, via DataOutputStream.writeLong(); read it at the other end via the inverse function; and adjust the loop condition at the reading end to terminate after reading exactly that many bytes. Not quite as simple as it may appear; left as an exercise for the reader.