How can i solve this problem. I got following error:
java.nio.channels.ClosedChannelException
This is coding:
public void run() { try { SocketChannel socketChannel = (SocketChannel) key.channel(); ByteBuffer buffer = ByteBuffer.allocate(512); int i1 = socketChannel.read(buffer); if (buffer.limit() == 0 || i1 == -1) { Socket s = null; try { s = socketChannel.socket(); s.close(); key.cancel(); } catch (IOException ie) { if (UnitDataServer.isLog) { log.error("Error closing socket " + s + ": " + ie); } } } else { buffer.flip(); if (UnitDataServer.isLog) { log.info(" Recvd Message from Unit : " + buffer.array()); } byte byteArray[] = buffer.array(); log.info("Byte Array length :" + byteArray.length); hexString = new StringBuffer(); for (int i = 0; i < i1 /* byteArray.length */; i++) { String hex = Integer.toHexString(0xFF & byteArray[i]); if (hex.length() == 1) { // could use a for loop, but we're only dealing with a // single byte hexString.append('0'); } hexString.append(hex); } hexString.trimToSize(); log.info("Hex String :" + hexString); Communicator.dataReceive(new DataReceive( socketChannel, hexString.toString(), dst)); } } catch (Exception e) { if (UnitDataServer.isLog) { // log.error(e); } try { socketChannel.socket().close(); key.cancel(); } catch (IOException ex) { if (UnitDataServer.isLog) { log.error(ex); } } }
}2 Answers
You have closed the channel and are still trying to use it.
There are several issues with your code.
First, your test for EOS is faulty. Remove the limit() == 0 test. That doesn't indicate EOS, it just indicates a zero length read, which can happen in non-blocking mode at any time. It doesn't mean the peer has closed his end of the connection, and it doesn't mean you should close your end.
Second, closing a channel closes the socket as well. You should close the channel only, not the socket.
Third, closing a channel cancels the key. You don't need to follow every close with a cancel.
You may also have failed to check whether a ready key is valid in the select loop before using it, e.g. for reading.
I continue to be amazed, and amused, and bemused, by the claim elsewhere in this thread that 'source code is untrue' under some circumstances.
0You need to fix/secure code that is throwing this exception. ClosedChannelException is ...
... thrown when an attempt is made to invoke or complete an I/O operation upon channel that is closed, or at least closed to that operation. That this exception is thrown does not necessarily imply that the channel is completely closed. A socket channel whose write half has been shut down, for example, may still be open for reading
(as described in Java 6 API)
But really, you would need to provide us code snipped and stack trace in order to get more detailed help.
