java.nio.channels.IllegalBlockingModeException while reading content from client through a channel
Am very new to NIO am building a chat application i got connection in all the client but while reading content from client i got java.nio.channels.IllegalBlockingModeException. please help me here is the code where the exception occures. while reaching while (rbc.read(b) != -1) of PrintRequest class Exception occures
public class PrintRequest extends Thread
{
public PrintRequest(SocketChannel sc,int i)throws Exception
{
System.out.println("going to enter the try block of PrintRequest");
try
{
System.out.println("Am in the try block of PrintRequest");
ReadableByteChannel rbc = Channels.newChannel(sc.socket().getInputStream());
System.out.println("checking in PrintRequest 0001");
WritableByteChannel wbc = Channels.newChannel(System.out);
System.out.println("checking in PrintRequest 0010");
ByteBuffer b = ByteBuffer.allocateDirect(1024); // read 1024 bytes
// int numBytesRead = sc.read(b);
System.out.println("checking in PrintRequest 0011");
while (rbc.read(b) != -1)
{
System.out.println("Am in while loop of PrintRequest ");
b.flip();
while (b.hasRemaining())
{
wbc.write(b);
System.out.println();
}
b.clear();
}
}
catch(Exception E)
{
System.out.println("Exception in printlnRequest "+E);
}
} }
my server code:
public class Server
{
private Selector selector;
private ServerSocketChannel channel;
public void listner()
{
try
{
this.selector = Selector.open();
this.channel = ServerSocketChannel.open();
this.channel.configureBlocking(false);
this.channel.socket().bind(new InetSocketAddress(8888));
this.channel.register(this.selector, 16);
}
catch (IOException e)
{
throw new RuntimeException("Could not register listener", e);
}}
public void non_Socket()throws Exception
{
try
{
int i=0;
this.channel = ServerSocketChannel.open();
this.channel.configureBlocking(false);
this.channel.socket().bind(new InetSocketAddress(80));
while(true)
{
this.selector = Selector.open();
this.channel.register(this.selector, 16);
Set<SelectionKey> keys = this.selector.selectedKeys();
Iterator<SelectionKey> iterator = keys.iterator();
int readyChannels = selector.select();
if(readyChannels == 0) continue;
Set<SelectionKey> selectedKeys = selector.selectedKeys();
Iterator<SelectionKey> keyIterator = selectedKeys.iterator();
while(keyIterator.hasNext())
{
SelectionKey key = keyIterator.next();
if(key.isAcceptable())
{
// a connection was accepted by a ServerSocketChannel.
System.out.println("a connection was accepted by a ServerSocketChannel");
SocketChannel sc = this.channel.accept();
sc.configureBlocking(false);
System.out.println("Received an incoming connection from " + sc.socket().getRemoteSocketAddress());
System.out.println("checking 0101");
// new PrintRequest(sc,i).start();
System.out.println("checking 0110");
if(sc == null )
{
System.out.println("Please login");
Thread.sleep(6000);
}
else
{
System.out.println("Last Login was successful");
// new PrintRequest(sc,i).start();
PrintRequest pr=new PrintRequest(sc,i);
new Thread(pr).start();
}
}
else if (key.isConnectable())
{
// a connection was established with a remote server.
System.out.println("a connection was established with a remote server");
}
else if (key.isWritable())
{
// a channel is ready for writing
System.out.println(" a channel is ready for writing");
}
else if (key.isReadable())
{
// a channel is ready for reading
System.out.println(" a channel is ready for Reading");
}
System.out.println(" a channel is prepare for Reading");
keyIterator.remove();
Thread.sleep(5000);
}
}
}
catch(Exception E)
{
System.out.println(" Here : "+E);
}
finally
{
if (channel != null)
{
try
{
channel.close();
}
catch (Exception e)
{
e.printStackTrace();
}
}
}
}
public static void main(String [] abc) throws Exception
{
new Server().non_Socket();
}}
Client side:
public class Client
{
public void non_Client_Socket()
{
SocketChannel sChannel=null;
try
{
sChannel = SocketChannel.open();
sChannel.connect(new InetSocketAddress("localhost", 80));
while (!sChannel.finishConnect())
{
System.out.println("Channel is not connected yet");
Thread.sleep(5000);
}
System.out.println("Channel is ready to use");
/* ---------- going to send data to server ------------*/
System.out.println("please enter the text");
BufferedReader stdin=new BufferedReader(new InputStreamReader(System.in));
while(true)
{
System.out.println("Enter the text");
String HELLO_REQUEST =stdin.readLine().toString();
if(HELLO_REQUEST.equalsIgnoreCase("end"))
{
break;
}
System.out.println("Sending a request to HelloServer");
ByteBuffer buffer = ByteBuffer.wrap(HELLO_REQUEST.getBytes());
sChannel.write(buffer);
}
}
catch(Exception E)
{
}
finally
{
if (sChannel != null)
{
try
{
sChannel.close();
}
catch (Exception e)
{
e.printStackTrace();
}
}
} }
/* ---------- the data is written in sChannel server will read from this channel ------------ */
public static void main(String [] args)throws Exception
{
new Client().non_Client_Socket();
}}
Answer
ReadableByteChannel rbc = Channels.newChannel(sc.socket().getInputStream());
Your problem is here. You can't use a stream from a channel that's in non-blocking mode. The code is pointless anyway, as sc already is a ReadableByteChannel. Just delete this line and do the following I/O with sc instead of rbc. But see below.
You still haven't fixed any of the issues I mentioned in your previous post. Your connect technique is still wrong, and you are calling PrintRequest() which loops reading in non-blocking mode instead of registering the accepted channel for OP_READ. The code continues to make no sense.