Java Tutorial/Network/ServerSocketChannel

Accepting a Connection on a ServerSocketChannel

   <source lang="java">

import java.net.InetSocketAddress; import java.nio.channels.ServerSocketChannel; import java.nio.channels.SocketChannel; public class Main {

 public static void main(String[] argv) throws Exception {
   ServerSocketChannel ssChannel = ServerSocketChannel.open();
   ssChannel.configureBlocking(false);
   int port = 80;
   ssChannel.socket().bind(new InetSocketAddress(port));
   int localPort = ssChannel.socket().getLocalPort();
   SocketChannel sChannel = ssChannel.accept();
   if (sChannel == null) {
   } else {
   }
 }

}</source>

Detecting When a Non-Blocking Socket Is Closed by the Remote Host

   <source lang="java">

import java.net.InetSocketAddress; import java.nio.ByteBuffer; import java.nio.channels.SelectionKey; import java.nio.channels.Selector; import java.nio.channels.ServerSocketChannel; import java.nio.channels.SocketChannel; import java.util.Iterator; public class Main {

 public static void main(String[] argv) throws Exception {
   Selector selector = Selector.open();
   ServerSocketChannel ssChannel1 = ServerSocketChannel.open();
   ssChannel1.configureBlocking(false);
   ssChannel1.socket().bind(new InetSocketAddress(80));
   ServerSocketChannel ssChannel2 = ServerSocketChannel.open();
   ssChannel2.configureBlocking(false);
   ssChannel2.socket().bind(new InetSocketAddress(81));
   ssChannel1.register(selector, SelectionKey.OP_ACCEPT);
   ssChannel2.register(selector, SelectionKey.OP_ACCEPT);
   while (true) {
     selector.select();
     Iterator it = selector.selectedKeys().iterator();
     while (it.hasNext()) {
       SelectionKey selKey = (SelectionKey) it.next();
       it.remove();
       if (selKey.isAcceptable()) {
         ServerSocketChannel ssChannel = (ServerSocketChannel) selKey.channel();
         SocketChannel sc = ssChannel.accept();
         ByteBuffer buf = ByteBuffer.allocate(100);
         int numBytesRead = sc.read(buf);
     
         if (numBytesRead == -1) {
             sc.close();
         } else {
             // Read the bytes from the buffer
         }
         int numBytesWritten = sc.write(buf);
       }
     }
   }
 }

}</source>

New IO Hello Server

   <source lang="java">

import java.net.InetSocketAddress; import java.net.SocketAddress; import java.nio.ByteBuffer; import java.nio.channels.ServerSocketChannel; import java.nio.channels.SocketChannel; public class MainClass {

 public final static int PORT = 2345;
 public static void main(String[] args) throws Exception {
   ServerSocketChannel serverChannel = ServerSocketChannel.open();
   SocketAddress port = new InetSocketAddress(PORT);
   serverChannel.socket().bind(port);
   while (true) {
     SocketChannel clientChannel = serverChannel.accept();
     String response = "Hello " + clientChannel.socket().getInetAddress() + " on port "
         + clientChannel.socket().getPort() + "\r\n";
     response += "This is " + serverChannel.socket() + " on port "
         + serverChannel.socket().getLocalPort() + "\r\n";
     byte[] data = response.getBytes("UTF-8");
     ByteBuffer buffer = ByteBuffer.wrap(data);
     while (buffer.hasRemaining())
       clientChannel.write(buffer);
     clientChannel.close();
   }
 }

}</source>

ServerSocketChannel

   <source lang="java">

import java.io.IOException; import java.net.InetSocketAddress; import java.nio.ByteBuffer; import java.nio.channels.SelectionKey; import java.nio.channels.Selector; import java.nio.channels.ServerSocketChannel; import java.nio.channels.SocketChannel; import java.util.Iterator; import java.util.Set; public class MainClass {

 private static byte[] data = new byte[255];
 public static void main(String[] args) throws IOException {
   for (int i = 0; i < data.length; i++)
     data[i] = (byte) i;
   ServerSocketChannel server = ServerSocketChannel.open();
   server.configureBlocking(false);
   server.socket().bind(new InetSocketAddress(9000));
   Selector selector = Selector.open();
   server.register(selector, SelectionKey.OP_ACCEPT);
   while (true) {
     selector.select();
     Set readyKeys = selector.selectedKeys();
     Iterator iterator = readyKeys.iterator();
     while (iterator.hasNext()) {
       SelectionKey key = (SelectionKey) iterator.next();
       iterator.remove();
       if (key.isAcceptable()) {
         SocketChannel client = server.accept();
         System.out.println("Accepted connection from " + client);
         client.configureBlocking(false);
         ByteBuffer source = ByteBuffer.wrap(data);
         SelectionKey key2 = client.register(selector, SelectionKey.OP_WRITE);
         key2.attach(source);
       } else if (key.isWritable()) {
         SocketChannel client = (SocketChannel) key.channel();
         ByteBuffer output = (ByteBuffer) key.attachment();
         if (!output.hasRemaining()) {
           output.rewind();
         }
         client.write(output);
       }
       key.channel().close();
     }
   }
 }

}</source>

Test non-blocking accept() using ServerSocketChannel

   <source lang="java">

import java.net.InetSocketAddress; import java.nio.ByteBuffer; import java.nio.channels.ServerSocketChannel; import java.nio.channels.SocketChannel; /**

* Test non-blocking accept() using ServerSocketChannel.
*/

public class MainClass {

 public static final String GREETING = "Hello I must be going.\r\n";
 public static void main(String[] argv) throws Exception {
   int port = 1234; // default
   ByteBuffer buffer = ByteBuffer.wrap(GREETING.getBytes());
   ServerSocketChannel ssc = ServerSocketChannel.open();
   ssc.socket().bind(new InetSocketAddress(port));
   ssc.configureBlocking(false);
   while (true) {
     System.out.println("Waiting for connections");
     SocketChannel sc = ssc.accept();
     if (sc == null) {
       Thread.sleep(2000);
     } else {
       System.out.println("Incoming connection from: " + sc.socket().getRemoteSocketAddress());
       buffer.rewind();
       sc.write(buffer);
       sc.close();
     }
   }
 }

}</source>

Using a Selector to Manage Non-Blocking Server Sockets

   <source lang="java">

import java.net.InetSocketAddress; import java.nio.ByteBuffer; import java.nio.channels.SelectionKey; import java.nio.channels.Selector; import java.nio.channels.ServerSocketChannel; import java.nio.channels.SocketChannel; import java.util.Iterator; public class Main {

 public static void main(String[] argv) throws Exception {
   Selector selector = Selector.open();
   ServerSocketChannel ssChannel1 = ServerSocketChannel.open();
   ssChannel1.configureBlocking(false);
   ssChannel1.socket().bind(new InetSocketAddress(80));
   ServerSocketChannel ssChannel2 = ServerSocketChannel.open();
   ssChannel2.configureBlocking(false);
   ssChannel2.socket().bind(new InetSocketAddress(81));
   ssChannel1.register(selector, SelectionKey.OP_ACCEPT);
   ssChannel2.register(selector, SelectionKey.OP_ACCEPT);
   while (true) {
     selector.select();
     Iterator it = selector.selectedKeys().iterator();
     while (it.hasNext()) {
       SelectionKey selKey = (SelectionKey) it.next();
       it.remove();
       if (selKey.isAcceptable()) {
         ServerSocketChannel ssChannel = (ServerSocketChannel) selKey.channel();
         SocketChannel sc = ssChannel.accept();
         ByteBuffer bb =ByteBuffer.allocate(100);
         sc.read(bb);
         
       }
     }
   }
 }

}</source>