fork download
copy 
  1. import java.io.*;
  2. import java.net.*;
  3. import java.nio.*;
  4. import java.nio.channels.*;
  5. import java.util.*;
  6.  
  7. public class Server implements Runnable
  8. {
  9.   // The port we will listen on
  10.   private int port;
  11.  
  12.   // A pre-allocated buffer for encrypting data
  13.   private final ByteBuffer buffer = ByteBuffer.allocate( 16384 );
  14.  
  15.   public Server( int port ) {
  16.     this.port = port;
  17.     new Thread( this ).start();
  18.   }
  19.  
  20.   public void run() {
  21.     try {
  22.       // Instead of creating a ServerSocket,
  23.       // create a ServerSocketChannel
  24.       ServerSocketChannel ssc = ServerSocketChannel.open();
  25.  
  26.       // Set it to non-blocking, so we can use select
  27.       ssc.configureBlocking( false );
  28.  
  29.       // Get the Socket connected to this channel, and bind it
  30.       // to the listening port
  31.       ServerSocket ss = ssc.socket();
  32.       InetSocketAddress isa = new InetSocketAddress( port );
  33.       ss.bind( isa );
  34.  
  35.       // Create a new Selector for selecting
  36.       Selector selector = Selector.open();
  37.  
  38.       // Register the ServerSocketChannel, so we can
  39.       // listen for incoming connections
  40.       ssc.register( selector, SelectionKey.OP_ACCEPT );
  41.       System.out.println( "Listening on port "+port );
  42.  
  43.       while (true) {
  44.         // See if we've had any activity -- either
  45.         // an incoming connection, or incoming data on an
  46.         // existing connection
  47.         int num = selector.select();
  48.  
  49.         // If we don't have any activity, loop around and wait
  50.         // again
  51.         if (num == 0) {
  52.           continue;
  53.         }
  54.  
  55.         // Get the keys corresponding to the activity
  56.         // that has been detected, and process them
  57.         // one by one
  58.         Set keys = selector.selectedKeys();
  59.         Iterator it = keys.iterator();
  60.         while (it.hasNext()) {
  61.           // Get a key representing one of bits of I/O
  62.           // activity
  63.           SelectionKey key = (SelectionKey)it.next();
  64.  
  65.           // What kind of activity is it?
  66.           if ((key.readyOps() & SelectionKey.OP_ACCEPT) ==
  67.             SelectionKey.OP_ACCEPT) {
  68.  
  69. System.out.println( "acc" );
  70.             // It's an incoming connection.
  71.             // Register this socket with the Selector
  72.             // so we can listen for input on it
  73.  
  74.             Socket s = ss.accept();
  75.             System.out.println( "Got connection from "+s );
  76.  
  77.             // Make sure to make it non-blocking, so we can
  78.             // use a selector on it.
  79.             SocketChannel sc = s.getChannel();
  80.             sc.configureBlocking( false );
  81.  
  82.             // Register it with the selector, for reading
  83.             sc.register( selector, SelectionKey.OP_READ );
  84.           } else if ((key.readyOps() & SelectionKey.OP_READ) ==
  85.             SelectionKey.OP_READ) {
  86.  
  87.             SocketChannel sc = null;
  88.  
  89.             try {
  90.  
  91.               // It's incoming data on a connection, so
  92.               // process it
  93.               sc = (SocketChannel)key.channel();
  94.               boolean ok = processInput( sc );
  95.  
  96.               // If the connection is dead, then remove it
  97.               // from the selector and close it
  98.               if (!ok) {
  99.                 key.cancel();
  100.  
  101.                 Socket s = null;
  102.                 try {
  103.                   s = sc.socket();
  104.                   s.close();
  105.                 } catch( IOException ie ) {
  106.                   System.err.println( "Error closing socket "+s+": "+ie );
  107.                 }
  108.               }
  109.  
  110.             } catch( IOException ie ) {
  111.  
  112.               // On exception, remove this channel from the selector
  113.               key.cancel();
  114.  
  115.               try {
  116.                 sc.close();
  117.               } catch( IOException ie2 ) { System.out.println( ie2 ); }
  118.  
  119.               System.out.println( "Closed "+sc );
  120.             }
  121.           }
  122.         }
  123.  
  124.         // We remove the selected keys, because we've dealt
  125.         // with them.
  126.         keys.clear();
  127.       }
  128.     } catch( IOException ie ) {
  129.       System.err.println( ie );
  130.     }
  131.   }
  132.  
  133.   // Do some cheesy encryption on the incoming data,
  134.   // and send it back out
  135.   private boolean processInput( SocketChannel sc ) throws IOException {
  136.     buffer.clear();
  137.     sc.read( buffer );
  138.     buffer.flip();
  139.  
  140.     // If no data, close the connection
  141.     if (buffer.limit()==0) {
  142.       return false;
  143.     }
  144.  
  145.     // Simple rot-13 encryption
  146.     for (int i=0; i<buffer.limit(); ++i) {
  147.       byte b = buffer.get( i );
  148.  
  149.       if ((b>='a' && b<='m') || (b>='A' && b<='M')) {
  150.         b += 13;
  151.       } else if ((b>='n' && b<='z') || (b>='N' && b<='Z')) {
  152.         b -= 13;
  153.       }
  154.  
  155.       buffer.put( i, b );
  156.     }
  157.  
  158.     sc.write( buffer );
  159.  
  160.     System.out.println( "Processed "+buffer.limit()+" from "+sc );
  161.  
  162.     return true;
  163.   }
  164.  
  165.   static public void main( String args[] ) throws Exception {
  166.     int port = 7856;
  167.     new Server( port );
  168.   }
  169. }
Compilation error #stdin compilation error #stdout 0s 0KB
comments (?)
stdin
copy 
Standard input is empty
compilation info 
Main.java:7: error: class Server is public, should be declared in a file named Server.java
public class Server implements Runnable
       ^
1 error
stdout
copy 
Standard output is empty
https://ideone.com/mALCu5
language:
Java (HotSpot 12)
created:
7 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!