java-nio实例代码

// $Id$ import java.io.*; import java.net.*; import java.nio.*; import java.nio.channels.*; import java.util.*; public class MultiPortEcho { private int ports[]; private ByteBuffer echoBuffer = ByteBuffer.allocate( 1024 ); public MultiPortEcho( int ports[] ) throws IOException { this.ports = ports; go(); } private void go() throws IOException { // Create a new selector Selector selector = Selector.open(); // Open a listener on each port, and register each one // with the selector for (int i=0; i<ports.length; ++i) { ServerSocketChannel ssc = ServerSocketChannel.open(); ssc.configureBlocking( false ); ServerSocket ss = ssc.socket(); InetSocketAddress address = new InetSocketAddress( ports[i] ); ss.bind( address ); SelectionKey key = ssc.register( selector, SelectionKey.OP_ACCEPT ); System.out.println( "Going to listen on "+ports[i] ); } while (true) { int num = selector.select(); Set selectedKeys = selector.selectedKeys(); Iterator it = selectedKeys.iterator(); while (it.hasNext()) { SelectionKey key = (SelectionKey)it.next(); if ((key.readyOps() & SelectionKey.OP_ACCEPT) == SelectionKey.OP_ACCEPT) { // Accept the new connection ServerSocketChannel ssc = (ServerSocketChannel)key.channel(); SocketChannel sc = ssc.accept(); sc.configureBlocking( false ); // Add the new connection to the selector SelectionKey newKey = sc.register( selector, SelectionKey.OP_READ ); it.remove(); System.out.println( "Got connection from "+sc ); } else if ((key.readyOps() & SelectionKey.OP_READ) == SelectionKey.OP_READ) { // Read the data SocketChannel sc = (SocketChannel)key.channel(); // Echo data int bytesEchoed = 0; while (true) { echoBuffer.clear(); int r = sc.read( echoBuffer ); if (r<=0) { break; } echoBuffer.flip(); sc.write( echoBuffer ); bytesEchoed += r; } System.out.println( "Echoed "+bytesEchoed+" from "+sc ); it.remove(); } } //System.out.println( "going to clear" ); // selectedKeys.clear(); //System.out.println( "cleared" ); } } static public void main( String args[] ) throws Exception { if (args.length<=0) { System.err.println( "Usage: java MultiPortEcho port [port port ...]" ); System.exit( 1 ); } int ports[] = new int[args.length]; for (int i=0; i<args.length; ++i) { ports[i] = Integer.parseInt( args[i] ); } new MultiPortEcho( ports ); } }