之前實作的聊天室由於使用了阻塞式的 IO 在等待使用者輸入指令時整個執行緒都必須暫停 所以說線上有幾個使用者就等於我們要同時開啟幾條執行緒 這是非常浪費資源的 在後來的 java 版本有提供了非阻塞式的 IO 讓我們可以只用一條執行緒就可以應付許多連線 這次就使用 AsynchronousServerSocketChannel 來實作聊天室 (簡稱 AIO) 以下就是聊天室的程式碼 由於 AIO 有非常多的細節, 但是我們的目的是要開發 MUD 因此這邊我不打算解釋的太詳細 // GeneralAioEchoServer.java // ✂--------------請沿虛線剪下-------------- package test; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.net.InetSocketAddress; import java.nio.ByteBuffer; import java.nio.channels.AsynchronousChannelGroup; import java.nio.channels.AsynchronousServerSocketChannel; import java.nio.channels.AsynchronousSocketChannel; import java.nio.channels.CompletionHandler; import java.nio.charset.StandardCharsets; import java.util.HashSet; import java.util.LinkedList; import java.util.Queue; import java.util.Set; import java.util.concurrent.*; public class GeneralAioEchoServer { private AsynchronousServerSocketChannel assc; private Set<AsynchronousSocketChannel> users = new HashSet<>(); public static void main(String[] args) throws Exception { GeneralAioEchoServer server = new GeneralAioEchoServer(); server.start(); // AIO 因為不會阻塞, 所以必須要有無限迴圈來維持 main thread while (true) { Thread.sleep(5000L); } } // 建立連線池, 設定 server port, 啟動 private void start() throws IOException { ExecutorService pool = Executors.newSingleThreadExecutor(); AsynchronousChannelGroup channelGroup = AsynchronousChannelGroup.withThreadPool(pool); assc = AsynchronousServerSocketChannel.open(channelGroup); assc.bind(new InetSocketAddress(4000)); // 設定 callback method assc.accept(null, new AcceptHandler()); } private class AcceptHandler implements CompletionHandler<AsynchronousSocketChannel, Object> { @Override public void completed(AsynchronousSocketChannel asc, Object o) { assc.accept(null, this); try { asc.write(StandardCharsets.UTF_8.encode( "歡迎來到 aio telnet chat server\r\n")).get(); } catch (InterruptedException | ExecutionException e) { e.printStackTrace(); } ByteBuffer bb = ByteBuffer.allocate(1024); asc.read(bb, null, new ReadHandler(asc, bb)); users.add(asc); } @Override public void failed(Throwable throwable, Object o) { } } private class ReadHandler implements CompletionHandler<Integer, Object> { private AsynchronousSocketChannel asc; private ByteBuffer bb; private MyByteArrayOutputStream byteArrayOutputStream = new MyByteArrayOutputStream(); private boolean firstChar = true; private Queue<String> inputs = new LinkedList<>(); public ReadHandler(AsynchronousSocketChannel asc, ByteBuffer bb) { this.asc = asc; this.bb = bb; } @Override public void completed(Integer result, Object o) { if (result == -1) return; // 逐 byte 讀取玩家輸入的字元 byte[] bytes = new byte[result]; bb.flip().get(bytes).clear(); for (byte b : bytes) { switch (b) { case '\n': if (firstChar) { firstChar = false; continue; } case '\r': inputs.offer( new String(byteArrayOutputStream.toByteArray(), StandardCharsets.UTF_8)); byteArrayOutputStream.reset(); firstChar = true; continue; case 127: byteArrayOutputStream.backspace(); continue; default: byteArrayOutputStream.write(b); firstChar = false; } } try { while (!inputs.isEmpty()) { String message = inputs.poll() + "\r\n"; for (AsynchronousSocketChannel user : users) { user.write(StandardCharsets.UTF_8.encode(message)).get(); } } } catch (InterruptedException | ExecutionException e) { e.printStackTrace(); } asc.read(bb, null, this); } @Override public void failed(Throwable throwable, Object o) { } } // 繼承ByteArrayOutputStream 實作 backspace 的功能 private static class MyByteArrayOutputStream extends ByteArrayOutputStream { public void backspace() { if (count > 0) count--; } } } // ✂--------------請沿虛線剪下-------------- 如此一來, 更輕量化的聊天室就完成了 下一次我們會開始實作登入系統 -- ╔═◢ ◣═╦╦═════╦═════╗ ║ ◤◤◤ ◥ ╠╣飛鳥ももこ╠═╗ ║ ║ ▇ ▇ ║╚═════╝ ╚═╦═╣ ║ ▌ ● ● ▌ ║╔══════╗╔═╩═╣ ║◤ ◥ ︺█◤ ◥╠╣Momoko Asuka╠╝ ║ ╚◣◢ ▄▂▄ ◣◢╩╩══════╩════╝ --

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