带java选择器的无限循环

我是Java的新手，现在我对Java nio选择器感到困惑，下面是Java网络程序第三册中的代码

package org.eclipse.java.socket.samples;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
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 ChargenServer {
    public static int DEFAULT_PORT = 4321;
    public static void main(String[] args) {
        int port;
        try {
            port = Integer.parseInt(args[0]);
        }
        catch (Exception ex) {
            port = DEFAULT_PORT;
        }
        System.out.println("Listening for connections on port " + port);
        byte[] rotation = new byte[95 * 2];
        for (byte i = ' '; i <= '~'; i++) {
            rotation[i - ' '] = i;
            rotation[i + 95 - ' '] = i;
        }
        ServerSocketChannel serverChannel;
        Selector selector;
        try {
            serverChannel = ServerSocketChannel.open();
            ServerSocket ss = serverChannel.socket();
            InetSocketAddress address = new InetSocketAddress(port);
            ss.bind(address);
            serverChannel.configureBlocking(false);
            selector = Selector.open();
            serverChannel.register(selector, SelectionKey.OP_ACCEPT);
        }
        catch (IOException ex) {
            ex.printStackTrace();
            return;
        }
        while (true) {
            try {
                selector.select();
            }
            catch (IOException ex) {
                ex.printStackTrace();
                break;
            }            
            Set<SelectionKey> readyKeys = selector.selectedKeys();
            Iterator<SelectionKey> iterator = readyKeys.iterator();
            while (iterator.hasNext()) {
                SelectionKey key = (SelectionKey) iterator.next();
                iterator.remove();
                try {
                    if (key.isAcceptable()) {
                        ServerSocketChannel server = (ServerSocketChannel) key
                                .channel();
                        SocketChannel client = server.accept();
                        System.out
                                .println("Accepted connection from " + client);
                        client.configureBlocking(false);
                        SelectionKey key2 = client.register(selector,
                                SelectionKey.
                                OP_WRITE);
                        ByteBuffer buffer = ByteBuffer.allocate(74);
                        buffer.put(rotation, 0, 72);
                        buffer.put((byte) '\r');
                        buffer.put((byte) '\n');
                        buffer.flip();
                        key2.attach(buffer);
                    }
                    else if (key.isWritable()) {
                        SocketChannel client = (SocketChannel) key.channel();
                        ByteBuffer buffer = (ByteBuffer) key.attachment();
                        if (!buffer.hasRemaining()) {
                            // Refill the buffer with the next line
                            buffer.rewind();
                            // Get the old first character
                            int first = buffer.get();
                            // Get ready to change the data in the buffer
                            buffer.rewind();
                            // Find the new first characters position in
                            // rotation
                            int position = first - ' ' + 1;
                            // copy the data from rotation into the buffer
                            buffer.put(rotation, position, 72);
                            // Store a line break at the end of the buffer
                            buffer.put((byte) '\r');
                            buffer.put((byte) '\n');
                            // Prepare the buffer for writing
                            buffer.flip();
                            buffer.compact();
                        }
                        client.write(buffer);
                    }
                }
                catch (IOException ex) {
                    key.cancel();
                    try {
                        key.channel().close();
                    }
                    catch (IOException cex) {
                    }
                }
            }
        }
    }
}

在我的理解中，“selector.select（）”等待来自远程服务器的输入事件，然后它.remove（）删除此事件，因此选择器开始等待来自远程服务器的新事件，这样客户端就可以使用选择器连续地从服务器获取数据，但结果是一次又一次循环的，选择器对服务器的数据毫无意义， 为什么？

---

我的代码有问题吗

一旦您写入了所需的所有内容（即，当输出缓冲区为空时），您应该删除

OP\u WRITE

interest标志。

三个是与代码相关的多个问题，包括不关闭选择器

只有在写入操作无法写入整个缓冲区时，才需要注册

OP_WRITE

，否则需要取消注册。查看

interestedOps（）

通常，您需要OP_READ才能从该频道读取。 最后，总是在stackoverflow之前检查（这是我跟踪的bug之一）。建议：不要使用相同的选择器来接受/写入

---

干杯

我怀疑您的连接总是准备好写入，或者是时候让调试器出来看看发生了什么。就我个人而言，我在NIO中使用阻塞，而不是使用选择器，这使代码更加简单。（可以更快）阻塞非常简单，但当我需要管理多个连接时，选择器是一个完美的选择，而不是多个线程。您需要关闭与finally Blocks的连接，但我需要一个连续连接…您想通过套接字连接侦听particuler端口上的数据。。？

package org.eclipse.java.socket.selector;

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.SocketChannel;
import java.util.Iterator;
import java.util.Set;

public class SocketSelector {
    public static void main(String[] args) throws IOException {
        // Create selector
        Selector selector = null;
        selector = Selector.open();
        ////////////////////////////////////////////////////////////////////////
        SocketChannel socketChannel = SocketChannel.open(new InetSocketAddress(
                "localhost", 4321));
        socketChannel.configureBlocking(false);
        socketChannel.register(selector, SelectionKey.OP_CONNECT);
        /*
         * Let's begin select
         */
        while (true) {
            selector.select();
            System.out.println("Hello, selector!");
            Set readyKeys = selector.selectedKeys();
            Iterator it = readyKeys.iterator();  
            while (it.hasNext()) {
                SelectionKey key = (SelectionKey )it.next();
                if (key.isReadable()) {
                    System.out.println("It's readable!");
                }
                it.remove();
            }
        }
    }
}