【从BIO到Netty】2.NIO线程模型

package org.scaventz.nio.mine;


import io.netty.util.CharsetUtil;

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 NioEchoServer {
    public static void main(String[] args) throws IOException {
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
        serverSocketChannel.socket().bind(new InetSocketAddress(8080));
        // 设置为非阻塞
        serverSocketChannel.configureBlocking(false);

        // 获得一个 Selector 对象
        Selector selector = Selector.open();
        // 将我们的 serverSocketChannel 注册到 selector上，注册的事件为 ACCEPT事件
        serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);

        while (true) {
            // 阻塞等待，也可以选择不阻塞 比如select(1000)，等待1ms
            selector.select();
            Set keys = selector.selectedKeys();
            Iterator keysIterator = keys.iterator();
            while (keysIterator.hasNext()) {
                SelectionKey key = keysIterator.next();
                if (key.isAcceptable()) {
                    System.out.println("连接事件到来");
                    SocketChannel socketChannel = serverSocketChannel.accept();
                    socketChannel.configureBlocking(false);
                    socketChannel.register(selector, SelectionKey.OP_READ, ByteBuffer.allocate(4096));
                    keysIterator.remove();
                    continue;
                }
                if (key.isReadable()) {
                    SocketChannel channel = (SocketChannel) key.channel();
                    ByteBuffer buffer = (ByteBuffer) key.attachment();
                    channel.read(buffer);
                    System.out.print("收到客户端信息: " + new String(buffer.array(), CharsetUtil.UTF_8));
                    // 回复客户端
                    channel.write(buffer);
                    keysIterator.remove();
                }
            }
        }
    }
}