NIO的简单Demo

package jesse.test1;

import java.io.IOException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.nio.charset.Charset;
import java.util.Iterator;
import java.util.Set;

public class NIOServer extends Thread{

    @Override
    public void run(){
        try {
            // 1，创建Selector 和 Channel
            Selector selector = Selector.open();
            ServerSocketChannel serverSocket = ServerSocketChannel.open();
            //
            serverSocket.bind(new InetSocketAddress(InetAddress.getLocalHost(), 8888));
            serverSocket.configureBlocking(false);
            // 注册到Selector，并说明关注点
            serverSocket.register(selector, SelectionKey.OP_ACCEPT);
            while(true){
                //阻塞等待就绪的Channel
                selector.select();
                Set<SelectionKey> selectedKeys = selector.selectedKeys();
                Iterator<SelectionKey> iter = selectedKeys.iterator();
                while(iter.hasNext()){
                    SelectionKey key = iter.next();
                    // 生产中一般会额外进行就绪状态检查
                    sayHelloWorld((ServerSocketChannel) key.channel());
                    iter.remove();
                }
            }

        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private void sayHelloWorld(ServerSocketChannel server){
        try {
            SocketChannel client = server.accept();
            client.write(Charset.defaultCharset().encode("hello World."));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        /*NIOServer server = new NIOServer();
        server.start();
        try {
            Socket client = new Socket(InetAddress.getLocalHost(), 8888);
            BufferedReader bufferReader = new BufferedReader(new InputStreamReader(client.getInputStream()));
            System.out.println(bufferReader.readLine());

        } catch (IOException e) {
            e.printStackTrace();
        }*/
        System.out.println("hello world");
        ThreadGroup group = Thread.currentThread().getThreadGroup();
        ThreadGroup topGroup = group;
        while (group != null) {
        topGroup = group;
        group = group.getParent();
        }
        int nowThreads = topGroup.activeCount();
        Thread[] lstThreads = new Thread[nowThreads];
        topGroup.enumerate(lstThreads);
        for (int i = 0; i < nowThreads; i++) {
        System.out.println("线程number：" + i + " = " + lstThreads[i].getName());
        }

    }
}
/**
 * 1、通过Selector.open 创建Selector，类似调度员
 * 2、创建一个ServerSocketChannel，并且注册到Selector上，指定SelectionKey.OP_ACCEPT,接收新的连接请求
 * 3、Selector阻塞在select请求，当有Channel发生接入请求，会被唤醒
 * 4、通过SocketChannel和Buffer进行数据操作，
 */