Socket BIO & NIO

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.ServerSocket;
import java.net.Socket;

public class SocketBIO {
    public static void main(String[] args) throws IOException {
        ServerSocket serverSocket = new ServerSocket(9090, 20);
        System.out.println("step1: new ServerSocket(9090) ");
        while (true) {
            Socket client = serverSocket.accept();
            System.out.println("step2:client\t" + client.getPort());
            new Thread(()->{
                InputStream in = null;
                try {
                    in = client.getInputStream();
                    BufferedReader reader = new BufferedReader(new InputStreamReader(in));
                    while(true){
                        String dataline = reader.readLine(); //阻塞2
                        if(null != dataline){
                            System.out.println(dataline);
                        }else{
                            client.close();
                            break;
                        }
                    }
                    System.out.println("客户端断开");
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }).start();
        }
    }
}

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.LinkedList;

public class SocketNIO {
    public static void main(String[] args) throws IOException {
        LinkedList<SocketChannel> clients = new LinkedList<>();
        ServerSocketChannel ss = ServerSocketChannel.open();  //服务端开启监听：接受客户端
        ss.bind(new InetSocketAddress(9090));
        ss.configureBlocking(false);   //重点  OS  NONBLOCKING!!!  // 只让接受客户端  不阻塞
        while (true) {
            //接受客户端的连接
            SocketChannel client = ss.accept();//不会阻塞？  -1 NULL
            //accept  调用内核了：1，没有客户端连接进来，返回值？在BIO 的时候一直卡着，但是在NIO ，不卡着，返回-1，NULL
            //如果来客户端的连接，accept 返回的是这个客户端的fd  5，client  object
            //NONBLOCKING 就是代码能往下走了，只不过有不同的情况
            if (client == null) {
                //   System.out.println("null.....");
            } else {
                client.configureBlocking(false); //重点  socket（服务端的listen socket<连接请求三次握手后，往我这里扔，我去通过accept 得到  连接的socket>，连接socket<连接后的数据读写使用的> ）
                int port = client.socket().getPort();
                System.out.println("client..port: " + port);
                clients.add(client);
            }

            ByteBuffer buffer = ByteBuffer.allocateDirect(4096);  //可以在堆里   堆外

            //遍历已经链接进来的客户端能不能读写数据
            for (SocketChannel c : clients) {   //串行化！！！！  多线程！！
                int num = c.read(buffer);  // >0  -1  0   //不会阻塞
                if (num > 0) {
                    buffer.flip();
                    byte[] aaa = new byte[buffer.limit()];
                    buffer.get(aaa);
                    String b = new String(aaa);
                    System.out.println(c.socket().getPort() + " : " + b);
                    buffer.clear();
                }
            }
        }
    }
}