1、nio实现socket

服务段

package socketnio;

import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.util.Iterator;
import java.util.Set;

public class NioSocketServer {

    static Selector selector = null;
    static ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
    public static void main(String[] args) throws Exception{
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();

        //必须设置成非阻塞的
        serverSocketChannel.configureBlocking(false);

        serverSocketChannel.bind(new InetSocketAddress("127.0.0.1",9999));


        selector = Selector.open();

        serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);

        while (true){
            if(selector.select(3000) == 0){
                System.out.println("未获取到客户端链接当前线程非阻塞运行");
                continue;
            }


            Set<SelectionKey> selectionKeys = selector.selectedKeys();

            Iterator<SelectionKey> iterator = selectionKeys.iterator();

            while (iterator.hasNext()){

                SelectionKey next = iterator.next();

                //客户端发起连接
                if(next.isAcceptable()){
                    acceptAdapter(next);
                }else if (next.isReadable()){
                    readAdapter(next);
                }else if (next.isWritable()){
                    witerAdapter(next);
                }
                iterator.remove();
            }
        }
    }

    public static void acceptAdapter(SelectionKey selectionKey) throws Exception{

        ServerSocketChannel channel = (ServerSocketChannel)selectionKey.channel();

        SocketChannel accept = channel.accept();

        accept.configureBlocking(false);


        accept.register(selector,SelectionKey.OP_READ);
        System.out.println("当前客户端已经绑定到选择器READ事件中" + accept.getRemoteAddress().toString());

    }

    public static void readAdapter(SelectionKey selectionKey) throws Exception{
        SocketChannel channel = (SocketChannel)selectionKey.channel();

        byteBuffer.clear();
        int a;

        int read = channel.read(byteBuffer);
        byteBuffer.flip();
        System.out.println("客户端传递的内容为:" + new String(byteBuffer.array(),0,read));
        channel.register(selector,SelectionKey.OP_WRITE);

    }

    public static void witerAdapter(SelectionKey selectionKey) throws Exception{
        SocketChannel channel = (SocketChannel)selectionKey.channel();

        byteBuffer.clear();
        byteBuffer.put("收到消息了".getBytes());
        byteBuffer.flip();

        channel.write(byteBuffer);

        channel.register(selector,SelectionKey.OP_READ);

    }
}

客户端

package socketnio;

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.Scanner;
import java.util.Set;

public class NioSocketClient {
    static Selector selector = null;

    public static void main(String[] args)throws Exception {

        Scanner scanner = new Scanner(System.in);
        SocketChannel socketChannel = SocketChannel.open();
        socketChannel.configureBlocking(false);

        selector = Selector.open();

        socketChannel.register(selector, SelectionKey.OP_CONNECT);


        socketChannel.connect(new InetSocketAddress("127.0.0.1",9999));



        while (true){
            selector.select();
            Set<SelectionKey> selectionKeys = selector.selectedKeys();

            Iterator<SelectionKey> iterator = selectionKeys.iterator();
            while (iterator.hasNext()){
                SelectionKey next = iterator.next();

                if (next.isConnectable()){
                    System.out.println("开始客户端链接");
                    socketChannel.finishConnect();
                    socketChannel.register(selector,SelectionKey.OP_WRITE);
                }else if (next.isWritable()){
                    System.out.println("请输入要发送的信息:");
                    String result = scanner.next();

                    ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
                    byteBuffer.put(result.getBytes());
                    byteBuffer.flip();
                    socketChannel.write(byteBuffer);

                    socketChannel.register(selector,SelectionKey.OP_READ);
                    System.out.println("结束~！！！~~~~");
                }else if (next.isReadable()){
                    System.out.print("服务端返回的消息:");
                    int c = 0;
                    ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
                    StringBuffer stringBuffer = new StringBuffer();
                    int read = socketChannel.read(byteBuffer);
                    System.out.println(new String(byteBuffer.array(),0,read));
                    socketChannel.register(selector,SelectionKey.OP_WRITE);
                }
            }
        }
    }
}