最近在看Netty框架，順便寫了一下NIO SocketChannel服務端和客戶端

Server.java

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

/**
 * Created by guanxianseng on 2017/8/18.
 */
public class Server {
    
 
private static void readMessage() throws IOException {
        ServerSocketChannel server = ServerSocketChannel.open();
        server.socket().bind(new InetSocketAddress(8888));
        while(true){
            SocketChannel client = server.accept();
            ByteBuffer buffer = ByteBuffer.allocate(1024);
            client.read(buffer);
            System.out.println(
 
"Server received msg = " + new String(buffer.array()));
            sendMessage(client);
        }
    }
    private static void sendMessage(SocketChannel client) throws IOException {
        ByteBuffer buffer = ByteBuffer.allocate(1024);
        String msg = "Server Time = " + System.currentTimeMillis();
        buffer.put(msg.getBytes());
        buffer.flip();
        client.write(buffer);
    }

    
 
public static void main(String[] args) throws IOException {
        readMessage();
    }
}

Client.java

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

/**
 * Created by guanxianseng on 2017/8/18.
 */
public class Client {
    private static SocketChannel client = null;

    static {
        try {
            init();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static void init() throws IOException {
        client  = SocketChannel.open();
        client.connect(new InetSocketAddress("127.0.0.1", 8888));
    }

    private static void sendMessage(String message) throws IOException {
        ByteBuffer buffer = ByteBuffer.allocate(1024);
        buffer.put(message.getBytes());
        buffer.flip();
        while(buffer.hasRemaining()){
            client.write(buffer);
        }
//        client.close();
    }

    private static void readMessage(){
        Thread reader = new Thread(new Runnable() {
            @Override
            public void run() {
                ByteBuffer buffer = ByteBuffer.allocate(1024);
                try {
                    client.read(buffer);
//                    buffer.flip();
                    System.out.println(new String(buffer.array()));
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        });
        reader.start();
    }

    public static void main(String[] args) throws IOException {
        sendMessage("hello nio");
        readMessage();
    }
}

整個套路和Socket、ServerSocket套路是一樣的，這是阻塞形式的。NIO可以設置為非阻塞，這需要配合使用Selector。這種就和Socket、ServerSocket就不一樣了

NIOSocket Server Client