socket通道类ServerSocketChannel和DatagramChannel

ServerSocketChannel

ServerSocketChannel是一个基于通道的socket监听器。它同我们所熟悉的 java.net.ServerSocket 执行相同的任务，不过它增加了通道语义，因此能够在非阻塞 模式下运行。

由于 ServerSocketChannel 没有 bind()方法，因此有必要取出对等的 socket 并使用 它来绑定到一个端口以开始监听连接。我们也是使用对等 ServerSocket 的 API 来根 据需要设置其他的 socket

package NIOTest.channel.socket;

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

public class serverSocketChannelDemo {
    public static void main(String[] args) throws IOException, InterruptedException {
        //端口号
        int port=4444;
        //buffer缓冲区
        ByteBuffer byteBuffer = ByteBuffer.wrap("啊啊".getBytes());

        //ServerSocketChannel是一个基于socket监听器
        ServerSocketChannel ssc = ServerSocketChannel.open();

        //绑定通道对象，首先通过ServerSocketChannel.socket获取一个socket对象，然后绑定一个端口
        // 开始监听连接.
        ssc.socket().bind(new InetSocketAddress(port));

        //设置非阻塞模式
        ssc.configureBlocking(false);

        while (true){
            System.out.println("Waiting for connections");
            //一直监听有没有新的连接传入
            SocketChannel sc = ssc.accept();
            if (sc==null){//没有连接的传入
                Thread.sleep(1000);
                System.out.println("没有连接传入 null");
            }else {
                Thread.sleep(1000);
                System.out.println("connections:"+sc.socket().getRemoteSocketAddress());
                byteBuffer.rewind();
                sc.write(byteBuffer);
                sc.close();
            }
        }
    }
}

DatagramChannel 则模拟包 导向的无连接协议（如 UDP/IP)

package NIOTest.channel.socket;

import org.junit.jupiter.api.Test;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.DatagramChannel;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;

public class DatagramChannelDemo {

    //发送的实现
    @Test
    public void sendDatagram() throws Exception {
        //打开DatagramChannel
        DatagramChannel datagramChannel = DatagramChannel.open();
        InetSocketAddress senAddress = new InetSocketAddress("127.0.0.1",9999);
        //发送
        while (true){
            ByteBuffer byteBuffer = ByteBuffer.wrap("张凯".getBytes(StandardCharsets.UTF_8));
            datagramChannel.send(byteBuffer,senAddress);
            System.out.println("发送");
            Thread.sleep(1000);
        }
    }

    //接受的实现
    @Test
    public void receiveDatagram() throws IOException {
        //打开DatagramChannel
        DatagramChannel receiveChannel = DatagramChannel.open();
        InetSocketAddress receiveSocketAddress = new InetSocketAddress(9999);
        //绑定
        receiveChannel.bind(receiveSocketAddress);

        //buffer
        ByteBuffer byteBuffer = ByteBuffer.allocate(512);
        //接受
        while (true){
            byteBuffer.clear();
            SocketAddress socket = receiveChannel.receive(byteBuffer);
            byteBuffer.flip();
            System.out.println(socket.toString());
            System.out.println(StandardCharsets.UTF_8.decode(byteBuffer));

        }
    }
}

DatagramSocket实现假连接 

  UDP 不存在真正意义上的连接，这里的连接是向特定服务地址用 read 和 write 接收 发送数据包

package NIOTest.channel.socket;

import org.junit.jupiter.api.Test;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.DatagramChannel;
import java.nio.charset.StandardCharsets;

public class DatagramChannelReadWriter {
    public static void main(String[] args) {

    }

    @Test
    public void buildConnect() throws Exception {
        DatagramChannel datagramChannel  = DatagramChannel.open();
        InetSocketAddress inetSocketAddress = new InetSocketAddress("127.0.0.1", 9999);
        datagramChannel.bind(new InetSocketAddress(9999));

        ByteBuffer sendBuffer = ByteBuffer.wrap("欧文啊啊啊aaaa".getBytes(StandardCharsets.UTF_8));
        ByteBuffer receive = ByteBuffer.allocate(1024);
        datagramChannel.send(sendBuffer,inetSocketAddress);

            receive.clear();
            SocketAddress receive1 = datagramChannel.receive(receive);
            receive.flip();
            System.out.println(receive1.toString());
            System.out.println(StandardCharsets.UTF_8.decode(receive));
            datagramChannel.close();


    }
}