java nio demo

最新推荐文章于 2024-01-29 11:36:10 发布

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本文介绍了一个简单的NIO服务端和客户端实现案例，通过Java NIO中的ServerSocketChannel和SocketChannel进行非阻塞通信。服务端监听8989端口接收客户端连接，并向客户端发送欢迎消息；客户端连接到服务端后读取并打印服务端发来的消息。

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Server

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;

public class Server {
    private Selector selector;

    public void initServer() throws IOException {
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
        serverSocketChannel.configureBlocking(false);
        serverSocketChannel.socket().bind(new InetSocketAddress(8989));

        selector = Selector.open();
        serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);

    }

    public void listen() throws IOException {
        System.out.println("server started");
        while (true) {
            selector.select();
            Iterator iterator = selector.selectedKeys().iterator();
            while (iterator.hasNext()) {
                SelectionKey selectionKey = (SelectionKey) iterator.next();
                iterator.remove();
                if (selectionKey.isAcceptable()) {
                    ServerSocketChannel serverSocketChannel = (ServerSocketChannel) selectionKey.channel();
                    SocketChannel socketChannel = serverSocketChannel.accept();
                    socketChannel.configureBlocking(false);
                    socketChannel.write(ByteBuffer.wrap("hello client, from server".getBytes()));
                    socketChannel.register(selector, SelectionKey.OP_READ);
                } else if (selectionKey.isReadable()) {
                    read(selectionKey);
                }
            }
        }
    }

    public void read(SelectionKey key) throws IOException {
        SocketChannel socketChannel = (SocketChannel) key.channel();
        ByteBuffer byteBuffer = ByteBuffer.allocate(100);
        socketChannel.read(byteBuffer);
        byteBuffer.flip();
        System.out.println("get client message:" + new String(byteBuffer.array()));
        socketChannel.write(ByteBuffer.wrap("i got your msg client, from server".getBytes()));
    }

    public static void main(String[] args) throws IOException {
        Server server = new Server();
        server.initServer();
        server.listen();
    }
}

Client

import java.io.IOException;
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;

public class Client {

    private Selector selector;

    public void initClient() throws IOException {
        SocketChannel socketChannel = SocketChannel.open();
        socketChannel.configureBlocking(false);
        socketChannel.connect(new InetSocketAddress("localhost", 8989));

        selector = Selector.open();
        socketChannel.register(selector, SelectionKey.OP_CONNECT);
    }

    public void listen() throws IOException {
        while (true) {
            selector.select();
            Iterator iterator = selector.selectedKeys().iterator();
            while (iterator.hasNext()) {
                SelectionKey selectionKey = (SelectionKey) iterator.next();
                iterator.remove();
                if (selectionKey.isConnectable()) {
                    SocketChannel socketChannel = (SocketChannel) selectionKey.channel();
                    if (socketChannel.isConnectionPending()) {
                        socketChannel.finishConnect();
                    }

                    socketChannel.configureBlocking(false);
                    socketChannel.write(ByteBuffer.wrap("hello server, i want to connect".getBytes()));
                    socketChannel.register(selector, SelectionKey.OP_READ);

                } else if (selectionKey.isReadable()) {
                    read(selectionKey);
                }
            }

        }
    }

    public void read(SelectionKey selectionKey) throws IOException {
        SocketChannel socketChannel = (SocketChannel) selectionKey.channel();
        ByteBuffer byteBuffer = ByteBuffer.allocate(100);
        socketChannel.read(byteBuffer);
        byteBuffer.flip();
        System.out.println("get msg from server:" + new String(byteBuffer.array()));
    }

    public static void main(String[] args) throws IOException {
        Client client = new Client();
        client.initClient();
        client.listen();
    }
}