由于功能太过简单，就不过多阐述了，直接上阻塞式代码：

package com.lql.nio;

import org.junit.Test;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;

/**
 * @author: lql
 * @date: 2019.11.01
 * Description: 客户端发送一条数据给服务端，服务端接收后反馈一条信息
 */
public class TestBlockingNIO2 {

    @Test
    public void client() {
        SocketChannel socketChannel = null;
        FileChannel inChannel = null;
        try {
            //获取通道
            socketChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", 8002));
            inChannel = FileChannel.open(Paths.get("2.png"), StandardOpenOption.READ);

            //获取缓冲区
            ByteBuffer byteBuffer = ByteBuffer.allocate(1024);

            while (inChannel.read(byteBuffer) != -1) {
                byteBuffer.flip();
                socketChannel.write(byteBuffer);
                byteBuffer.clear();
            }

            //切断
            socketChannel.shutdownOutput();

            //接收服务器端的反馈
            int len = 0;
            while ((len = socketChannel.read(byteBuffer)) != -1) {
                byteBuffer.flip();
                System.out.println(new String(byteBuffer.array(), 0, len));
                byteBuffer.clear();
            }


        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (inChannel != null) {
                try {
                    inChannel.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (socketChannel != null) {
                try {
                    socketChannel.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }


    @Test
    public void server() {
        ServerSocketChannel serverSocketChannel = null;
        FileChannel outChannel = null;
        try {
            serverSocketChannel = ServerSocketChannel.open();
            outChannel = FileChannel.open(Paths.get("wy.png"), StandardOpenOption.WRITE, StandardOpenOption.CREATE);

            SocketChannel socketChannel = serverSocketChannel.bind(new InetSocketAddress("127.0.0.1", 8002)).accept();
            ByteBuffer buffer = ByteBuffer.allocate(1024);
            while (socketChannel.read(buffer) != -1) {
                buffer.flip();
                outChannel.write(buffer);
                buffer.clear();
            }

            //接收完发送反馈给客户端
            buffer.put("服务器端接收客户端数据成功！！！".getBytes());
            buffer.flip();
            socketChannel.write(buffer);

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (outChannel != null) {
                try {
                    outChannel.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (serverSocketChannel != null) {
                try {
                    serverSocketChannel.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

    }
}

 

 接来下是非阻塞式的代码：

package com.lql.nio;

import org.junit.Test;

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.time.LocalDateTime;
import java.util.Iterator;

/**
 * @author: lql
 * @date: 2019.11.01
 * Description: 非阻塞式(得有Channel,Buffer,Selector)
 */
public class TestNonBlockingNIO {

    //客户端
    @Test
    public void client() {
        SocketChannel socketChannel = null;
        try {
            //获取通道
            socketChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", 8006));
            //切换成非阻塞模式
            socketChannel.configureBlocking(false);
            //获取缓冲区
            ByteBuffer buf = ByteBuffer.allocate(1024);
            //发送数据给服务端
            buf.put(LocalDateTime.now().toString().getBytes());
            buf.flip();
            socketChannel.write(buf);
            buf.clear();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (socketChannel != null) {
                try {
                    socketChannel.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }


    }


    @Test
    public void Server() {

        ServerSocketChannel serverSocketChannel = null;
        try {
            serverSocketChannel = ServerSocketChannel.open();
            //切换非阻塞模式
            serverSocketChannel.configureBlocking(false);
            //绑定并接收
            serverSocketChannel.bind(new InetSocketAddress("127.0.0.1", 8006));
            //获取选择器
            Selector selector = Selector.open();
            //将通道注册到选择器上,指定监听“接收”事件
            serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);

            //轮询式的获取选择器上已经“准备就绪”的事件
            while (selector.select() > 0) {
                //获取所有监听的事件
                Iterator<SelectionKey> it = selector.selectedKeys().iterator();

                while (it.hasNext()) {
                    //获取准备就绪的事件
                    SelectionKey key = it.next();

                    //判断具体是什么事件准备就绪
                    if (key.isAcceptable()) {
                        //获取客户端链接
                        SocketChannel socketChannel = serverSocketChannel.accept();

                        //客户端通道切换成非阻塞
                        socketChannel.configureBlocking(false);

                        //将该通道注册要选择器上
                        socketChannel.register(selector, SelectionKey.OP_READ);
                    } else if (key.isReadable()) {
                        //获取读就绪状态的通道
                        SocketChannel socketChannel = (SocketChannel) key.channel();

                        //读取数据
                        ByteBuffer buffer = ByteBuffer.allocate(1024);
                        int len = 0;
                        while ((len = socketChannel.read(buffer)) != -1) {
                            buffer.flip();

                            System.out.println(new String(buffer.array(), 0, len));
                            buffer.clear();
                        }

                    }
                    //取消选择键
                    it.remove();
                }

            }


        } catch (IOException e) {
            e.printStackTrace();
        } finally {

        }


    }

}