非阻塞式NIO 小案例（模拟聊天室）

package com.nio;
 
 
import org.junit.Test;
 
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.util.Date;
import java.util.Iterator;
import java.util.Scanner;
 
/**
 * 一、使用NIO完成网络通信的三个核心
 * 1.通道（Channel）:负责连接
 * java.nio.channels.Channel  接口
 * |--SelectableChannel
 * |--SocketChannel
 * |--ServerSocketChannel
 * |--DatagramChannel
 * <p>
 * |--Pipe.SinkChannel
 * |--Pipe.SourceChannel
 * <p>
 * 2.缓存区（Buffer）:负责数据的存取
 * 3.选择器（Selector）:是SelectableChannel 的多路复用器。用于监控SelectableChannel的IO状况
 * <p>
 * 注意：在启动的时候，先启动服务端，再启动客户端
 * <p>
 * 非阻塞式NIO  小案例
 */
public class TestNonBlockingNIO {
    @Test
    public void client() throws IOException {
        //1.获取通道
        SocketChannel sChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", 9898));
        //2.切换非阻塞模式
        sChannel.configureBlocking(false);
        //3.分配指定大小的缓存区
        ByteBuffer buf = ByteBuffer.allocate(1024);
        //4.发送数据给服务端
        Scanner scan = new Scanner(System.in);
        while (scan.hasNext()) {
            String str = scan.next();
            System.out.println("刚才输入的是：" + str);
            buf.put((new Date().toString() + "\n" + str).getBytes());
            buf.flip();
            sChannel.write(buf);
            buf.clear();
        }
        //5.关闭通道
        sChannel.close();
        System.out.println("客户端启动成功");
 
    }
 
    @Test
    public void server() throws IOException {
        //1.获取通道
        ServerSocketChannel ssChannel = ServerSocketChannel.open();
        //2.切换成非阻塞模式
        ssChannel.configureBlocking(false);
        //3.绑定连接
        ssChannel.bind(new InetSocketAddress(9898));
        //4.获取选择器
        Selector selector = Selector.open();
        //5.将通道注册到选择器上 ，并且指定监听接收事件
        ssChannel.register(selector, SelectionKey.OP_ACCEPT);
        //6.轮询式的获取选择器上已经准备就绪的事件
        while (selector.select() > 0) {
            //7.获取当前选择器中所有注册的  选择键（已就绪的监听事件）
            Iterator<SelectionKey> it = selector.selectedKeys().iterator();
            while (it.hasNext()) {
                //8.获取准备“就绪”的是事件
                SelectionKey sk = it.next();
                //9.判断具体是什么事件准备就绪
                if (sk.isAcceptable()) {
                    //10.若“接收就绪”，获取客户端连接
                    SocketChannel sChannel = ssChannel.accept();
                    //11.切换成非阻塞模式
                    sChannel.configureBlocking(false);
                    //12、将该通道注册到选择器上
                    sChannel.register(selector, SelectionKey.OP_READ);
 
 
                } else if (sk.isReadable()) {
                    //13.获取当前选择器上“读就绪”状态的通道
                    SocketChannel sChannel = (SocketChannel) sk.channel();
                    //14.读取数据
                    ByteBuffer buf = ByteBuffer.allocate(1024);
 
                    int len = 0;
                    while ((len = sChannel.read(buf)) > 0)
                        buf.flip();
                    System.out.println(new String(buf.array(), 0, buf.limit()));
                    buf.clear();
                }
            }
            //15.取消选择键 SelectionKey
            it.remove();
        }
        System.out.println("服务端启动成功");
    }
 
}