【Java nio】 NonBlocking NIO

 package com.slp.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.Date;
 import java.util.Iterator;
 import java.util.Scanner;

 /**
  * Created by sanglp on 2017/3/2.
  * 一、使用NIO完成网络通信的三个核心
  * 1、通道：负责连接
  *     |--java.nio.channels.channel接口
  *        |--SelectableChannel
  *           |--SocketChannel
  *           |--ServerSocketChannel
  *           |--DatagramChannel
  *
  *           |--Pipe.SinkChannel
  *           |--Pipe.SourceChannel
  * 2、缓冲区：负责数据的存取
  * 3、选择器：是SelectableChannel的多路复用器，用于监控SelectableChannel的IO状况
  *
  */
 public class TestNonBlockingNIO {

     @Test
     public void client() throws IOException {
         //获取通道
         SocketChannel socketChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1",9898));
         //切换为非阻塞模式
       socketChannel.configureBlocking(false);
         //分配缓冲区
         ByteBuffer buf = ByteBuffer.allocate(1024);
         //发送数据给服务端

         Scanner scanner = new Scanner(System.in);
         while (scanner.hasNext()){
             String str = scanner.next();
             buf.put((new Date().toString()+"\n"+str).getBytes());
             buf.flip();
             socketChannel.write(buf);
             buf.clear();
         }

         //关闭通道
         socketChannel.close();

     }

     @Test
     public void server() throws IOException {
         //获取通道
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
         //切换非阻塞模式
         serverSocketChannel.configureBlocking(false);
         //绑定连接
         serverSocketChannel.bind(new InetSocketAddress(9898));
         //获取一个选择器
         Selector selector = Selector.open();
         //将通道注册到选择器上 并且指定监听接收事件
         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()){
                 //获取准备就绪的事件
                 SelectionKey sk = it.next();
                 //判断具体是什么事件准备就绪
                 if(sk.isAcceptable()){
                     //获取额护短连接
                     SocketChannel socketChannel = serverSocketChannel.accept();
                     //切换非阻塞模式
                     socketChannel.configureBlocking(false);
                     //将该通道注册到选择器上
                     socketChannel.register(selector,SelectionKey.OP_READ);
                 }else if(sk.isReadable()){
                     //获取当前选择器上读就绪状态的通道
                     SocketChannel socketChannel = (SocketChannel) sk.channel();
                     //读取数据
                     ByteBuffer buffer = ByteBuffer.allocate(1024);
                     int len =0;
                     while ((len=socketChannel.read(buffer))>0){
                         buffer.flip();
                         System.out.println(new String(buffer.array(),0,len));
                         buffer.clear();
                     }
                 }
                 //取消选择键
                 it.remove();
             }
         }
     }
 }