1.概要

1.1 说明

Netty NIO 非阻塞模式-CSDN博客

真对上面的问题，做些修正。主要解决如下问题。当客户端关闭或者强制关闭的时候，服务端关闭对应的SelectionKey。这样可以避免因异常退出，和不断的重复读取数据。

1.1.1客户端强制退出，下面的代码会包异常。所以需要要try catch捕获异常，以保证服务端正常运行。因为这时候这个“SelectionKey”已经没有用了，所以也需要取消。

SocketChannel socketChannel = (SocketChannel)selectionKey.channel();
ByteBuffer byteBuffer1 = ByteBuffer.allocate(16);
int len = socketChannel.read(byteBuffer1);

 1.1.2 客户端正常退出，会给服务端发送一次写的请求，但不写任何数据，这时候服务端可以判断客户端退出了，也删除SelectionKey”

                        if(len>0){。。。略}else {//如果没有都到数据，取消selectionKeyselectionKey.channel();}

2.代码

2.1 服务端

package com.xjc.springcloundtest;import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.SocketAddress;
import java.net.SocketOption;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Set;public class Main {public static void main(String[] args) throws IOException {ByteBuffer byteBuffer = ByteBuffer.allocate(16);Selector selector = Selector.open();ServerSocketChannel ssc = ServerSocketChannel.open();ssc.configureBlocking(false);SelectionKey sscKey = ssc.register(selector,0,null);sscKey.interestOps(SelectionKey.OP_ACCEPT);ssc.bind(new InetSocketAddress(8080));List<SocketChannel> channels = new ArrayList<>();while (true){//如果没有事件 就阻塞selector.select();Iterator<SelectionKey> iter = selector.selectedKeys().iterator();while (iter.hasNext()){SelectionKey selectionKey = iter.next();iter.remove();if(selectionKey.isAcceptable()){ServerSocketChannel ssc2 =  (ServerSocketChannel)selectionKey.channel();SocketChannel sc = ssc2.accept();sc.configureBlocking(false);SelectionKey sckey = sc.register(selector,0,null);sckey.interestOps(SelectionKey.OP_READ);}else if(selectionKey.isReadable()){try {SocketChannel socketChannel = (SocketChannel)selectionKey.channel();ByteBuffer byteBuffer1 = ByteBuffer.allocate(16);int len = socketChannel.read(byteBuffer1);if(len>0){byteBuffer.flip();while (byteBuffer.hasRemaining()){byte b = byteBuffer.get();System.out.println((char)b);}//这里也可以用下面的方式输出读到的内容//System.out.println(Charset.defaultCharset().decode(byteBuffer));byteBuffer.clear();System.out.println("read 后");}else {//如果没有都到数据，取消selectionKeyselectionKey.channel();}}catch (Exception e){e.printStackTrace();//如果发生异常取消selectionKeyselectionKey.channel();}}}/*System.out.println("accept 前");SocketChannel sc = ssc.accept();System.out.println("accept 后");if(sc!=null){sc.configureBlocking(false);channels.add(sc);}for (SocketChannel channel: channels){System.out.println("read 后");int len = channel.read(byteBuffer);if(len>0){byteBuffer.flip();while (byteBuffer.hasRemaining()){byte b = byteBuffer.get();System.out.println((char)b);}byteBuffer.clear();System.out.println("read 后");}}*/}//System.out.println("Hello world!");}
}

2.2 客户端

package com.xjc.springcloundtest;import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.channels.SocketChannel;
import java.nio.charset.Charset;public class Client {public static void main(String[] args) throws IOException {SocketChannel sc = SocketChannel.open();sc.connect(new InetSocketAddress("localhost", 8080));sc.write(Charset.defaultCharset().encode("helllo"));System.out.println("Hello world!");}
}