publicclassGroupChatServer {
//选择器privateSelectorselector ;
//服务端通道ServerSocketChannelserverSocketChannel ;
//初始化服务端publicGroupChatServer(){
try {
//创建选择器selector=Selector.open();
//创建通道serverSocketChannel=ServerSocketChannel.open();
//绑定监听端口serverSocketChannel.bind(newInetSocketAddress("127.0.0.1",5000));
//配置为异步serverSocketChannel.configureBlocking(false);
//注册通道到选择器serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
        } catch (Exceptione) {
e.printStackTrace();
        }
    }
//处理客户端监听publicvoidlisten(){
//轮询监听while(true){
//监听try {
if(selector.select() >0){
//监听到事件，获取到有事件的keySet<SelectionKey>selectionKeys=selector.selectedKeys();
Iterator<SelectionKey>iterator=selectionKeys.iterator();
while(iterator.hasNext()){
SelectionKeyselectionKey=iterator.next();
//如果是“接收就绪”if(selectionKey.isAcceptable()){
//注册通道SocketChannelchannel=serverSocketChannel.accept();
//设置为异步channel.configureBlocking(false);
//注册通道，监听类型设置为：“读” ，并指定装数据的Bufferchannel.register(selector,SelectionKey.OP_READ,ByteBuffer.allocate(1024));
System.out.println("客户端:"+channel.getRemoteAddress()+" 上线啦...");
                        }
//如果是“读就绪”if(selectionKey.isReadable()){
//读取数据 , 转发数据给其他客户readAndForwardMessage(selectionKey);
                        }
//删除Key防止重复处理iterator.remove();
                    }
                }else{
System.out.println("等待客户端加入...");
                }
            } catch (IOExceptione) {
e.printStackTrace();
            }
        }
    }
//读取数据publicvoidreadAndForwardMessage(SelectionKeyselectionKey){
SocketChannelchannel=null;
try {
//得到通道channel= (SocketChannel) selectionKey.channel();
//异步channel.configureBlocking(false);
//准备缓冲区ByteBufferbyteBuffer=ByteBuffer.allocate(1024);
//把数据读取到缓冲区channel.read(byteBuffer);
//打印结果Stringmessage=channel.getRemoteAddress()+" : "+newjava.lang.String(byteBuffer.array());
System.out.println(message);
//转发消息forwardToOthers(channel , message);
        } catch (IOExceptione) {
e.printStackTrace();
try {
//出现异常，关闭通道selectionKey.channel();
if(channel!=null){
channel.close();
                }
            } catch (IOExceptionex) {
ex.printStackTrace();
            }
        }
    }
//转发数据publicvoidforwardToOthers(SocketChannelself,Stringmessage){
//转发给所有通道Set<SelectionKey>keys=selector.keys();
Iterator<SelectionKey>iterator=keys.iterator();
while(iterator.hasNext()){
//拿到某一个客户端的keySelectionKeyselectionKey=iterator.next();
SelectableChannelselectableChannel=selectionKey.channel();
//排除当前发消息的客户端不用转发if(selectableChannelinstanceofSocketChannel&&selectableChannel!=self){
//转发SocketChannelchannel= (SocketChannel) selectableChannel;
try {
channel.write(ByteBuffer.wrap(message.getBytes()));
                } catch (IOExceptione) {
e.printStackTrace();
                }
            }
        }
    }
publicstaticvoidmain(String[] args) {
newGroupChatServer().listen();
    }
}

publicclassGroupChatClient {
//选择且privateSelectorselector ;
//服务端通道SocketChannelsocketChannel ;
//初始化服务端publicGroupChatClient(){
try {
//创建选择器selector=Selector.open();
//创建通道socketChannel=SocketChannel.open(newInetSocketAddress("127.0.0.1",5000));
//配置为异步socketChannel.configureBlocking(false);
//注册通道到选择器，客户端监听读事件socketChannel.register(selector, SelectionKey.OP_READ);
System.out.println(socketChannel.getLocalAddress()+"：准备完毕");
        } catch (Exceptione) {
e.printStackTrace();
        }
    }
//发送消息publicvoidsendMessage(Stringmessage){
try {
socketChannel.write(ByteBuffer.wrap(message.getBytes()));
        } catch (IOExceptione) {
e.printStackTrace();
        }
    }
//处理客户端监听publicvoidreadMessage(){
while (true){
try {
if(selector.select() >0){
//监听到有事件Iterator<SelectionKey>iterator=selector.selectedKeys().iterator();
while(iterator.hasNext()){
SelectionKeykey=iterator.next();
//如果是可读事件if(key.isReadable()){
//获取通道SocketChannelchannel= (SocketChannel) key.channel();
channel.configureBlocking(false);
//读取通道数据ByteBufferbyteBuffer=ByteBuffer.allocate(1024);
channel.read(byteBuffer);
//打印内容System.out.println(newString(byteBuffer.array()));
                        }
//防止重复操作iterator.remove();
                    }
                }else{
try {
Thread.sleep(3000);
                    } catch (InterruptedExceptione) {
e.printStackTrace();
                    }
                }
            } catch (IOExceptione) {
//e.printStackTrace();System.out.println("服务器关闭...");
            }
        }
    }
publicstaticvoidmain(String[] args) {
GroupChatClientgroupChatClient=newGroupChatClient();
//新开线程，专门处理服务端发送过来的消息，不然会阻塞主线程newThread(()->{
//读取消息groupChatClient.readMessage();
        }).start();
//写消息 , 键盘输入Scannerscanner=newScanner(System.in);
while(scanner.hasNextLine()){
Stringmessage=scanner.nextLine();
//发消息groupChatClient.sendMessage(message);
        }
    }
}