<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <optional>true</optional>
</dependency>
<dependency>
    <groupId>io.netty</groupId>
    <artifactId>netty-all</artifactId>
    <version>4.1.28.Final</version>
</dependency>

/**
 * 服務端基本配置，通過一個靜態(tài)單例類，保證啟動時候只被加載一次
 */
@Component
public class WsServer {
	/**
	 * 單例靜態(tài)內部類
	 */
	public static class SingletionWServer{
		static final WsServer instance = new WsServer(); 
	}
	public static WsServer getInstance(){
		return SingletionWServer.instance;
	}
	private EventLoopGroup mainGroup ;
	private EventLoopGroup subGroup;
	private ServerBootstrap server;
	private ChannelFuture future;
	public WsServer(){
		mainGroup = new NioEventLoopGroup();
		subGroup = new NioEventLoopGroup();
		server = new ServerBootstrap();
		server.group(mainGroup, subGroup)
				.channel(NioServerSocketChannel.class)
				.childHandler(new WsServerInitialzer());//添加自定義初始化處理器
	}
	public void start(){
		future = this.server.bind(8081);
		System.err.println("netty 服務端啟動完畢 .....");
	}
}

public class WsServerInitialzer extends ChannelInitializer<SocketChannel>{
	@Override
	protected void initChannel(SocketChannel ch) throws Exception {
		ChannelPipeline pipeline = ch.pipeline();
		//websocket基于http協(xié)議，所以需要http編解碼器
		pipeline.addLast(new HttpServerCodec());
		//添加對于讀寫大數(shù)據(jù)流的支持
		pipeline.addLast(new ChunkedWriteHandler());
		//對httpMessage進行聚合
		pipeline.addLast(new HttpObjectAggregator(1024*64));
		// ================= 上述是用于支持http協(xié)議的 ==============
		//websocket 服務器處理的協(xié)議，用于給指定的客戶端進行連接訪問的路由地址
		//比如處理一些握手動作(ping,pong)
		pipeline.addLast(new WebSocketServerProtocolHandler("/ws"));
		//自定義handler
		pipeline.addLast(new ChatHandler());
	}
}

/**
 * 上文中需要自定義處理的handler
 * TextWebSocketFrame  用于為websockt處理文本的對象
 */
public class ChatHandler extends SimpleChannelInboundHandler<TextWebSocketFrame>{
	//用于記錄和管理所有客戶端的channel
	private static ChannelGroup clients = 
			new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
	@Override
	protected void messageReceived(ChannelHandlerContext ctx, TextWebSocketFrame msg) 
			throws Exception {
		//客戶端傳遞過來的消息
		String content = msg.text();
		System.out.println("接收到了客戶端的消息是:" + content);
		//將客戶端發(fā)送過來的消息刷到所有的channel中
		for(Channel channel : clients){
			channel.writeAndFlush(
					new TextWebSocketFrame("[服務器接收到了客戶端的消息:]" + LocalDateTime.now()+",消息為:" + content));
		}	
	}
	//客戶端創(chuàng)建的時候觸發(fā)，當客戶端連接上服務端之后，就可以獲取該channel，然后放到channelGroup中進行統(tǒng)一管理	
	@Override
	public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
		clients.add(ctx.channel());
	}
	//客戶端銷毀的時候觸發(fā)，
	@Override
	public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
		//當handlerRemoved 被觸發(fā)時候，channelGroup會自動移除對應的channel
		//clients.remove(ctx.channel());
		System.out.println("客戶端斷開，當前被移除的channel的短ID是：" +ctx.channel().id().asShortText());
	}
}

/**
 * netty服務端啟動加載配置
 */
@Component
public class NettybootServerInitConfig implements ApplicationListener<ContextRefreshedEvent>{
	@Override
	public void onApplicationEvent(ContextRefreshedEvent event) {
		if(event.getApplicationContext().getParent() == null){
			WsServer.getInstance().start();
		}
	}
}