使用Netty做WebSocket服务端

　　使用Netty搭建WebSocket服务器

1.WebSocketServer.java

public class WebSocketServer {
    private final ChannelGroup group = new DefaultChannelGroup(ImmediateEventExecutor.INSTANCE);

    private final EventLoopGroup workerGroup = new NioEventLoopGroup();

    private Channel channel;

    public ChannelFuture start(InetSocketAddress address) {
        ServerBootstrap boot = new ServerBootstrap();
        boot.group(workerGroup).channel(NioServerSocketChannel.class).childHandler(createInitializer(group));

        ChannelFuture f = boot.bind(address).syncUninterruptibly();
        channel = f.channel();
        return f;
    }

    protected ChannelHandler createInitializer(ChannelGroup group2) {
        return new ChatServerInitializer(group2);
    }

    public void destroy() {
        if (channel != null)
            channel.close();
        group.close();
        workerGroup.shutdownGracefully();
    }

    public static void main(String[] args) {
        final WebSocketServer server = new WebSocketServer();
        ChannelFuture f = server.start(new InetSocketAddress(2048));
        System.out.println("server start................");
        Runtime.getRuntime().addShutdownHook(new Thread() {
            @Override
            public void run() {
                server.destroy();
            }
        });
        f.channel().closeFuture().syncUninterruptibly();
    }

    private static WebSocketServer instance;

    private WebSocketServer() {}

    public static synchronized WebSocketServer getInstance() {// 懒汉，线程安全
        if (instance == null) {
            instance = new WebSocketServer();
        }
        return instance;
    }

    public void running(){
        if(instance != null){
            
            String port=null;
            port=BusinessConfigUtils.findProperty("websocket_port");//获取端口号
            if(null==port||port.length()<0||!StringUtils.isNumeric(port)){
                port="18080";
            }
            instance.start(new InetSocketAddress(Integer.valueOf(port)));
            //ChannelFuture f = 
            System.out.println("----------------------------------------WEBSOCKET SERVER START----------------------------------------");
            /*Runtime.getRuntime().addShutdownHook(new Thread() {
                @Override
                public void run() {
                    instance.destroy();
                }
            });
            f.channel().closeFuture().syncUninterruptibly();*/
        }
    }
}

2.ChatServerInitializer.java

public class ChatServerInitializer extends ChannelInitializer<Channel> {

	private final ChannelGroup group;
	public ChatServerInitializer(ChannelGroup group) {
		super();
		this.group = group;
	}

	@Override
	protected void initChannel(Channel ch) throws Exception {
		ChannelPipeline pipeline = ch.pipeline();
		
		pipeline.addLast(new HttpServerCodec());
		
		pipeline.addLast(new ChunkedWriteHandler());
		
		pipeline.addLast(new HttpObjectAggregator(64*1024));
		
		pipeline.addLast(new HttpRequestHandler("/ws"));
		
		pipeline.addLast(new WebSocketServerProtocolHandler("/ws"));
		
		pipeline.addLast(new TextWebSocketFrameHandler(group));
		
	}

}

　3. HttpRequestHandler.java

public class HttpRequestHandler extends SimpleChannelInboundHandler<FullHttpRequest> {

	private LoginTimeService loginTimeService = SpringContextHolder.getBean("loginTimeServiceImpl");
	private final String wsUri;

	public HttpRequestHandler(String wsUri) {
		super();
		this.wsUri = wsUri;
	}

	@Override
	@SuppressWarnings("deprecation")
	protected void channelRead0(ChannelHandlerContext ctx, FullHttpRequest msg) throws Exception {
		if (wsUri.equalsIgnoreCase(msg.getUri().substring(0, 3))) {
			String userId = findUserIdByUri(msg.getUri());
			if (userId != null && userId.trim() != null && userId.trim().length() > 0) {
				ctx.channel().attr(AttributeKey.valueOf(ctx.channel().id().asShortText())).set(userId);// 写userid值
				UserIdToWebSocketChannelShare.userIdToWebSocketChannelMap.put(userId, ctx.channel()); // 用户Id与Channel绑定
				loginTimeService.onLine(userId, new Date());// 统计上线记录

			} else {
			}// 没有获取到用户Id
			ctx.fireChannelRead(msg.setUri(wsUri).retain());
		}
	}

	private String findUserIdByUri(String uri) {// 通过Uid获取用户Id--uri中包含userId
		String userId = "";
		try {
			userId = uri.substring(uri.indexOf("userId") + 7);
			if (userId != null && userId.trim() != null && userId.trim().length() > 0) {
				userId = userId.trim();
			}
		} catch (Exception e) {
		}
		return userId;
	}

	@Override
	public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
		ctx.close();
		cause.printStackTrace(System.err);
	}
}

　4. TextWebSocketFrameHandler.java

public class TextWebSocketFrameHandler extends SimpleChannelInboundHandler<TextWebSocketFrame> {

	private LoginTimeService loginTimeService = SpringContextHolder.getBean("loginTimeServiceImpl");
	private final ChannelGroup group;

	public TextWebSocketFrameHandler(ChannelGroup group) {
		super();
		this.group = group;
	}

	@Override
	public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
		if (evt == WebSocketServerProtocolHandler.ServerHandshakeStateEvent.HANDSHAKE_COMPLETE) {
			ctx.pipeline().remove(HttpRequestHandler.class);
			// group.writeAndFlush("");
			group.add(ctx.channel());
		} else {
			super.userEventTriggered(ctx, evt);
		}
	}

	@Override
	protected void channelRead0(ChannelHandlerContext ctx, TextWebSocketFrame msg) throws Exception {
		group.writeAndFlush(msg.retain());
	}

	@Override
	public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
		ctx.close();
		cause.printStackTrace();
	}

	@Override
	public void channelInactive(ChannelHandlerContext ctx) throws Exception { // (6)
		Channel incoming = ctx.channel();
		String userId = (String) incoming.attr(AttributeKey.valueOf(incoming.id().asShortText())).get();
		UserIdToWebSocketChannelShare.userIdToWebSocketChannelMap.remove(userId);// 删除缓存的通道
		loginTimeService.outLine(userId, new Date());// 下线通过
	}

}