前言:
如今大家对“nettysocketio和websocket”都比较看重,我们都想要剖析一些“nettysocketio和websocket”的相关知识。那么小编在网摘上网罗了一些关于“nettysocketio和websocket””的相关内容,希望同学们能喜欢,同学们一起来学习一下吧!1. 核心依赖
<dependencies> <!--netty的依赖集合,都整合在一个依赖里面了--> <dependency> <groupId>io.netty</groupId> <artifactId>netty-all</artifactId> <version>4.1.6.Final</version> </dependency></dependencies>2. 代码2.1 启动项
public class NioWebSocketServer { private final Logger logger=Logger.getLogger(this.getClass()); private void init(){ logger.info("正在启动websocket服务器"); NioEventLoopGroup boss=new NioEventLoopGroup(); NioEventLoopGroup work=new NioEventLoopGroup(); try { ServerBootstrap bootstrap=new ServerBootstrap(); bootstrap.group(boss,work); bootstrap.channel(NioServerSocketChannel.class); bootstrap.childHandler(new NioWebSocketChannelInitializer()); Channel channel = bootstrap.bind(8081).sync().channel(); logger.info("webSocket服务器启动成功:"+channel); channel.closeFuture().sync(); } catch (InterruptedException e) { e.printStackTrace(); logger.info("运行出错:"+e); }finally { boss.shutdownGracefully(); work.shutdownGracefully(); logger.info("websocket服务器已关闭"); } } public static void main(String[] args) { new NioWebSocketServer().init(); }}
netty搭建的服务器基本上都是差不多的写法:
绑定主线程组和工作线程组,这部分对应架构图中的事件循环组只有服务器才需要绑定端口,客户端是绑定一个地址配置channel(数据通道)参数,重点就是ChannelInitializer的配置以异步的方式启动,最后是结束关闭两个线程组2.2 ChannelInitializer写法
public class NioWebSocketChannelInitializer extends ChannelInitializer<SocketChannel> { @Override protected void initChannel(SocketChannel ch) { ch.pipeline().addLast("logging",new LoggingHandler("DEBUG"));//设置log监听器,并且日志级别为debug,方便观察运行流程 ch.pipeline().addLast("http-codec",new HttpServerCodec());//设置解码器 ch.pipeline().addLast("aggregator",new HttpObjectAggregator(65536));//聚合器,使用websocket会用到 ch.pipeline().addLast("http-chunked",new ChunkedWriteHandler());//用于大数据的分区传输 ch.pipeline().addLast("handler",new NioWebSocketHandler());//自定义的业务handler }}2.3 自定义的处理器NioWebSocketHandler
public class NioWebSocketHandler extends SimpleChannelInboundHandler<Object> { private final Logger logger=Logger.getLogger(this.getClass()); private WebSocketServerHandshaker handshaker; @Override protected void channelRead0(ChannelHandlerContext ctx, Object msg) throws Exception { logger.debug("收到消息:"+msg); if (msg instanceof FullHttpRequest){ //以http请求形式接入,但是走的是websocket handleHttpRequest(ctx, (FullHttpRequest) msg); }else if (msg instanceof WebSocketFrame){ //处理websocket客户端的消息 handlerWebSocketFrame(ctx, (WebSocketFrame) msg); } } @Override public void channelActive(ChannelHandlerContext ctx) throws Exception { //添加连接 logger.debug("客户端加入连接:"+ctx.channel()); ChannelSupervise.addChannel(ctx.channel()); } @Override public void channelInactive(ChannelHandlerContext ctx) throws Exception { //断开连接 logger.debug("客户端断开连接:"+ctx.channel()); ChannelSupervise.removeChannel(ctx.channel()); } @Override public void channelReadComplete(ChannelHandlerContext ctx) throws Exception { ctx.flush(); } private void handlerWebSocketFrame(ChannelHandlerContext ctx, WebSocketFrame frame){ // 判断是否关闭链路的指令 if (frame instanceof CloseWebSocketFrame) { handshaker.close(ctx.channel(), (CloseWebSocketFrame) frame.retain()); return; } // 判断是否ping消息 if (frame instanceof PingWebSocketFrame) { ctx.channel().write( new PongWebSocketFrame(frame.content().retain())); return; } // 本例程仅支持文本消息,不支持二进制消息 if (!(frame instanceof TextWebSocketFrame)) { logger.debug("本例程仅支持文本消息,不支持二进制消息"); throw new UnsupportedOperationException(String.format( "%s frame types not supported", frame.getClass().getName())); } // 返回应答消息 String request = ((TextWebSocketFrame) frame).text(); logger.debug("服务端收到:" + request); TextWebSocketFrame tws = new TextWebSocketFrame(new Date().toString() + ctx.channel().id() + ":" + request); // 群发 ChannelSupervise.send2All(tws); // 返回【谁发的发给谁】 // ctx.channel().writeAndFlush(tws); } /** * 唯一的一次http请求,用于创建websocket * */ private void handleHttpRequest(ChannelHandlerContext ctx, FullHttpRequest req) { //要求Upgrade为websocket,过滤掉get/Post if (!req.decoderResult().isSuccess() || (!"websocket".equals(req.headers().get("Upgrade")))) { //若不是websocket方式,则创建BAD_REQUEST的req,返回给客户端 sendHttpResponse(ctx, req, new DefaultFullHttpResponse( HttpVersion.HTTP_1_1, HttpResponseStatus.BAD_REQUEST)); return; } WebSocketServerHandshakerFactory wsFactory = new WebSocketServerHandshakerFactory( "ws://localhost:8081/websocket", null, false); handshaker = wsFactory.newHandshaker(req); if (handshaker == null) { WebSocketServerHandshakerFactory .sendUnsupportedVersionResponse(ctx.channel()); } else { handshaker.handshake(ctx.channel(), req); } } /** * 拒绝不合法的请求,并返回错误信息 * */ private static void sendHttpResponse(ChannelHandlerContext ctx, FullHttpRequest req, DefaultFullHttpResponse res) { // 返回应答给客户端 if (res.status().code() != 200) { ByteBuf buf = Unpooled.copiedBuffer(res.status().toString(), CharsetUtil.UTF_8); res.content().writeBytes(buf); buf.release(); } ChannelFuture f = ctx.channel().writeAndFlush(res); // 如果是非Keep-Alive,关闭连接 if (!isKeepAlive(req) || res.status().code() != 200) { f.addListener(ChannelFutureListener.CLOSE); } }}
执行流程是:
web发起一次类似是http的请求,并在channelRead0方法中进行处理,并通过instanceof去判断帧对象是FullHttpRequest还是WebSocketFrame,建立连接是时候会是FullHttpRequest在handleHttpRequest方法中去创建websocket,首先是判断Upgrade是不是websocket协议,若不是则通过sendHttpResponse将错误信息返回给客户端,紧接着通过WebSocketServerHandshakerFactory创建socket对象并通过handshaker握手创建连接在连接创建好后的所以消息流动都是以WebSocketFrame来体现在handlerWebSocketFrame去处理消息,也可能是客户端发起的关闭指令,ping指令等等2.4 保存客户端的信息
当有客户端连接时候会被channelActive监听到,当断开时会被channelInactive监听到,一般在这两个方法中去保存/移除客户端的通道信息,而通道信息保存在ChannelSupervise中:
public class ChannelSupervise { private static ChannelGroup GlobalGroup=new DefaultChannelGroup(GlobalEventExecutor.INSTANCE); private static ConcurrentMap<String, ChannelId> ChannelMap=new ConcurrentHashMap(); public static void addChannel(Channel channel){ GlobalGroup.add(channel); ChannelMap.put(channel.id().asShortText(),channel.id()); } public static void removeChannel(Channel channel){ GlobalGroup.remove(channel); ChannelMap.remove(channel.id().asShortText()); } public static Channel findChannel(String id){ return GlobalGroup.find(ChannelMap.get(id)); } public static void send2All(TextWebSocketFrame tws){ GlobalGroup.writeAndFlush(tws); }}
ChannelGroup是netty提供用于管理web于服务器建立的通道channel的,其本质是一个高度封装的set集合,在服务器广播消息时,可以直接通过它的writeAndFlush将消息发送给集合中的所有通道中去。但在查找某一个客户端的通道时候比较坑爹,必须通过channelId对象去查找,而channelId不能人为创建,所有必须通过map将channelId的字符串和channel保存起来。
结尾
感谢看到最后的朋友,都看到最后了,点个赞再走啊,如有不对之处还请多多指正。