Netty的基本使用 Netty的基本使用

Netty的基本使用目录 [TOC]
引用

implementation 'io.netty:netty-all:4.1.6.Final'

Netty 4最后一个release版本是4.1.28,但是亲测这个版本启动就会报异常...........所以降级回4.1.6
使用 TCP
服务端

EventLoopGroup boss = new NioEventLoopGroup(); EventLoopGroup worker = new NioEventLoopGroup(); try { ServerBootstrap bootstrap = new ServerBootstrap(); bootstrap.group(boss, worker); bootstrap.channel(NioServerSocketChannel.class); bootstrap.option(ChannelOption.TCP_NODELAY, true); bootstrap.childOption(ChannelOption.SO_KEEPALIVE, true); bootstrap.childHandler(new ChannelInitializer() { @Override protected void initChannel(SocketChannel socketChannel) throws Exception { ChannelPipeline p = socketChannel.pipeline(); p.addLast("framedecoder", new LengthFieldBasedFrameDecoder(1024 * 1024 * 10, 0, 4, 0, 4)); p.addLast(new NettyServerHandler()); } }); mChannelFuture = bootstrap.bind(mPort).sync(); if (mChannelFuture.isSuccess()) { System.out.printf("start tcp server succeed,mPort : " + mPort); } mChannelFuture.channel().closeFuture().sync(); } catch (Exception e) { System.out.printf("a exception happened while tcp server running"); e.printStackTrace(); } finally { boss.shutdownGracefully(); worker.shutdownGracefully(); mIsRunning = false; }

其中

mChannelFuture.channel().closeFuture().sync();

会阻塞线程,所以这段代码应该放在一个线程中.
Channel是连接服务端和客户端的通道.

ChannelPipeline p = socketChannel.pipeline();

ChannelPipeline是一个处理器容器,当有新数据接收时会调用容器中的处理器.
【Netty的基本使用】NettyServerHandler是处理最终接收到数据的地方

private class NettyServerHandler extends ChannelInboundHandlerAdapter {@Override public void channelActive(ChannelHandlerContext ctx) throws Exception { initTransport(ctx.channel()); }@Override public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception { WrapPacket packet = SocketUtils.decodeWrapPacketFromByteBufAfterSplit((ByteBuf) msg); String channelId = ctx.channel().id().asLongText(); SubTransport transport = mChannelTransportMap.get(channelId); if (transport == null) { throw new RuntimeException("can not get transport form map , create a transport and put to map"); } transport.onNewPacketReceived(packet); }}

LengthFieldBasedFrameDecoder是基于包长度的包解析器,用来拆包和处理半包.还有其他的自带解析器,比如分割,固定包长度等,不过个人偏向于喜欢这个,这个可以将资源利用最大化,而且没有字符不能使用的限制,如果是分割符的解析器,则会占用掉一些字符组合不能使用.当然这个也会翻车,当别人恶意攻击时,或者协议设计有问题时,一个错了,那就接下来所有都错了.错一步,满盘皆输,也是渗人.当然也可以自定义包解析器喽.
客户端

EventLoopGroup eventLoopGroup = new NioEventLoopGroup(); try { Bootstrap bootstrap = new Bootstrap(); bootstrap.channel(NioSocketChannel.class); bootstrap.option(ChannelOption.SO_KEEPALIVE, true); bootstrap.group(eventLoopGroup); bootstrap.remoteAddress(mAddress, mPort); bootstrap.handler(new ChannelInitializer() { @Override protected void initChannel(SocketChannel socketChannel) throws Exception { socketChannel.pipeline().addLast("framedecoder", new LengthFieldBasedFrameDecoder(1024 * 1024 * 10, 0, 4, 0, 0)); socketChannel.pipeline().addLast(new NettyClientHandler()); } }); mChannelFuture = bootstrap.connect(mAddress, mPort).sync(); if (mChannelFuture.isSuccess()) { Log.d("connect to mAddress : " + mAddress + ", mPort : " + mPort + " succeed"); } mChannelFuture.channel().closeFuture().sync(); } catch (InterruptedException e) { e.printStackTrace(); Log.d("can not connect to mAddress : " + mAddress + " ,mPort : " + mPort); } finally { eventLoopGroup.shutdownGracefully(); }

同样也是阻塞的,和服务端差不多,便不再说明.
未完待续 ......