springboot+netty+redis框架服务端的实现（一） ------ pom依赖、netty配置类、自定义协议以及编解码器的实现

一、 pom.xml 所需依赖

MessagePack是编解码工具，稍后介绍

	    <!-- https://mvnrepository.com/artifact/io.netty/netty-all -->
	    <dependency>
	        <groupId>io.netty</groupId>
	        <artifactId>netty-all</artifactId>
	    </dependency>
	    
	    <!-- https://mvnrepository.com/artifact/org.msgpack/msgpack -->
	    <dependency>
	        <groupId>org.msgpack</groupId>
	        <artifactId>msgpack</artifactId>
	        <version>0.6.12</version>
	    </dependency>
	    
		<!-- Redis -->
	    <dependency>
	        <groupId>org.springframework.boot</groupId>
	        <artifactId>spring-boot-starter-data-redis</artifactId>
	    </dependency>

二、 netty配置类

2.1 启动服务类

创建两个EventLoopGroup实例，实际是两个Reactor线程组，一个用于服务端接收客户端的连接，一个用于进行socketChannel的网络读写
ServerBootstrap对象是netty用于启动NIO服务端的辅助启动类，目的是降低服务端的开发复杂度
group方法将两个NIO线程组当做入参传递到ServerBootstrap中
接着设置创建的Channel为NioServerSocketChannel
然后配置TCP参数，此处将他的backlog设置为128
然后绑定I/O事件的处理类ServerChannelInitializer，这个稍后看实现，主要用于处理网络I/O事件，例如对消息进行编解码、记录日志、处理业务等
可以通过childOption针对客户端进行一些配置，例如检测心跳状态、设置是否一次发送等

	private final EventLoopGroup bossGroup = new NioEventLoopGroup();
    private final EventLoopGroup workerGroup = new NioEventLoopGroup();
    
    private Channel channel;

    @Autowired
    private ChannelCache channelCachel;

	public ChannelFuture run(InetSocketAddress address) {
   

        ChannelFuture f = null;
        try {
   
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class).option(ChannelOption.SO_BACKLOG, 128)
                    .childHandler(new ServerChannelInitializer()).childOption(ChannelOption.SO_KEEPALIVE, true)
                    .childOption(ChannelOption.TCP_NODELAY, true);

            f = b.bind(address).sync();
            channel = f.channel();
        } catch (Exception e) {
   
            log.error("Netty start error:", e);
        } finally {
   
            if (f != null && f.isSuccess()) {
   
                log.info("Netty server listening " + address.getHostName() + " on port " + address.getPort()
                        + " and ready for connections...");
            } else {
   
                log.error("Netty server start up Error!");
            }
        }

        return f;
    }

2.2 netty退出

    public void destroy() {
   
        log.info("Shutdown Netty Server...");
        channelCachel.flushDb();
        if (channel != null) {
   
            channel.close();
        }
        workerGroup.shutdownGracefully();
        bossGroup.shutdownGracefully();
        log.info("Shutdown Netty Server Success!");
    }

其中channelCachel是自定义的一个保存通道信息的工具类，稍后介绍

2.3 I/O事件处理类

主要包括对消息的编解码、设置心跳超时以及设置业务处理类
本例中，服务端只检测读空闲时间
编解码器和业务处理类稍后展示

public class ServerChannelInitializer extends ChannelInitializer<SocketChannel> {
   

    @Override
    protected void initChannel(SocketChannel socketChannel) throws E