netty 学习记录一

最近在学习netty相关知识,觉得《netty 权威指南》这本书还是挺好的,适合我这种初学者.加上netty本身自带的许多例子,学起来还是挺有兴趣的.简单记录下,

一般服务器代码如下:

 public void run() throws Exception {
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, workerGroup)
             .channel(NioServerSocketChannel.class)
             .childHandler(new ChannelInitializer<SocketChannel>() {
                @Override
                public void initChannel(SocketChannel ch) throws Exception {
                    ch.pipeline().addLast(
                            new ObjectEncoder(),
                            new ObjectDecoder(ClassResolvers.cacheDisabled(null)),
                            new ObjectEchoServerHandler(),
                            new MyServerHandler());
                }
             });

            // Bind and start to accept incoming connections.
            b.bind(port).sync().channel().closeFuture().sync();
            
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }

EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workerGroup = new NioEventLoopGroup();

ServerBootstrap 是一个启动工具类,childHandler()方法用于往里面加入处理channel的操作类,并初始化它们. ChannelPipeline用于链式管理内部的channel处理类.

b.bind(port).sync().channel().closeFuture().sync();  这句话拆成下面两句好理解点:

b.bind(port).sync() ;  线程同步阻塞等待服务器绑定到指定端口,

...channel().closeFuture().sync() 成功绑定到端口之后,给channel增加一个 管道关闭的监听器并同步阻塞,直到channel关闭,线程才会往下执行,结束进程。