Hello Netty服务器

构建一堆主从线程组

定义服务器启动类

为服务器设置Channel

设置处理从线程池的助手类初始化器

监听启动和关闭服务器

 

/**
 * 实现客户端发送一个请求，服务器返回hello netty
 */

public class HelloServer {
    public static void main(String[] args) throws InterruptedException {
        //定义一对线程组
        //主线程组，用于接收客户端连接，但不做任何处理，跟老板一样，不做事
        EventLoopGroup bossGroup = new NioEventLoopGroup();

        //从线程组，老板线程组会把任务丢给他，让手下线程组去做任务
        EventLoopGroup workerGroup = new NioEventLoopGroup();

        try {
            //netty服务器的创建，serverBootstrap是一个启动类
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(bossGroup, workerGroup)    //设置主从线程组
                    .channel(NioServerSocketChannel.class)   //设置nio的双向通道
                    .childHandler(new HelloServerInitializer());                     //子处理器，用于处理workGroup

            //启动server,并且设置8088为启动的端口号，同时启动方式为同步
            ChannelFuture channelFuture = serverBootstrap.bind(8088).sync();

            //监听关闭的channel,设置为同步方式
            channelFuture.channel().closeFuture().sync();
        }finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

/**
 * 初始化器，channel注册后，会执行里面相应的初始化方法
 */
public class HelloServerInitializer extends ChannelInitializer<SocketChannel> {
    protected void initChannel(SocketChannel channel) throws Exception {
        //通过SocketChannel去获得对应的管道
       ChannelPipeline pipeline =  channel.pipeline();

       //通过管道，添加Handler
        //HttpServerCodec是由netty自己提供的助手类，可以理解为拦截器
        //当请求到服务器，我们需要做解码，响应到客户端做编码
       pipeline.addLast("HttpServerCodec", new HttpServerCodec());

       //添加自定义的助手类，返回"hello netty~"
       pipeline.addLast("customHandler", new CustomHandler());
    }
}

/**
 * 创建自定义助手类
 */
//SimpleChannelInboundHandler:对于请求来讲，其实相当于[入站，入境]
public class CustomHandler extends SimpleChannelInboundHandler<HttpObject> {
    protected void channelRead0(ChannelHandlerContext ctx, HttpObject msg) throws Exception {
       //获取channal
        Channel channel = ctx.channel();

        if(msg instanceof  HttpRequest){
            //显示客户端的远程地址
            System.out.println(channel.remoteAddress());

            //定义发送的数据消息
            ByteBuf content = Unpooled.copiedBuffer("Hello netty", CharsetUtil.UTF_8);

            //构建一个http response
            FullHttpResponse response =
                    new DefaultFullHttpResponse(HttpVersion.HTTP_1_1,
                            HttpResponseStatus.OK,
                            content);
            //为响应增加数据类型和长度
            response.headers().set(HttpHeaderNames.CONTENT_TYPE, "text/plain");
            response.headers().set(HttpHeaderNames.CONTENT_LENGTH, content.readableBytes());

            //把响应刷到客户端
            ctx.writeAndFlush(response);
        }
    }

    @Override
    public void channelRegistered(ChannelHandlerContext ctx) throws Exception {
        System.out.println("channal ... 注册");
        super.channelRegistered(ctx);
    }

    @Override
    public void channelUnregistered(ChannelHandlerContext ctx) throws Exception {
        System.out.println("channel ..... 移除");
        super.channelUnregistered(ctx);
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("channel ....活跃");
        super.channelActive(ctx);
    }

    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("channel .... 不活跃");
        super.channelInactive(ctx);
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
        System.out.println("channel 读取完毕.....");
        super.channelReadComplete(ctx);
    }

    @Override
    public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
        System.out.println("用户事件触发......");
        super.userEventTriggered(ctx, evt);
    }

    @Override
    public void channelWritabilityChanged(ChannelHandlerContext ctx) throws Exception {
        System.out.println("channel 可写更改");
        super.channelWritabilityChanged(ctx);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
       System.out.println("捕获到异常");
        super.exceptionCaught(ctx, cause);
    }

    @Override
    public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
        System.out.println("助手类添加");
        super.handlerAdded(ctx);
    }

    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
        System.out.println("助手类移除");
        super.handlerRemoved(ctx);
    }
}