Netty 入门案例源码+注释

Love The Way You Lie 2022-03-26 07:43 251阅读 0赞

1.创建maven项目，引入Netty 依赖

<dependency>
              <groupId>io.netty</groupId>
              <artifactId>netty-all</artifactId>
              <version>4.1.32.Final</version>
    </dependency>

2.项目结构  
![在这里插入图片描述][2019011611091141.png]

3.编写HelloNettyServer

import io.netty.bootstrap.ServerBootstrap;
    
    import io.netty.channel.ChannelFuture;
    import io.netty.channel.EventLoopGroup;
    import io.netty.channel.nio.NioEventLoopGroup;
    import io.netty.channel.socket.nio.NioServerSocketChannel;
    
    public class HelloNettyServer {
        public static void main(String[] args) throws InterruptedException {
    
                //创建一对线程组，
    
                //定义主线程，用于接受客户端的连接，但是不会做任何处理，跟老板一样，不做事。
                EventLoopGroup bossGroup = new NioEventLoopGroup();
                //定义从线程，老板线程组会把任务给它，让手下去做。
                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)  //设置主从线程类
                .channel(NioServerSocketChannel.class)        //设置nio的双向通道
                .childHandler(new HelloServerInitializer()); //子处理器，用于处理workerGroup
    
                //启动server，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();
            }
        }
    }

4.编写HelloServerInitializer

import io.netty.channel.Channel;
    import io.netty.channel.ChannelInitializer;
    import io.netty.channel.ChannelPipeline;
    import io.netty.handler.codec.http.HttpServerCodec;
    
    /*
    * 这是一个初始化器，当channel注册后，W
    * 会执行里面的相应的初始化方法。
    * */
    public class HelloServerInitializer extends ChannelInitializer {
    
        @Override
        protected void initChannel(Channel channel) throws Exception {
            //通过SocketChannel 去获取相应的管道
            ChannelPipeline pipeline = channel.pipeline();
            // 通过管道添加handler
            //httpServerCodec 是由netty自己提供助手类，可以理解为拦截器
            //当请求到服务器，我们需要解码，相应到客户端做编码
            pipeline.addLast("HttpServerCodec",new HttpServerCodec());
            //添加自定义的助手类，返回hello,netty
            pipeline.addLast("customHandler",new CustomHandler());
    
        }
    }

5.编写CustomHandler

/*
    * 创建自动一助手类
    * */
    
    import io.netty.buffer.ByteBuf;
    import io.netty.buffer.Unpooled;
    import io.netty.channel.Channel;
    import io.netty.channel.ChannelHandlerContext;
    import io.netty.channel.SimpleChannelInboundHandler;
    import io.netty.handler.codec.http.*;
    import io.netty.util.CharsetUtil;
    
    //SimpleChannelInboundHandler:对于请求来说，其实相当于[入栈，入境]
    public class CustomHandler extends SimpleChannelInboundHandler<HttpObject> {
    
        @Override
        protected void channelRead0(ChannelHandlerContext ctx, HttpObject msg) throws Exception {
            //获取Channel
            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);
                //为相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());
    
                //把相应到刷到相应的客户端
                ctx.writeAndFlush(response);
            }
    
    
        }
    }

6.测试  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2MTQxMzY5_size_16_color_FFFFFF_t_70]  
成功！

[2019011611091141.png]: /images/20220326/726e78c08cde479daab88653e4558b47.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2MTQxMzY5_size_16_color_FFFFFF_t_70]: /images/20220326/be0cf0f8fd064f7b9e1a5a311b2e2a93.png