netty入门HttpServer实例

package com.soleil.netty;

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;

/**
 * @Description: 实现客户端发送一个请求，服务器会返回 hello netty
 */
public class HelloServer {
   public static void main(String[] args) throws Exception {
      // 定义一对线程组
      // 主线程组, 用于接受客户端的连接，但是不做任何处理，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workerGroup
         // 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，设置位同步方式
         channelFuture.channel().closeFuture().sync();
      } finally {
         bossGroup.shutdownGracefully();
         workerGroup.shutdownGracefully();
      }
   }
}

package com.soleil.netty;

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.http.HttpServerCodec;

/**
 * @Description: 初始化器，channel注册后，会执行里面的相应的初始化方法
 */
public class HelloServerInitializer extends ChannelInitializer<SocketChannel> {

   @Override
   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***
      // 当请求到服务端，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());
   }
}

package com.soleil.netty;

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.DefaultFullHttpResponse;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http.HttpHeaderNames;
import io.netty.handler.codec.http.HttpObject;
import io.netty.handler.codec.http.HttpRequest;
import io.netty.handler.codec.http.HttpResponseStatus;
import io.netty.handler.codec.http.HttpVersion;
import io.netty.util.CharsetUtil;

/**
 * @Description: 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> {

   @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("channel。。。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("channeld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);
   }

}