Netty入门之HelloWorld

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1.需求

客户端发送一个请求，服务端响应hello cxl

2.创建项目

1.maven依赖

	<dependency>
			<groupId>io.netty</groupId>
			<artifactId>netty-all</artifactId>
			<version>4.1.25.Final</version>
		</dependency>

2.创建主启动类

package com.cxl.netty;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.epoll.EpollEventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;

/**
 * 实现客户端发送一个请求，服务器会返回hello netty
 * @author mingliang
 *
 */
public class HelloServer {
	
	public static void main(String[] args) throws InterruptedException {
	
		//定义一对线程组
		//主线程组
		EventLoopGroup bossGroup = new NioEventLoopGroup();
		//从线程组
		EventLoopGroup workerGroup = new NioEventLoopGroup();
		
		try {
			//netty服务器的创建，ServerBootstrap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9099为启动的端口号，并且启动方式为同步
			ChannelFuture channelFuture = 
					serverBootstrap.bind(8082).sync(); //绑定端口，设置同步方式
			channelFuture.channel().closeFuture().sync();
		} finally {
			bossGroup.shutdownGracefully();
			workerGroup.shutdownGracefully();
		}

	}

}

3.创建初始化类

package com.cxl.netty;

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

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

	@Override
	protected void initChannel(SocketChannel channel) throws Exception {
		//通过SocketChannel去获取对应的管道
		ChannelPipeline pipeline = channel.pipeline();
		//通过管道，添加handler
		//HttpServerCodec 是netty提供的助手类，可以理解拦截器
		//当请求到服务端我们需要做编解码，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 cxl
		pipeline.addLast("customHandler",new CustomHandler());
		
	}

}

4.创建拦截器

package com.cxl.netty;

import java.nio.charset.Charset;
import java.nio.charset.CharsetEncoder;

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.HttpHeaders;
import io.netty.handler.codec.http.HttpObject;
import io.netty.handler.codec.http.HttpResponseStatus;
import io.netty.handler.codec.http.HttpStatusClass;
import io.netty.handler.codec.http.HttpVersion;
import io.netty.util.CharsetUtil;

/**
 *    自定义handler
 * @author mingliang
 *
 */
//SimpleChannelInboundHandler 相当于入站
public class CustomHandler extends SimpleChannelInboundHandler<HttpObject>{

	@Override
	protected void channelRead0(ChannelHandlerContext ctx, HttpObject msg) 
			throws Exception {
		Channel channel = ctx.channel();//获取当前channel
		System.out.println(channel.remoteAddress()); //显示客户端的远程地址
		//定义发送的数据消息
		ByteBuf content = Unpooled.copiedBuffer("Hello cxl",CharsetUtil.UTF_8);
		//构建一个http响应
		FullHttpResponse response =
				new DefaultFullHttpResponse
				(HttpVersion.HTTP_1_1,
						HttpResponseStatus.OK,
						content);
		
		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);
		
		
	}

}

3.启动main方法

页面发送请求即可