Netty3 Hello Word

Netty3 Hello Word

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概述

https://github.com/csy512889371/learndemo/netty/NettyHello

netty版本大致版本分为 netty3.x 和 netty4.x、netty5.x

netty可以运用在那些领域?

1、分布式进程通信

例如: hadoop、dubbo、akka等具有分布式功能的框架,底层RPC通信都是基于netty实现的,这些框架使用的版本通常都还在用netty3.x

2、游戏服务器开发

最新的游戏服务器有部分公司可能已经开始采用netty4.x 或 netty5.x

1、netty服务端hello world案例

SimpleChannelHandler 处理消息接收和写
{
	messageReceived接收消息

	channelConnected新连接,通常用来检测IP是否是黑名单

	channelDisconnected链接关闭,可以再用户断线的时候清楚用户的缓存数据等
}

2、netty客户端hello world案例

  • channelDisconnected与channelClosed的区别

  • channelDisconnected只有在连接建立后断开才会调用

  • channelClosed无论连接是否成功都会调用关闭资源

netty server 服务端

1、初始化ServerBootstrap,并注入NioServerSocketChannelFactory,用于创建通道(channel)等。从这里可以看出是通过Nio的方式来处理的,factory中放入两个线程池,主要用于接收connect和message。

2、MyHandler继承了SimpleChannelHandler,并且重写了方法:channelClosed、channelConnected、messageReseived,方法的参数为ChannelHandlerContext和ChannelEvent。ChannelHandlerContext为通道上下文,event中便带有消息和连接的信息。

  • channelConnected方法在接到来自客户端的连接时触发(这里只是打印了收到的连接的信息),所以在执行telnet命令时,看到控制台会有相应的输出。 MessageReseived方法在接收到消息是会触发,这里会交给processMessage方法处理,这里只是简单的把接收到的信息写回客户端。所以在命令行窗口中会看到我们写入的字母信息。

  • ChannelClosed方法在关闭连接的时候被调用,当我们关闭命令行窗口的时候,就会看到控制台打印出相应的信息。

  • 当然,ChannelHander的接口不止这么三个,除了SimpleChannelHandler以外还有很特殊的实现,这里只做简单介绍。

3、初始化完成之后,我们调用server.config(int port)方法注入需要绑定的端口信息

Server

import java.net.InetSocketAddress;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import org.jboss.netty.bootstrap.ServerBootstrap;
import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelPipelineFactory;
import org.jboss.netty.channel.Channels;
import org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory;
import org.jboss.netty.handler.codec.string.StringDecoder;
import org.jboss.netty.handler.codec.string.StringEncoder;

/**
 * netty服务端入门
 */
public class Server {

    public static void main(String[] args) {

        //服务类
        ServerBootstrap bootstrap = new ServerBootstrap();

        //boss线程监听端口,worker线程负责数据读写
        ExecutorService boss = Executors.newCachedThreadPool();
        ExecutorService worker = Executors.newCachedThreadPool();

        //设置niosocket工厂
        bootstrap.setFactory(new NioServerSocketChannelFactory(boss, worker));

        //设置管道的工厂
        bootstrap.setPipelineFactory(new ChannelPipelineFactory() {

            @Override
            public ChannelPipeline getPipeline() throws Exception {

                ChannelPipeline pipeline = Channels.pipeline();
                pipeline.addLast("decoder", new StringDecoder());
                pipeline.addLast("encoder", new StringEncoder());
                pipeline.addLast("helloHandler", new HelloHandler());
                return pipeline;
            }
        });

        bootstrap.bind(new InetSocketAddress(10101));

        System.out.println("start!!!");

    }

}

HelloHandler

import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelStateEvent;
import org.jboss.netty.channel.ExceptionEvent;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelHandler;

/**
 * 消息接受处理类
 */
public class HelloHandler extends SimpleChannelHandler {

    /**
     * 接收消息
     */
    @Override
    public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {


        String s = (String) e.getMessage();
        System.out.println(s);

        //回写数据
        ctx.getChannel().write("hi");
        super.messageReceived(ctx, e);
    }

    /**
     * 捕获异常
     */
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) throws Exception {
        System.out.println("exceptionCaught");
        super.exceptionCaught(ctx, e);
    }

    /**
     * 新连接
     */
    @Override
    public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
        System.out.println("channelConnected");
        super.channelConnected(ctx, e);
    }

    /**
     * 必须是链接已经建立,关闭通道的时候才会触发
     */
    @Override
    public void channelDisconnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
        System.out.println("channelDisconnected");
        super.channelDisconnected(ctx, e);
    }

    /**
     * channel关闭的时候触发
     */
    @Override
    public void channelClosed(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
        System.out.println("channelClosed");
        super.channelClosed(ctx, e);
    }
}

运行程序,打开命令行,输入:telnet 127.0.0.1 10101

netty client netty 客户端

import java.net.InetSocketAddress;
import java.util.Scanner;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import org.jboss.netty.bootstrap.ClientBootstrap;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelFuture;
import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelPipelineFactory;
import org.jboss.netty.channel.Channels;
import org.jboss.netty.channel.socket.nio.NioClientSocketChannelFactory;
import org.jboss.netty.handler.codec.string.StringDecoder;
import org.jboss.netty.handler.codec.string.StringEncoder;

/**
 * netty客户端入门
 */
public class Client {

    public static void main(String[] args) {

        //服务类
        ClientBootstrap bootstrap = new ClientBootstrap();

        //线程池
        ExecutorService boss = Executors.newCachedThreadPool();
        ExecutorService worker = Executors.newCachedThreadPool();

        //socket工厂
        bootstrap.setFactory(new NioClientSocketChannelFactory(boss, worker));

        //管道工厂
        bootstrap.setPipelineFactory(new ChannelPipelineFactory() {

            @Override
            public ChannelPipeline getPipeline() throws Exception {
                ChannelPipeline pipeline = Channels.pipeline();
                pipeline.addLast("decoder", new StringDecoder());
                pipeline.addLast("encoder", new StringEncoder());
                pipeline.addLast("hiHandler", new HiHandler());
                return pipeline;
            }
        });

        //连接服务端
        ChannelFuture connect = bootstrap.connect(new InetSocketAddress("127.0.0.1", 10101));
        Channel channel = connect.getChannel();

        System.out.println("client start");

        Scanner scanner = new Scanner(System.in);
        while (true) {
            System.out.println("请输入");
            channel.write(scanner.next());
        }
    }

}
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelStateEvent;
import org.jboss.netty.channel.ExceptionEvent;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelHandler;

/**
 * 消息接受处理类
 */
public class HiHandler extends SimpleChannelHandler {

    /**
     * 接收消息
     */
    @Override
    public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {


        String s = (String) e.getMessage();
        System.out.println(s);

        super.messageReceived(ctx, e);
    }

    /**
     * 捕获异常
     */
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) throws Exception {
        System.out.println("exceptionCaught");
        super.exceptionCaught(ctx, e);
    }

    /**
     * 新连接
     */
    @Override
    public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
        System.out.println("channelConnected");
        super.channelConnected(ctx, e);
    }

    /**
     * 必须是链接已经建立,关闭通道的时候才会触发
     */
    @Override
    public void channelDisconnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
        System.out.println("channelDisconnected");
        super.channelDisconnected(ctx, e);
    }

    /**
     * channel关闭的时候触发
     */
    @Override
    public void channelClosed(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
        System.out.println("channelClosed");
        super.channelClosed(ctx, e);
    }
}

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