Netty(一)快速入门实例

作者: 小左伯爵 | 来源:发表于2020-10-29 22:27 被阅读0次

1.实例要求

netty服务器监听8023端口，客户端发送消息给服务器：hello server，服务器回复：Did you say hello server?
依赖pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>cn.itbin</groupId>
    <artifactId>nettybase</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
            <version>4.1.28.Final</version>
        </dependency>
    </dependencies>


</project>

2.客户端代码

2.1 TelnetClient

package cn.itbin.client;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;

import java.io.BufferedReader;
import java.io.InputStreamReader;

/**
 * @author chenxiaogao
 * @className TelnetClient
 * @description TODO
 * @date 2020/10/29
 **/
public class TelnetClient {
    static final String HOST = System.getProperty("host", "127.0.0.1");
    static final int PORT = Integer.parseInt(System.getProperty("port", "8023"));

    public static void main(String[] args) throws Exception {

        EventLoopGroup group = new NioEventLoopGroup();
        try {
            Bootstrap b = new Bootstrap();
            b.group(group)
                    .channel(NioSocketChannel.class)
                    .handler(new TelnetClientInitializer());

            // 开始尝试连接
            Channel ch = b.connect(HOST, PORT).sync().channel();

            // 从控制台读取输入
            ChannelFuture lastWriteFuture = null;
            BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
            for (; ; ) {
                String line = in.readLine();
                if (line == null) {
                    break;
                }

                // 发送控制台的输入
                lastWriteFuture = ch.writeAndFlush(line + "\r\n");

                // 如果用户输入了bye,则在此等待直到服务端关闭连接
                if ("bye".equals(line.toLowerCase())) {
                    ch.closeFuture().sync();
                    break;
                }
            }

            // 等到所有消息都被flush后再关闭连接
            if (lastWriteFuture != null) {
                lastWriteFuture.sync();
            }
        } finally {
            group.shutdownGracefully();
        }
    }
}

2.2 TelnetClientInitializer

package cn.itbin.client;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.Delimiters;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;

/**
 * @author chenxiaogao
 * @className TelnetClientInitializer
 * @description TODO
 * @date 2020/10/29
 **/
public class TelnetClientInitializer extends ChannelInitializer<SocketChannel> {
    private static final StringDecoder DECODER = new StringDecoder();
    private static final StringEncoder ENCODER = new StringEncoder();

    private static final TelnetClientHandler CLIENT_HANDLER = new TelnetClientHandler();

    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();


        //首先添加文本行编解码器
        pipeline.addLast(new DelimiterBasedFrameDecoder(8192, Delimiters.lineDelimiter()));
        pipeline.addLast(DECODER);
        pipeline.addLast(ENCODER);

        //然后添加业务逻辑
        pipeline.addLast(CLIENT_HANDLER);

    }
}

2.3 TelnetClientHandler

package cn.itbin.client;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;

/**
 * @author chenxiaogao
 * @className TelnetClientHandler
 * @description TODO
 * @date 2020/10/29
 **/
public class TelnetClientHandler extends SimpleChannelInboundHandler<String> {
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        System.err.println(msg);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        cause.printStackTrace();
        ctx.close();
    }
}

3 服务端代码

3.1 TelnetServer

package cn.itbin.server;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import io.netty.handler.ssl.SslContext;
import io.netty.handler.ssl.SslContextBuilder;
import io.netty.handler.ssl.util.SelfSignedCertificate;

/**
 * Simplistic telnet server.
 */
public final class TelnetServer {

    static final int PORT = Integer.parseInt(System.getProperty("port", "8023"));

    public static void main(String[] args) throws Exception {

        EventLoopGroup bossGroup = new NioEventLoopGroup(1);
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, workerGroup)
             .channel(NioServerSocketChannel.class)
             .handler(new LoggingHandler(LogLevel.INFO))
             .childHandler(new TelnetServerInitializer());

            b.bind(PORT).sync().channel().closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

3.2 TelnetServerInitializer

package cn.itbin.server;

import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.Delimiters;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;

/**
 * @author chenxiaogao
 * @className TelnetServerInitializer
 * @description TODO
 * @date 2020/10/29
 **/
public class TelnetServerInitializer extends ChannelInitializer<SocketChannel> {
    private static final StringDecoder DECODER = new StringDecoder();
    private static final StringEncoder ENCODER = new StringEncoder();

    private static final TelnetServerHandler SERVER_HANDLER = new TelnetServerHandler();
    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();
        pipeline.addLast(new DelimiterBasedFrameDecoder(8192, Delimiters.lineDelimiter()));
        // 编解码器是静态的因为他们是可共享的
        pipeline.addLast(DECODER);
        pipeline.addLast(ENCODER);

        // 业务逻辑
        pipeline.addLast(SERVER_HANDLER);

    }
}

3.3 TelnetServerHandler

package cn.itbin.server;

import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;

import java.net.InetAddress;
import java.util.Date;

/**
 * @author chenxiaogao
 * @className TelnetServerHandler
 * @description TODO
 * @date 2020/10/29
 **/
public class TelnetServerHandler extends SimpleChannelInboundHandler<String> {

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        // 为新建的连接发送问候
        ctx.write("Welcome to " + InetAddress.getLocalHost().getHostName() + "!\r\n");
        ctx.write("It is " + new Date() + " now.\r\n");
        ctx.flush();
    }
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String request) throws Exception {
        // Generate and write a response.
        String response;
        boolean close = false;
        if (request.isEmpty()) {
            response = "Please type something.\r\n";
        } else if ("bye".equals(request.toLowerCase())) {
            response = "Have a good day!\r\n";
            close = true;
        } else {
            response = "Did you say '" + request + "'?\r\n";
        }

        // 不需要在这里写 ChannelBuffer.
        // 编码器在会将response做转换
        ChannelFuture future = ctx.write(response);

        // 在发送"Have a good day!\r\n"后关闭连接
        // 如果客户端发过来的是bye
        if (close) {
            future.addListener(ChannelFutureListener.CLOSE);
        }
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) {
        ctx.flush();
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        cause.printStackTrace();
        ctx.close();
    }
}

在客户端控制台输入hello server

Welcome to DESKTOP-39GQUQV!
It is Thu Oct 29 22:25:53 CST 2020 now.
hello server
Did you say 'hello server'?
bye
Have a good day!

Netty(一)快速入门实例

1.实例要求

2.客户端代码

2.1 TelnetClient

2.2 TelnetClientInitializer

2.3 TelnetClientHandler

3 服务端代码

3.1 TelnetServer

3.2 TelnetServerInitializer

3.3 TelnetServerHandler

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