netty创建tcp (使用maven构建)

一、环境

java 版本 1.8.0_181

二、项目结构

项目结构如下图所示

image.png

三、导入必要的依赖

以下是pom.xml的配置

    4.0.0

    netty_tcp_test
    netty_tcp_test
    1.0-SNAPSHOT

    
        4.1.25.Final
        linux-x86_64
    

    
        
        
            io.netty
            netty-codec
            ${netty.version}
        
        
            io.netty
            netty-transport
            ${netty.version}
        
        
            io.netty
            netty-transport-native-epoll
            ${netty.version}
            ${os.detected.classifier}
        
        
            junit
            junit
            4.12
            test
        
        
            io.netty
            netty-codec-http
            ${netty.version}
        
        
            io.netty
            netty-handler
            ${netty.version}
        
        
            io.netty
            netty-transport-udt
            ${netty.version}
        
        
            io.netty
            netty-transport-sctp
            ${netty.version}
        

    

三、创建客户端代码

TcpClient的 main代码

package tcp;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
import io.netty.handler.codec.LengthFieldPrepender;
import io.netty.handler.codec.serialization.ClassResolvers;
import io.netty.handler.codec.serialization.ObjectDecoder;
import io.netty.handler.codec.serialization.ObjectEncoder;
import org.omg.PortableServer.POA;

public class TcpClient {

    public static String HOST = "127.0.0.1";

    public static int PORT = 12340;

    public static Bootstrap bootstrap=getBootstrap();

    public static Channel channel = getChannel(HOST,PORT);

    public static final Bootstrap getBootstrap(){
        EventLoopGroup group = new NioEventLoopGroup();
        Bootstrap bootstrap = new Bootstrap();
        bootstrap.group(group).channel(NioSocketChannel.class);
        bootstrap.handler(new ChannelInitializer() {
            @Override
            protected void initChannel(Channel ch) throws Exception{

                ChannelPipeline pipeline = ch.pipeline();
                pipeline.addLast("frameDecoder",new LengthFieldBasedFrameDecoder(Integer.MAX_VALUE,0,4,0,4));
                pipeline.addLast("frameEncoder",new LengthFieldPrepender(4));
                pipeline.addLast(new ObjectEncoder());
                pipeline.addLast(new ObjectDecoder(ClassResolvers.cacheDisabled(null)));
                pipeline.addLast("handler",new TcpClientHandler());
            }
        });
        bootstrap.option(ChannelOption.SO_KEEPALIVE,true);
        return bootstrap;
    }

    public static final Channel getChannel(String HOST, int PORT){
        Channel channel = null;
        try{
            channel = bootstrap.connect(HOST,PORT).sync().channel();
            System.out.println("连接成功");
        }catch (Exception e){
            System.out.println("连接server(IP{},PROT{})失败");
            return null;
        }
        return channel;
    }

    public static void sendMsg(Object msg) throws Exception{
        if(channel!=null){
            channel.writeAndFlush(msg).sync();
        }else{
            System.out.println("消息发送失败，连接尚未建立");
        }
    }

}

处理器TcpClientHandler代码

package tcp;

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

public class TcpClientHandler extends SimpleChannelInboundHandler