netty创建socket连接

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
import io.netty.handler.codec.LengthFieldPrepender;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.util.CharsetUtil;

/**
 * @author 
 * @description 初始化服务端socket
 * @date 2019/4/23
 */
public class SocketServerInitializer extends ChannelInitializer {
    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();

        pipeline.addLast(new LengthFieldBasedFrameDecoder(Integer.MAX_VALUE,0,4,0,4));
        pipeline.addLast(new LengthFieldPrepender(4));
        //字符串解码
        pipeline.addLast(new StringDecoder(CharsetUtil.UTF_8));
        //字符串编码
        pipeline.addLast(new StringEncoder(CharsetUtil.UTF_8));
        //自己定义的处理器
        pipeline.addLast(new SocketServerHandler());
    }
}

SocketServerHandler 类 ：开启服务端socket连接

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

import java.util.UUID;

/**
 * @author 
 * @description 开启服务端socket连接
 * @date 2019/4/23
 */
public class SocketServerHandler extends SimpleChannelInboundHandler {

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        //打印出客户端地址
        System.out.println(ctx.channel().remoteAddress()+", "+msg);
        ctx.channel().writeAndFlush("服务端id: "+ UUID.randomUUID());
    }

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

TestSocketServer 类 main函数，在这启动服务端

import com.santai.service.socket.SocketServerInitializer;
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;

/**
 * @author 
 * @description
 * @date 2019/4/23
 */
public class TestSocketServer {
    public static void main(String[] args) throws Exception {
        //启动服务端
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup wokerGroup = new NioEventLoopGroup();

        try{
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            //在服务器端的handler()方法表示对bossGroup起作用，而childHandler表示对wokerGroup起作用
            serverBootstrap.group(bossGroup,wokerGroup).channel(NioServerSocketChannel.class)
                    .childHandler(new SocketServerInitializer());

            ChannelFuture channelFuture = serverBootstrap.bind(8899).sync();
            channelFuture.channel().closeFuture().sync();
        }finally {
            bossGroup.shutdownGracefully();
            wokerGroup.shutdownGracefully();
        }
    }
}

然后初始化客户端：
SocketClientInitializer 类初始化客户端socket

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
import io.netty.handler.codec.LengthFieldPrepender;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.util.CharsetUtil;

/**
 * @author 
 * @description 初始化客户端socket
 * @date 2019/4/23
 */
public class SocketClientInitializer extends ChannelInitializer {
    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();

        pipeline.addLast(new LengthFieldBasedFrameDecoder(Integer.MAX_VALUE,0,4,0,4));
        pipeline.addLast(new LengthFieldPrepender(4));
        pipeline.addLast(new StringDecoder(CharsetUtil.UTF_8));
        pipeline.addLast(new StringEncoder(CharsetUtil.UTF_8));
        pipeline.addLast(new SocketClientHandler());
    }
}

SocketClientHandler类：开启客户端socket连接

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

import java.time.LocalDateTime;

/**
 * @author suntao
 * @description 开启客户端socket连接
 * @date 2019/4/2
 */
public class SocketClientHandler extends SimpleChannelInboundHandler {

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        //服务端的远程地址
        System.out.println(ctx.channel().remoteAddress());
        System.out.println("客户端日志: "+msg);
        ctx.writeAndFlush("来自客户端: "+ LocalDateTime.now());
    }

    /**
     * 当服务器端与客户端进行建立连接的时候会触发，如果没有触发读写操作，则客户端和客户端之间不会进行数据通信，也就是channelRead0不会执行，
     * 当通道连接的时候，触发channelActive方法向服务端发送数据触发服务器端的handler的channelRead0回调，然后
     * 服务端向客户端发送数据触发客户端的channelRead0，依次触发。
     */
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        ctx.writeAndFlush("来自与客户端的问题!");
    }

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

TestSocketClient类： main函数，在这启动客户端

import com.santai.service.socket.SocketClientInitializer;
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;

/**
 * @author 
 * @description
 * @date 2019/4/23
 */
public class TestSocketClient {
    public static void main(String[] args) throws Exception{
        //客户端启动连接
        EventLoopGroup eventLoopGroup = new NioEventLoopGroup();
        try{
            Bootstrap bootstrap = new Bootstrap();
            bootstrap.group(eventLoopGroup).channel(NioSocketChannel.class)
                    .handler(new SocketClientInitializer());

            ChannelFuture channelFuture = bootstrap.connect("localhost",8899).sync();
            channelFuture.channel().closeFuture().sync();
        }finally {
            eventLoopGroup.shutdownGracefully();
        }
    }
}