netty005之Netty的Socket简单例子

hadler往往决定了服务的类型

 

一、server端

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;

/**
 * 服务端
 * 是什么服务是childHandler决定即MyServerInitializer决定
 */
public class MyServer {
    public static void main(String[] args) throws InterruptedException {
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();

        try {
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(bossGroup,workerGroup).channel(NioServerSocketChannel.class).childHandler(new MyServerInitializer());
            ChannelFuture channelFuture = serverBootstrap.bind(8888).sync();
            channelFuture.channel().closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }


    }
}

ChannelInitializer channel初始化

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;

public class MyServerInitializer extends ChannelInitializer {
    @Override
    protected void initChannel(SocketChannel socketChannel) throws Exception {
        ChannelPipeline pipeline = socketChannel.pipeline();
        //加入handler决定服务器的类型
        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 MyServerHandler());


    }
}

handler的泛型决定了，消息的类型

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

import java.util.UUID;

public class MyServerHandler extends SimpleChannelInboundHandler {
    /**
     *  必须客户端发起请求时才会触发
     *  extends SimpleChannelInboundHandler的泛型String和参数s的类型是一样的
     * @param channelHandlerContext 通过它可以获取连接信息，给客户端发送信息
     * @param msg 就是接受客户端的消息
     * @throws Exception
     */
    @Override
    protected void channelRead0(ChannelHandlerContext channelHandlerContext, String msg) throws Exception {
        System.out.println(channelHandlerContext.channel().remoteAddress() + ". \t"+ msg);
        channelHandlerContext.channel().writeAndFlush("from server msg " + UUID.randomUUID());

    }

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

 

客户端（一样的套路）

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;

public class MyClient {
    public static void main(String[] args) {
      EventLoopGroup eventLoopGroup = new NioEventLoopGroup();

        try {
            Bootstrap bootstrap = new Bootstrap();
            bootstrap.group(eventLoopGroup).channel(NioSocketChannel.class).handler(new MyClientInitializer());
            ChannelFuture channelFuture = bootstrap.connect("localhost", 8888).sync();
            channelFuture.channel().closeFuture().sync();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            eventLoopGroup.shutdownGracefully();

        }

    }
}

 

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;

public class MyClientInitializer extends ChannelInitializer {
    @Override
    protected void initChannel(SocketChannel socketChannel) throws Exception {
        ChannelPipeline pipeline = socketChannel.pipeline();
        //加入handler决定了服务的类型
        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));
        //自定义hanlder
        pipeline.addLast(new MyClientHandler());
    }
}

 

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

import java.time.LocalDateTime;

public class MyClientHandler extends SimpleChannelInboundHandler {

    /**
     * 必须服务端发起请求数据，才会触发
     * 客户端与服务端通信的地方
     * @param channelHandlerContext
     * @param msg
     * @throws Exception
     */
    @Override
    protected void channelRead0(ChannelHandlerContext channelHandlerContext, String msg) throws Exception {
        System.out.println(channelHandlerContext.channel().remoteAddress());
        System.out.println("client receive:" + msg);
        //给服务端发消息
        channelHandlerContext.writeAndFlush("from client:" + LocalDateTime.now());

    }


    /**
     *
     * @param ctx
     * @throws Exception
     */
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception{
        //没有此句，服务端和客户端都收不到消息
        ctx.writeAndFlush("来自于客户端的问候，我激活的客户端与服务端通信");
    }
}

三、通过端口查看现象