netty005之Netty的Socket簡單例子

hadler往往決定了服務的類型

 

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;

/**
 * 服務端
 * 是什麼服務是childHandler決定即MyServerInitializer決定
 */
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<SocketChannel> {
    @Override
    protected void initChannel(SocketChannel socketChannel) throws Exception {
        ChannelPipeline pipeline = socketChannel.pipeline();
        //加入handler決定服務器的類型
        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的泛型決定了，消息的類型

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

import java.util.UUID;

public class MyServerHandler extends SimpleChannelInboundHandler<String> {
    /**
     *  必須客戶端發起請求時纔會觸發
     *  extends SimpleChannelInboundHandler<String>的泛型String和參數s的類型是一樣的
     * @param channelHandlerContext 通過它可以獲取連接信息，給客戶端發送信息
     * @param msg 就是接受客戶端的消息
     * @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();
    }
}

 

客戶端（一樣的套路）

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<SocketChannel> {
    @Override
    protected void initChannel(SocketChannel socketChannel) throws Exception {
        ChannelPipeline pipeline = socketChannel.pipeline();
        //加入handler決定了服務的類型
        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));
        //自定義hanlder
        pipeline.addLast(new MyClientHandler());
    }
}

 

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

import java.time.LocalDateTime;

public class MyClientHandler extends SimpleChannelInboundHandler<String> {

    /**
     * 必須服務端發起請求數據，纔會觸發
     * 客戶端與服務端通信的地方
     * @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);
        //給服務端發消息
        channelHandlerContext.writeAndFlush("from client:" + LocalDateTime.now());

    }


    /**
     *
     * @param ctx
     * @throws Exception
     */
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception{
        //沒有此句，服務端和客戶端都收不到消息
        ctx.writeAndFlush("來自於客戶端的問候，我激活的客戶端與服務端通信");
    }
}

三、通過端口查看現象