【Netty】01-服务端和客户端的搭建

为什么采用Netty，而不采用Nio

Nio原生Api很复杂

Nio存在epoll bug，会产生空轮询，导致cpu被占用100%

Netty是基于Nio进行包装，性能上会更高

Netty学习成本和使用成本更低

摘抄自其他文章， Netty的优点总结：

使用Netty创建服务器端

NettyServer

package com.itmayiedu.demo;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.LineBasedFrameDecoder;
import io.netty.handler.codec.string.StringDecoder;

/**
 * 搭建NettyServer
 *
 */
public class NettyServerDemo {
    static final int port = 8080;
    public static void main(String[] args) {
        // 1. 创建两个线程池，分别作为boss线程池和work线程池
        // boss线程池
        NioEventLoopGroup bossGroup = new NioEventLoopGroup();
        // work线程池
        NioEventLoopGroup workGroup = new NioEventLoopGroup();

        // 创建NettyServer
        ServerBootstrap serverBootstrap = new ServerBootstrap();
        // 将线程池加入到serverBootStrap中              设置为服务端： NioServerSocketChannel.class
        serverBootstrap.group(bossGroup, workGroup).channel(NioServerSocketChannel.class)
        // 添加消息处理
        .childHandler(new ChannelInitializer<SocketChannel>() {
            protected void initChannel(SocketChannel ch) throws Exception {
                ch.pipeline().addLast(new LineBasedFrameDecoder(1024));
                ch.pipeline().addLast(new StringEncoder());
                ch.pipeline().addLast(new ServerHandler());
            }
        });
        try{
            ChannelFuture channelFuture = serverBootstrap.bind(port);
            System.out.println("服务端已经启动，port： " + port);
            channelFuture.channel().closeFuture().sync();
        }catch(Exception e) {

        }finally {
            bossGroup.shutdownGracefully();
            workGroup.shutdownGracefully();

        }

    }
}

ServerHandler

package com.itmayiedu.demo;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.HttpRequest;
import io.netty.util.CharsetUtil;

public class ServerHandler extends SimpleChannelInboundHandler {

    /**
     * 服务端回复数据的方法
     * @param ctx
     * @throws Exception
     */
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        for (int i = 0; i < 10; i++) {
            ctx.writeAndFlush(Unpooled.copiedBuffer("每天学习一小时\n", CharsetUtil.UTF_8));
        }
    }

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

    // 读取消息的方法
    protected void channelRead0(ChannelHandlerContext ctx, Object msg) throws Exception {
        ByteBuf byteBuf = (ByteBuf) msg;
        if (msg instanceof HttpRequest) {
            String request = byteBuf.toString(CharsetUtil.UTF_8);
            System.out.println("服务端接收到消息：" + request);
        }


    }
}

使用Netty创建客户端

NettyClient

package com.itmayiedu.demo;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.LineBasedFrameDecoder;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;

import java.io.IOException;
import java.net.InetSocketAddress;

public class NettyClientDemo {
    public static void main(String[] args) throws IOException {
        NioEventLoopGroup group = new NioEventLoopGroup();
        Bootstrap bootstrap = new Bootstrap();
        bootstrap.group(group).channel(NioSocketChannel.class)
                .remoteAddress(new InetSocketAddress("127.0.0.1", 8080))
                .handler(new ChannelInitializer<SocketChannel>() {
                    protected void initChannel(SocketChannel ch) throws Exception {
                        ch.pipeline().addLast(new LineBasedFrameDecoder(1024));
                        ch.pipeline().addLast(new StringEncoder());
                        ch.pipeline().addLast(new ClientHandler());
                    }
                });
       try{
           ChannelFuture sync = bootstrap.connect().sync();
           sync.channel().closeFuture().sync();
       }catch (Exception e) {

       }finally {
           group.shutdownGracefully();
       }
    }
}

ClientHandler

package com.itmayiedu.demo;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.util.CharsetUtil;

public class ClientHandler extends SimpleChannelInboundHandler {


    /**
     * 发送消息的方法
     * @param ctx
     * @throws Exception
     */
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        for (int i = 0; i < 10; i++) {
            ctx.writeAndFlush(Unpooled.copiedBuffer("每天平均学习多久？\n", CharsetUtil.UTF_8));
        }
    }

    /**
     * 获取消息的方法
     * @param ctx
     * @param msg
     * @throws Exception
     */
    protected void channelRead0(ChannelHandlerContext ctx, Object msg) throws Exception {
        ByteBuf byteBuf = (ByteBuf) msg;
        String request = byteBuf.toString(CharsetUtil.UTF_8);
        System.out.println("客户端接收到消息: " + request);
    }
}