Netty入门（一）

jdk强迫你必须用socket来写服务器，实际上是很繁琐的。缺乏一个高层次的api。
netty说，我来写jdk的socket，并给你一个新的更简洁的api，你傻瓜式的就能写好一个网络服务器（而且是event-driven/proactor/reactor等等）。
当然，netty通过jni，引入了epoll这样的linux系统调用，使得它不单单是jdk的一个简单包裹，的确也加了些东西进去

/*   repositories {
        maven {url 'http://maven.aliyun.com/nexus/content/groups/public/'}
        mavenLocal()
        mavenCentral()
    }*/
 compile (group: 'io.netty', name: 'netty-all', version: '4.1.25.Final')

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.string.StringDecoder;

import java.net.InetSocketAddress;

/**
 * @author tanoak@qq.com
 * @date 2018/6/26 22:46
 * @Desc
 */
public class NettyServer {
    // 端口号
    private final int port;
    public NettyServer(int port) {
        this.port = port;
    }

    public void start() throws Exception {
        ServerBootstrap serverBootstrap = new ServerBootstrap();//① 是一个启动NIO服务的辅助启动类
        NioEventLoopGroup worker = new NioEventLoopGroup();//②NioEventLoopGroup是用来处理IO操作的多线程事件循环器
        serverBootstrap
                .group(worker)
                .channel(NioServerSocketChannel.class)
                .childHandler(new ChannelInitializer<NioSocketChannel>() {
                    @Override
                    protected void initChannel(NioSocketChannel ch) {
                        ch.pipeline().addLast(new StringDecoder());
                        ch.pipeline().addLast(new SimpleChannelInboundHandler<String>() {
                            //读取客户端发送的消息
                            @Override
                            protected void channelRead0(ChannelHandlerContext ctx, String msg) {
                                System.out.println("【客户端发送的消息】"+msg);
                            }
                        });
                    }
                })
                .bind(port);
    }

    public static void main(String[] args) throws Exception {
        try {
            new NettyServer( 8088).start();
            System.out.println("启动成功");
        }catch (Exception e){
            System.out.println("启动失败");
        }
    }
}

import com.tanoak.demo1.client.EchoClientHandler;
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.string.StringEncoder;

import java.net.InetSocketAddress;
import java.time.LocalDateTime;
import java.util.Date;

/** 
 * @author tanoak@qq.com
 * @date 2018/6/25 0:46
 * @Desc
 */ 
public class NettyClient {
    private final String host;
    private final int port;
    public NettyClient(String host, int port) {
        this.host = host;
        this.port = port;
    }

    public void start() throws Exception {
        Bootstrap bootstrap = new Bootstrap();
        NioEventLoopGroup group = new NioEventLoopGroup();
        bootstrap.group(group)
                .channel(NioSocketChannel.class)
                .handler(new ChannelInitializer<Channel>() {
                    @Override
                    protected void initChannel(Channel ch) {
                        ch.pipeline().addLast(new StringEncoder());
                    }
                });
        Channel channel = bootstrap.connect(host, port).channel();
        while (true) {
            channel.writeAndFlush("现在时间："+LocalDateTime.now());
            Thread.sleep(2000);
        }
    }

    public static void main(String[] args) throws Exception {
        new NettyClient("127.0.0.1",8088 ).start();
    }
}