Netty入门

Netty 开发环境搭建

• 安装JDK
• 下载Netty对应的jar包
• 搭建一个项目工程

Netty 服务端开发

package com.netty.study;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;

/**
 * netty server
 * @author yuxi
 */
public class NettyServer {
    public static void main(String[] args) {
        bind(8089);
    }

    /**
     * bind port
     * @param port
     */
    private static void bind(int port) {

        EventLoopGroup boss = new NioEventLoopGroup();
        EventLoopGroup worker = new NioEventLoopGroup();

        ServerBootstrap serverBootstrap = new ServerBootstrap();

        try {
            serverBootstrap.group(boss,worker)
                .channel(NioServerSocketChannel.class)
                .option(ChannelOption.SO_BACKLOG,1024)
                .childHandler(new ChildChannelHandler());

            ChannelFuture future = serverBootstrap.bind(port).sync();
            future.channel().closeFuture().sync();


        }catch (Exception e){

        }finally {
            boss.shutdownGracefully();
            worker.shutdownGracefully();
        }

    }

    private static class ChildChannelHandler extends ChannelInitializer {
        @Override
        protected void initChannel(SocketChannel socketChannel) {
            socketChannel.pipeline().addLast(new TimeServerHandler());
        }
    }
}

• 创建两个NIO线程组
• 创建ServerBootstrap，它是NIO服务端启动辅助类
• 启动参数配置
• 绑定I/O事件的处理类ChildChannelHandler

package com.netty.study;

import java.util.Date;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;

/**
 * @author yuxi
 */
public class TimeServerHandler extends ChannelHandlerAdapter {
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        super.exceptionCaught(ctx, cause);
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {

        ByteBuf byteBuf = (ByteBuf)msg;
        byte[] req = new byte[byteBuf.readableBytes()];
        byteBuf.readBytes(req);

        String body = new String(req,"utf-8");
        System.out.println("this is body:"+body);

        String currentTime = "ok".equals(body)?new Date(System.currentTimeMillis()).toString():
            "not ok";

        ByteBuf resp = Unpooled.copiedBuffer(currentTime.getBytes());
        ctx.writeAndFlush(resp);

    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
       ctx.flush();
    }
}

Netty 客户端开发

package com.netty.study;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;

/**
 * netty client
 * @author yuxi
 */
public class NettyClient {
    public static void main(String[] args) {
        connect("127.0.0.1",8089);
    }

    /**
     *
     * @param host
     * @param port
     */
    private static void connect(String host, int port) {
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            Bootstrap bootstrap = new Bootstrap();

            bootstrap.group(group)
                .channel(NioSocketChannel.class)
                .option(ChannelOption.TCP_NODELAY,true)
                .handler(new ChannelInitializer() {
                    @Override
                    protected void initChannel(SocketChannel socketChannel) throws Exception {
                    socketChannel.pipeline().addLast(new TimeClientHandler());
                    }
                });

            ChannelFuture channelFuture = bootstrap.connect(host, port);
            channelFuture.sync();

            channelFuture.channel().closeFuture().sync();

        }catch (Exception e){
        }finally {
            group.shutdownGracefully();

        }
    }
}

• 创建客户端处理I/O读写的线程组
• 创建客户端启动辅助类
• 启动参数配置
• 调研connect，发起异步连接

package com.netty.study;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;

public class TimeClientHandler extends ChannelHandlerAdapter {

    private final ByteBuf firstMessage;

    public TimeClientHandler() {
        byte[] req = "ok".getBytes();
        this.firstMessage = Unpooled.buffer(req.length);
        this.firstMessage.writeBytes(req);
    }

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

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
      ByteBuf byteBuf = (ByteBuf)msg;
      byte[] req = new byte[byteBuf.readableBytes()];
      byteBuf.readBytes(req);

      String body = new String(req,"utf-8");
      System.out.println("now is:"+body);
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
       ctx.writeAndFlush(firstMessage);
    }
}