netty 入门

package time.server.impl;

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;

/**
 * TODO
 * 
 * @description
 * @author mjorcen
 * @time 2015年5月25日 下午2:50:57
 */
public class NTimeServerImpl {

    public void bind(int port) {
        // 创建两个NioEventLoopGroup 实例,NioEventLoopGroup
        // 是一个线程组,它包含一组NIO线程,专门用于处理网络事件的处理,实际上他们就是Reactor 线程组
        // 这里创建两个的原因是一个用于服务端接收用户的链接,另一个用于进行SocketChannel的网络读写
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();

        try {
            // 创建一个 ServerBootstrap ,它是netty用于NIO服务端的辅助启动类,目的是降低服务端的开发复杂度.
            ServerBootstrap bootstrap = new ServerBootstrap();
            // 设定 服务端接收用户请求的线程组和用于进行SocketChannel网络读写的线程组
            bootstrap.group(bossGroup, workerGroup);
            // 设置创建的 channel 类型
            bootstrap.channel(NioServerSocketChannel.class);
            // 配置 NioServerSocketChannel 的 tcp 参数, BACKLOG 的大小
            bootstrap.option(ChannelOption.SO_BACKLOG, 1024);
            // 绑定io处理类（childChannelHandler）.他的作用类似于 reactor 模式中的 handler
            // 类,主要用于处理网络 I/O 事件,例如对记录日志,对消息进行解码等.
            bootstrap.childHandler(new ChannelInitializer<SocketChannel>() {
                protected void initChannel(SocketChannel ch) throws Exception {
                    ch.pipeline().addLast(new TimeServerHandler());
                }
            });
            // 绑定端口,随后调用它的同步阻塞方法 sync 等等绑定操作成功,完成之后 Netty 会返回一个 ChannelFuture
            // 它的功能类似于的 Future,主要用于异步操作的通知回调.
            ChannelFuture channelFuture = bootstrap.bind(port).sync();
            // 等待服务端监听端口关闭,调用 sync 方法进行阻塞,等待服务端链路关闭之后 main 函数才退出.
            channelFuture.channel().closeFuture().sync();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            // 优雅的退出,释放线程池资源
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }

    public static void main(String[] args) {
        NTimeServerImpl server = new NTimeServerImpl();
        server.bind(9091);
    }

}

package time.server.impl;

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

import java.util.Date;

import time.TimeConfig;

/**
 * TODO
 *
 * @description
 * @author ez
 * @time 2015年5月25日 下午3:06:09
 */
public class TimeServerHandler extends ChannelHandlerAdapter implements
        TimeConfig {

    /*
     * (non-Javadoc)
     * 
     * @see io.netty.channel.ChannelHandlerAdapter#channelRead(io.netty.channel.
     * ChannelHandlerContext, java.lang.Object)
     */
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg)
            throws Exception {
        ByteBuf buf = (ByteBuf) msg;
        byte[] req = new byte[buf.readableBytes()];
        buf.readBytes(req);
        String body = new String(req, "utf-8");
        System.out.println("The time server receive order : " + body);
        String currentTime = QUERY.equalsIgnoreCase(body) ? new Date()
                .toString() : "BAD ORDER";
        System.out.println("currentTime : " + currentTime);
        ByteBuf resp = Unpooled.copiedBuffer(currentTime.getBytes("utf-8"));
        ctx.writeAndFlush(resp);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
            throws Exception {
        // 当出现异常时,释放资源.
        ctx.close();
    }

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

}

package time.client.impl;

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;

/**
 * TODO
 * 
 * @description
 * @author ez
 * @time 2015年5月25日 下午3:17:29
 */
public class NTimeClient {

    public void connect(int port, String host) throws Exception {
        EventLoopGroup group = new NioEventLoopGroup();
        try {

            Bootstrap bootstrap = new Bootstrap();
            bootstrap.group(group);
            bootstrap.channel(NioSocketChannel.class);
            bootstrap.option(ChannelOption.TCP_NODELAY, true);
            bootstrap.handler(new ChannelInitializer<SocketChannel>() {

                @Override
                protected void initChannel(SocketChannel ch) throws Exception {
                    ch.pipeline().addLast(new TimeClientHandler());
                }
            });

            // 发起异步链接操作
            ChannelFuture future = bootstrap.connect(host, port).sync();

            // 等待客户端链路关闭
            future.channel().closeFuture().sync();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            group.shutdownGracefully();
        }
    }

    public static void main(String[] args) throws Exception {
        NTimeClient client = new NTimeClient();
        client.connect(9091, "localhost");
    }
}

package time.client.impl;

import java.io.UnsupportedEncodingException;

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

/**
 * TODO
 *
 * @description
 * @author ez
 * @time 2015年5月25日 下午3:21:26
 */
public class TimeClientHandler extends ChannelHandlerAdapter implements
        TimeConfig {
    private final ByteBuf message;

    public TimeClientHandler() throws UnsupportedEncodingException {
        byte[] bs = QUERY.getBytes("utf-8");
        message = Unpooled.buffer(bs.length);
        message.writeBytes(bs);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
            throws Exception {
        cause.printStackTrace();
        // 异常时,调用这个方法
        ctx.close();
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        //  当客户端和服务器 TCP 链路建立成功之后,调用这个方法.
        ctx.writeAndFlush(message);
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg)
            throws Exception {
        // 当服务端返回应答消息时,调用这个方法.
        ByteBuf buf = (ByteBuf) msg;
        byte[] bs = new byte[buf.readableBytes()];
        buf.readBytes(bs);
        System.out.println(new String(bs, "utf-8"));
    }

}