java网络通信：netty

Netty提供异步的、事件驱动的网络应用程序框架和工具，用以快速开发高性能、高可靠性的网络服务器和客户端程序。

也就是说，Netty 是一个基于NIO的客户，服务器端编程框架，使用Netty 可以确保你快速和简单的开发出一个网络应用，例如实现了某种协议的客户，服务端应用。Netty相当简化和流线化了网络应用的编程开发过程，例如，TCP和UDP的socket服务开发。

本文示例采用netty 5.0。上代码.

服务端:

import io.netty.bootstrap.ServerBootstrap;

import io.netty.channel.ChannelFuture;

import io.netty.channel.ChannelOption;

import io.netty.channel.EventLoopGroup;

import io.netty.channel.nio.NioEventLoopGroup;

import io.netty.channel.socket.nio.NioServerSocketChannel;

public class TimeServer {

    public void bind(int port) throws Exception {

        // 配置服务端的NIO，循环事件线程组

        EventLoopGroup bossGroup = new NioEventLoopGroup();

        EventLoopGroup workerGroup = new NioEventLoopGroup();

        try {

            ServerBootstrap b = new ServerBootstrap();//配置类

            //NioServerSocketChannel作为channel类，它的功能对应于JDK NIO类库中的ServerSocketChannel

            b.group(bossGroup, workerGroup)

                    .channel(NioServerSocketChannel.class)

                    .option(ChannelOption.SO_BACKLOG, 1024)

                    .childHandler(new TimeServerHandler());//绑定事件处理类

            // 绑定端口，同步等待成功

            ChannelFuture f = b.bind(port).sync();

            // 等待服务端监听端口关闭

            f.channel().closeFuture().sync();

        } finally {

            // 优雅退出，释放线程池资源

            bossGroup.shutdownGracefully();

            workerGroup.shutdownGracefully();

        }

    }

    public static void main(String[] args) throws Exception {

        int port = 8080;

        if (args != null && args.length > 0) {

            try {

                port = Integer.valueOf(args[0]);

            } catch (NumberFormatException e) {

                // 采用默认值

            }

        }

        new TimeServer().bind(port);

    }

}

服务端事务处理类:

import io.netty.buffer.ByteBuf;

import io.netty.buffer.Unpooled;

import io.netty.channel.ChannelHandlerAdapter;

import io.netty.channel.ChannelHandlerContext;

public class TimeServerHandler extends ChannelHandlerAdapter {

　　/*当有数据时，自动调用，读取msg*/

    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 TIME ORDER".equalsIgnoreCase(body) ? new java.util.Date(

                System.currentTimeMillis()).toString() : "BAD ORDER";

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

        ctx.write(resp);

    }

    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {

        ctx.flush();

    }

    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {

    ctx.close();

    }

}

客户端：

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;

public class TimeClient {

    public void connect(int port, String host) throws Exception {

        // 配置客户端NIO线程组

        EventLoopGroup group = new NioEventLoopGroup();

        try {

            Bootstrap b = new Bootstrap();

            b.group(group).channel(NioSocketChannel.class)

                    .option(ChannelOption.TCP_NODELAY, true)

                    .handler(new ChannelInitializer<SocketChannel>() {
//ChannelInitializer<SocketChannel>匿名类初始化channel的pipeline，将客户端事务处理类加入到队列中

                        @Override

                        public void initChannel(SocketChannel ch)

                                throws Exception {

                            ch.pipeline().addLast(new TimeClientHandler());

                        }

                    });

            // 发起异步连接操作

            ChannelFuture f = b.connect(host, port).sync();

            // 当代客户端链路关闭

            f.channel().closeFuture().sync();

        } finally {

            // 优雅退出，释放NIO线程组

            group.shutdownGracefully();

        }

    }

    public static void main(String[] args) throws Exception {

    int port = 8080;

    if (args != null && args.length > 0) {

        try {

        port = Integer.valueOf(args[0]);

        } catch (NumberFormatException e) {

        // 采用默认值

        }

    }

    new TimeClient().connect(port, "127.0.0.1");

    }

}

客户端事件处理类：

import io.netty.buffer.ByteBuf;

import io.netty.buffer.Unpooled;

import io.netty.channel.ChannelHandlerAdapter;

import io.netty.channel.ChannelHandlerContext;

import java.util.logging.Logger;

public class TimeClientHandler extends ChannelHandlerAdapter {

    private static final Logger logger = Logger

        .getLogger(TimeClientHandler.class.getName());

    private final ByteBuf firstMessage;

    public TimeClientHandler() {

        byte[] req = "QUERY TIME ORDER".getBytes();

        firstMessage = Unpooled.buffer(req.length);

        firstMessage.writeBytes(req);

    }

　　/*连接成功后，自动发送消息*/

    public void channelActive(ChannelHandlerContext ctx) {

    　　ctx.writeAndFlush(firstMessage);

    }

　　/*有消息返回时，自动调用该函数读取*/

    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("Now is : " + body);

    }

　　/*发生异常时，自动调用*/

    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {

        // 释放资源

        logger.warning("Unexpected exception from downstream : "

            + cause.getMessage());

        ctx.close();

    }

}

巴特西

java网络通信：netty

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