Netty初探-netty服务端和客户端demo

通过netty框架实现一个简单的服务端和客户端框架，相比于前面所说的NIO，netty的api使用更加简单灵活，扩展性强。

• TimeServer

package com.xpn.netty.netty;

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;

public class TimeServer {

    public void bind(int port) throws InterruptedException {
        // 配置NIO线程组
        EventLoopGroup bossGroup = new NioEventLoopGroup();// 连接线程
        EventLoopGroup workerGroup = new NioEventLoopGroup();// 处理线程组
        try {
            ServerBootstrap bootstrap = new ServerBootstrap();
            bootstrap.group(bossGroup, workerGroup);
            bootstrap.channel(NioServerSocketChannel.class);
            bootstrap.option(ChannelOption.SO_BACKLOG, 1024);
            bootstrap.childHandler(new ChildChannelHandler());
            // 绑定端口，同步等待成功
            ChannelFuture future = bootstrap.bind(port).sync();
            // 等待服务端监听端口关闭，等待服务端链路关闭之后main函数才退出
            future.channel().closeFuture().sync();
        } finally {
            // 优雅退出，释放线程池资源
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }

    }

    private class ChildChannelHandler extends ChannelInitializer<SocketChannel> {

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

        }

    }

    public static void main(String[] args) throws InterruptedException {
        int port = 8080;
        if (args != null && args.length > 0) {
            port = Integer.parseInt(args[0]);
        }
        new TimeServer().bind(port);

    }

}

• TimeClient

package com.xpn.netty.netty;

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 {

/**
 * @param args
 */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        String host = "localhost";
        int port = 8080;
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            Bootstrap bootstrap = new Bootstrap();
            bootstrap.group(workerGroup);
            bootstrap.channel(NioSocketChannel.class);
            bootstrap.option(ChannelOption.SO_KEEPALIVE, true);
            bootstrap.handler(new ChannelInitializer<SocketChannel>() {

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

                }
            });
            // 发起异步连接操作
            ChannelFuture future = bootstrap.connect(host, port).sync();

            future.channel().closeFuture().sync();
        } catch (Exception e) {
            workerGroup.shutdownGracefully();
        }
    }

}

• TimeServerHandler

package com.xpn.netty.netty;

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

import java.util.Date;

public class TimeServerHandler extends ChannelHandlerAdapter {

@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
throws Exception {
// TODO Auto-generated method stub
        cause.printStackTrace();
        ctx.close();
    }

@Override
public void channelRead(ChannelHandlerContext ctx, Object msg)
throws Exception {
        ByteBuf buf = (ByteBuf) msg;
byte[] req = new byte[buf.readableBytes()];// 获得缓冲区可读的字节数
        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 Date(
                System.currentTimeMillis()).toString() : "bad order";
        ByteBuf resp = Unpooled.copiedBuffer(currentTime.getBytes());
        ctx.write(resp);// 性能考虑，仅将待发送的消息发送到缓冲数组中，再通过调用flush方法，写入channel中
    }

@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
        ctx.flush();// 将消息发送队列中的消息写入到SocketChannel中发送给对方。
    }

}

• TimeClientHandler

package com.xpn.netty.netty;

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);
    }

@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
        ctx.writeAndFlush(firstMessage);// 将请求消息发送给服务端
    }

@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
throws Exception {
        LOGGER.warning("Unexpected exception from downstrema : "
                + cause.getMessage());
        ctx.close();
    }

@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("Now is : " + body);

    }

}