Netty学习笔记 （实验篇）三

这次实现一个TimeServer和一个TimeClient 主要功能就是 Client连接到Server后 Server立即返回一个32位的时间整数，然后断开连接，客户端在接收到时间后，转换成可读格式  输出。

TimeServer 代码如下：

package netty.learn.time1;

import io.netty.bootstrap.ServerBootstrap;
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.NioServerSocketChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;

/**
 * What's the Class to do
 * User: mzy
 * Date: 13-6-20
 * Time: 下午8:46
 * Version:${VERSION}
 */
public class TimeServer {

    private int port;

    public void run(){
        ServerBootstrap b = new ServerBootstrap();
        EventLoopGroup boss = new NioEventLoopGroup();
        EventLoopGroup worker = new NioEventLoopGroup();
        b.group(boss,worker).channel(NioServerSocketChannel.class)
                .childHandler(new ChannelInitializer<SocketChannel>() {
                    @Override
                    protected void initChannel(SocketChannel socketChannel) throws Exception {
                        socketChannel.pipeline().addLast(new LoggingHandler(LogLevel.INFO),new TimeServerHandler());
                    }
                });
        try{
            b.bind(port).sync().channel().closeFuture().sync();
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            boss.shutdownGracefully();
            worker.shutdownGracefully();
        }

    }

    public TimeServer(int port) {
        this.port = port;
    }

    public static void main(String[] args) {
        new TimeServer(8080).run();
    }
}

TimeServerHandler代码如下：

package netty.learn.time1;

import io.netty.buffer.ByteBuf;
import io.netty.channel.*;

/**
 * What's the Class to do
 * User: mzy
 * Date: 13-6-20
 * Time: 下午8:48
 * Version:${VERSION}
 */
public class TimeServerHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        final ByteBuf time = ctx.alloc().buffer(4);
        time.writeInt((int)(System.currentTimeMillis()/1000L+2208988800L));
        final ChannelFuture future = ctx.write(time);
        future.addListener(ChannelFutureListener.CLOSE);
    }

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

当我们运行服务器端后可以用nc测试一下：

从nc的返回数据来看是四个字符，应该是在终端把32位的整数转换为了 4个8位的字符

这样的格式显然不可读，所以我们写一个Client用来转换数据

Client代码如下：

package netty.learn.time1;

import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;

import java.util.Date;

/**
 * What's the Class to do
 * User: mzy
 * Date: 13-6-23
 * Time: 下午2:34
 * Version:${VERSION}
 */
class TimeClientHandler extends ChannelInboundHandlerAdapter{
    @Override
    public void messageReceived(ChannelHandlerContext ctx, MessageList<Object> msgs) throws Exception {
        ByteBuf time = (ByteBuf) msgs.cast().get(0);
        long currentTimeMillis = (time.readInt()-2208988800L)*1000L;
        System.out.print(new Date(currentTimeMillis));
        msgs.releaseAllAndRecycle();
        ctx.close();
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}
public class TimeClient  {

    private String host;
    private int port;

    public TimeClient(String host, int port) {
        this.host = host;
        this.port = port;
    }

    public void run(){
        EventLoopGroup group = new NioEventLoopGroup();
        Bootstrap b = new Bootstrap();
        b.group(group).channel(NioSocketChannel.class)
                .option(ChannelOption.SO_KEEPALIVE,true)
                .handler(new ChannelInitializer<SocketChannel>() {
                    @Override
                    protected void initChannel(SocketChannel socketChannel) throws Exception {
                        socketChannel.pipeline().addLast(new TimeClientHandler());
                    }
                });
        try{
        b.connect(host,port).sync().channel().closeFuture().sync();
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            group.shutdownGracefully();
        }
    }

    public static void main(String[] args) {
        new TimeClient("localhost",8080).run();
    }
}

运行结果如下：

客户端打印请求到的时间后就断开连接。

ps：最后返回的时间不怎么对。。。

转载于:https://my.oschina.net/ccdvote/blog/139988