Hadoop25---netty，单个handler

ke客户端：

package cn.itcast_03_netty.sendstring.client;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
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.NioSocketChannel;

import java.net.InetSocketAddress;

import cn.itcast_03_netty.sendobject.coder.PersonEncoder;

/**
 * • 连接服务器 • 写数据到服务器 • 等待接受服务器返回相同的数据 • 关闭连接
 *
 * @author wilson
 *
 */
public class EchoClient {

    private final String host;
    private final int port;

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

    public void start() throws Exception {
        EventLoopGroup nioEventLoopGroup = null;
        try {
            //不用创建线程池了，内部就有线程池。netty是基于nio开发的。
            // 客户端引导类，启动的。
            Bootstrap bootstrap = new Bootstrap();
            // EventLoopGroup可以理解为是一个线程池的组，这个线程池用来处理连接、接受数据、发送数据
            nioEventLoopGroup = new NioEventLoopGroup();
            bootstrap.group(nioEventLoopGroup)//多线程处理
                    .channel(NioSocketChannel.class)//指定通道类型为NioServerSocketChannel，一种异步模式，OIO阻塞模式为OioServerSocketChannel
                    .remoteAddress(new InetSocketAddress(host, port))//地址
                    //in handler是进来的，out handler是出去的，
                    .handler(new ChannelInitializer<SocketChannel>() {//业务处理类
                                @Override
                                protected void initChannel(SocketChannel ch)
                                        throws Exception {
                                    ch.pipeline().addLast(new EchoClientHandler());//注册handler
                                }
                            });
            // 链接服务器
            ChannelFuture channelFuture = bootstrap.connect().sync();
            channelFuture.channel().closeFuture().sync();
        } finally {
            nioEventLoopGroup.shutdownGracefully().sync();
        }
    }

    public static void main(String[] args) throws Exception {
        new EchoClient("localhost", 20000).start();//不是想出的start而是普通的方法
    }
}

package cn.itcast_03_netty.sendstring.client;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import cn.itcast_03_netty.sendobject.bean.Person;

public class EchoClientHandler extends SimpleChannelInboundHandler<ByteBuf> {
    // 客户端连接服务器后被调用
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("客户端连接服务器，开始发送数据……");
        byte[] req = "QUERY TIME ORDER".getBytes();//消息
        //nio的buffer
        ByteBuf firstMessage = Unpooled.buffer(req.length);//发送类
        firstMessage.writeBytes(req);//发送
        ctx.writeAndFlush(firstMessage);//flush
    }

    // • 从服务器接收到数据后调用
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, ByteBuf msg)
            throws Exception {
        System.out.println("client 读取server数据..");
        // 服务端返回消息后
        ByteBuf buf = (ByteBuf) msg;
        byte[] req = new byte[buf.readableBytes()];
        buf.readBytes(req);
        String body = new String(req, "UTF-8");
        System.out.println("服务端数据为 :" + body);
    }

    // • 发生异常时被调用
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
            throws Exception {
        System.out.println("client exceptionCaught..");
        // 释放资源
        ctx.close();
    }
}

服务端：

package cn.itcast_03_netty.sendstring.server;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import cn.itcast_03_netty.sendobject.coder.PersonDecoder;

/**
 * • 配置服务器功能，如线程、端口 • 实现服务器处理程序，它包含业务逻辑，决定当有一个请求连接或接收数据时该做什么
 *
 * @author wilson
 *
 */
public class EchoServer {

    private final int port;

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

    public void start() throws Exception {
        EventLoopGroup eventLoopGroup = null;
        try {
            //server端引导类
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            //连接池处理数据
            eventLoopGroup = new NioEventLoopGroup();
            //装配bootstrap
            serverBootstrap.group(eventLoopGroup)
            .channel(NioServerSocketChannel.class)//指定通道类型为NioServerSocketChannel，一种异步模式，OIO阻塞模式为OioServerSocketChannel
            .localAddress("localhost",port)//设置InetSocketAddress让服务器监听某个端口已等待客户端连接。
            .childHandler(new ChannelInitializer<Channel>() {//设置childHandler执行所有的连接请求
                @Override
                protected void initChannel(Channel ch) throws Exception {
                    ch.pipeline().addLast(new EchoServerHandler());//注册handler
                }
                    });
            // 最后绑定服务器等待直到绑定完成，调用sync()方法会阻塞直到服务器完成绑定,然后服务器等待通道关闭，因为使用sync()，所以关闭操作也会被阻塞。
            ChannelFuture channelFuture = serverBootstrap.bind().sync();
            System.out.println("开始监听，端口为：" + channelFuture.channel().localAddress());
            channelFuture.channel().closeFuture().sync();
        } finally {
            eventLoopGroup.shutdownGracefully().sync();
        }
    }

    public static void main(String[] args) throws Exception {
        new EchoServer(20000).start();
    }
}

package cn.itcast_03_netty.sendstring.server;

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

import java.util.Date;

import cn.itcast_03_netty.sendobject.bean.Person;

public class EchoServerHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg)
            throws Exception {
        System.out.println("server 读取数据……");
        //读取数据
        ByteBuf buf = (ByteBuf) msg;
        byte[] req = new byte[buf.readableBytes()];
        buf.readBytes(req);
        String body = new String(req, "UTF-8");
        System.out.println("接收客户端数据:" + body);
        //向客户端写数据
        System.out.println("server向client发送数据");
        String currentTime = new Date(System.currentTimeMillis()).toString();
        ByteBuf resp = Unpooled.copiedBuffer(currentTime.getBytes());
        ctx.write(resp);

    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
        System.out.println("server 读取数据完毕..");
        ctx.flush();//刷新后才将数据发出到SocketChannel
    }

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

}