hadoop28---netty传对象

Netty中，通讯的双方建立连接后，会把数据按照ByteBuf的方式进行传输，例如http协议中，就是通过HttpRequestDecoder对ByteBuf数据流进行处理，转换成http的对象。基于这个思路，我自定义一种通讯协议：Server和客户端直接传输java对象。

实现的原理是通过Encoder把java对象转换成ByteBuf流进行传输，通过Decoder把ByteBuf转换成java对象进行处理，处理逻辑如下图所示：

客户端：

package cn.itcast_03_netty.sendobject.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 {
            // 创建Bootstrap对象用来引导启动客户端
            Bootstrap bootstrap = new Bootstrap();
            // 创建EventLoopGroup对象并设置到Bootstrap中，EventLoopGroup可以理解为是一个线程池，这个线程池用来处理连接、接受数据、发送数据
            nioEventLoopGroup = new NioEventLoopGroup();
            // 创建InetSocketAddress并设置到Bootstrap中，InetSocketAddress是指定连接的服务器地址
            bootstrap.group(nioEventLoopGroup)//
                    .channel(NioSocketChannel.class)//
                    .remoteAddress(new InetSocketAddress(host, port))//
                    .handler(new ChannelInitializer<SocketChannel>() {//
                                // 添加一个ChannelHandler，客户端成功连接服务器后就会被执行
                                @Override
                                protected void initChannel(SocketChannel ch)
                                        throws Exception {
                                    // 注册编码的handler
                                    ch.pipeline().addLast(new PersonEncoder());  //out
                                    //注册处理消息的handler
                                    ch.pipeline().addLast(new EchoClientHandler());   //in
                                }
                            });
            // • 调用Bootstrap.connect()来连接服务器
            ChannelFuture f = bootstrap.connect().sync();
            // • 最后关闭EventLoopGroup来释放资源
            f.channel().closeFuture().sync();
        } finally {
            nioEventLoopGroup.shutdownGracefully().sync();
        }
    }

    public static void main(String[] args) throws Exception {
        new EchoClient("localhost", 20000).start();
    }
}

package cn.itcast_03_netty.sendobject.client;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;

import java.io.Serializable;

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("EchoClientHandler.....channelActive");
         Person person = new Person();
            person.name("angelababy");
            person.sex("girl");
            person.age(18);
            ctx.write(person);//发送对象，不用序列化，
            ctx.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();
    }
}

class Person implements Serializable {
    public static final long serialVersionUID = 1L;
    public String name;
    public String sex;
    public int age;
}

package cn.itcast_03_netty.sendobject.coder;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToByteEncoder;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;

import cn.itcast_03_netty.sendobject.bean.Person;
 /**
  * 序列化
  * 将object转换成Byte[]
  * @author wilson
  *
  */
public class PersonEncoder extends MessageToByteEncoder<Person> {//MessageToByteEncoder继承outbandler
 
    @Override
    protected void encode(ChannelHandlerContext ctx, Person msg, ByteBuf out) throws Exception {
        //工具类：将object转换为byte[]
        System.out.println("PersonEncoder--out");
        byte[] datas = objectToByte(msg);
        out.writeBytes(datas);
        ctx.flush();
    }
    
    
    /**
     * 使用IO的outputstream流将object转换为byte[]
     * @param bytes
     * @return
     */
    public byte[] objectToByte(Object obj) {
        byte[] bytes = null;
        ByteArrayOutputStream bo = new ByteArrayOutputStream();
        ObjectOutputStream oo = null;
        try {
            oo = new ObjectOutputStream(bo);
            oo.writeObject(obj);
            bytes = bo.toByteArray();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                bo.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                oo.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return bytes;
    }
}

服务端：

package cn.itcast_03_netty.sendobject.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 {
            //创建ServerBootstrap实例来引导绑定和启动服务器
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            //创建NioEventLoopGroup对象来处理事件，如接受新连接、接收数据、写数据等等
            eventLoopGroup = new NioEventLoopGroup();
            //指定通道类型为NioServerSocketChannel，一种异步模式，OIO阻塞模式为OioServerSocketChannel
            //设置InetSocketAddress让服务器监听某个端口已等待客户端连接。
            serverBootstrap.group(eventLoopGroup).channel(NioServerSocketChannel.class).localAddress("localhost",port)
            .childHandler(new ChannelInitializer<Channel>() {
                //设置childHandler执行所有的连接请求
                @Override
                protected void initChannel(Channel ch) throws Exception {
                    //注册解码的handler
                    ch.pipeline().addLast(new PersonDecoder());  //IN1  反序列化
                    //添加一个入站的handler到ChannelPipeline  
                    ch.pipeline().addLast(new EchoServerHandler());   //IN2
                }
                    });
            // 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.sendobject.server;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;

import java.io.Serializable;

import cn.itcast_03_netty.sendobject.bean.Person;

public class EchoServerHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg)
            throws Exception {
        Person person = (Person) msg;
        System.out.println(person.name);
        System.out.println(person.age);
        System.out.println(person.sex);
    }

    @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();
    }

}


class Person implements Serializable {
    public static final long serialVersionUID = 1L;
    public String name;
    public String sex;
    public int age;
}

package cn.itcast_03_netty.sendobject.coder;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.util.List;

 /**
  * 反序列化
  * 将Byte[]转换为Object
  * @author wilson
  *
  */
public class PersonDecoder extends ByteToMessageDecoder {
    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
        //工具类：将ByteBuf转换为byte[]
        ByteBufToBytes read = new ByteBufToBytes();
        byte[] bytes = read.read(in);
        //工具类：将byte[]转换为object
        Object obj = byteToObject(bytes);
        out.add(obj);
    }
    
    
    /**
     * 使用IO的inputstream流将byte[]转换为object
     * @param bytes
     * @return
     */
    public Object byteToObject(byte[] bytes) {
        Object obj = null;
        ByteArrayInputStream bi = new ByteArrayInputStream(bytes);
        ObjectInputStream oi = null;
        try {
            oi = new ObjectInputStream(bi);
            obj = oi.readObject();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                bi.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                oi.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return obj;
    }
    
    class ByteBufToBytes {
        /**
         * 将ByteBuf转换为byte[]
         * @param datas
         * @return
         */
        public byte[] read(ByteBuf datas) {
            byte[] bytes = new byte[datas.readableBytes()];// 创建byte[]
            datas.readBytes(bytes);// 将ByteBuf转换为byte[]
            return bytes;
        }
    }
 
}