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 @Overrideprotected void initChannel(SocketChannel ch)throws Exception {// 注册编码的handlerch.pipeline().addLast(new PersonEncoder()); //out//注册处理消息的handlerch.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 @Overridepublic 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 @Overrideprotected 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 @Overridepublic 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 @Overrideprotected 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 @Overrideprotected void initChannel(Channel ch) throws Exception {//注册解码的handlerch.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 {@Overridepublic 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);}@Overridepublic 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 }@Overridepublic 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 {@Overrideprotected 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objectObject 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;}}}

 

转载于:https://www.cnblogs.com/yaowen/p/9031819.html

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