基于java序列化的Netty编解码技术

    基于Java提供的对象输入/输出流ObjectInputStream和ObjectOutputStream，可以直接把Java对象作为可存储的字节数组写入文件，也可以传输到网络上。对程序员来说，基于JDK默认的序列号机制可以避免操作底层的字节数组，从而提高开发效率。

    相信大多数Java程序员接触到的第一种序列化或者编解码技术就是Java默认序列化，只需要序列化的POJO对象实现java.io.Serializable接口，根据实际情况生成序列ID，这个类就能通过java.io.ObjectInput和java.io.ObjectOutput序列化和反序列化。

1、服务端开发

    （1）在服务端ChannelPipeline中添加ObjectDecoder解码器。

    （2）在服务端ChannelPipeline中添加ObjectEncoder编码器。

    （3）需要序列化的POJO类实现Serializable接口。

    （4）构造服务端处理类，处理客户端请求。

 

    请求POJO类

 

package com.serial.java.pojo;

import java.io.Serializable;

/**
 * 
 * @author leeka
 * @notice 
 *	1、实现Serializable接口
 *  2、生成默认的序列化ID
 *  3、重写toString()方法，方便输出
 */
public class SubscribeReq implements Serializable {

	private static final long serialVersionUID = 1L;
	
	private int subReqID;
	private String userName;
	private String productName;
	private String phoneNumber;
	private String address;
	public int getSubReqID() {
		return subReqID;
	}
	public void setSubReqID(int subReqID) {
		this.subReqID = subReqID;
	}
	public String getUserName() {
		return userName;
	}
	public void setUserName(String userName) {
		this.userName = userName;
	}
	public String getProductName() {
		return productName;
	}
	public void setProductName(String productName) {
		this.productName = productName;
	}
	public String getPhoneNumber() {
		return phoneNumber;
	}
	public void setPhoneNumber(String phoneNumber) {
		this.phoneNumber = phoneNumber;
	}
	public String getAddress() {
		return address;
	}
	public void setAddress(String address) {
		this.address = address;
	}
	@Override
	public String toString() {
		return "SubscribeReq [subReqID=" + subReqID + ", userName=" + userName + ", productName=" + productName
				+ ", phoneNumber=" + phoneNumber + ", address=" + address + "]";
	}
}

 

    响应POJO类

 

package com.serial.java.pojo;

import java.io.Serializable;
/**
 * 
 * @author leeka
 * @notice 
 *	1、实现Serializable接口
 *  2、生成默认的序列化ID
 *  3、重写toString()方法，方便输出
 */
public class SubscribeResp  implements Serializable{

	private static final long serialVersionUID = 1L;
	private int subReqID;
	private int respCode;
	private String desc;
	public int getSubReqID() {
		return subReqID;
	}
	public void setSubReqID(int subReqID) {
		this.subReqID = subReqID;
	}
	public int getRespCode() {
		return respCode;
	}
	public void setRespCode(int respCode) {
		this.respCode = respCode;
	}
	public String getDesc() {
		return desc;
	}
	public void setDesc(String desc) {
		this.desc = desc;
	}
	
	@Override
	public String toString() {
		return "SubscribeResp [subReqID=" + subReqID + ", respCode=" + respCode + ", desc=" + desc + "]";
	}
	
}

 

 

    服务端入口

package com.serial.java;

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;
import io.netty.handler.codec.serialization.ClassResolvers;
import io.netty.handler.codec.serialization.ObjectDecoder;
import io.netty.handler.codec.serialization.ObjectEncoder;


public class SubReqServer {

	public void bind(int port)throws Exception{
		
		//配置服务端NIO线程组
		EventLoopGroup bossGroup = new NioEventLoopGroup();
		EventLoopGroup workerGroup = new NioEventLoopGroup();
		try{
			ServerBootstrap b = new ServerBootstrap();
			b.group(bossGroup, workerGroup)
				.channel(NioServerSocketChannel.class)
				.option(ChannelOption.SO_BACKLOG, 1024)
				.childHandler(new ChannelInitializer<SocketChannel>() {

					@Override
					protected void initChannel(SocketChannel ch) throws Exception {
						ch.pipeline()
						.addLast(new ObjectDecoder(1024*1024//为防止异常码流和解码错位导致的内存溢出，将对象序列化后的最大字节数组长度设为1M
								, ClassResolvers.weakCachingConcurrentResolver(//创建线程安全的WeakReferenceMap对类加载器进行缓存
										this.getClass().getClassLoader())))						
						.addLast(new ObjectEncoder())//对实现了Serializable的POJO对象进行编码
						.addLast(new SubReqServerHandler());						
					}
					
				});
			//绑定端口，同步等待成功
			ChannelFuture f = b.bind(port).sync();
			//等待服务端监听端口关闭
			f.channel().closeFuture().sync();
			
		}finally{
			//退出时释放资源
			bossGroup.shutdownGracefully();
			workerGroup.shutdownGracefully();
		}		
	}
	
	public static void main(String[] args) throws Exception{
		int port = 8084;
		if(args!=null && args.length > 0){
			port = Integer.valueOf(args[0]);
		}
		new SubReqServer().bind(port);		
	}
}

 

    自定义服务端处理类

package com.serial.java;

import com.serial.java.pojo.SubscribeReq;
import com.serial.java.pojo.SubscribeResp;

import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;

public class SubReqServerHandler extends ChannelHandlerAdapter {

	@Override
	public void channelRead(ChannelHandlerContext ctx, Object msg)
			throws Exception {
		SubscribeReq req = (SubscribeReq) msg;
		if("leeka".equalsIgnoreCase(req.getUserName())){
			System.out.println("service accept client subscribe req:["+ req +"]");
			ctx.writeAndFlush(resp(req.getSubReqID()));		
		}
	}
	
	private SubscribeResp resp(int subReqID){
		SubscribeResp resp = new SubscribeResp();
		resp.setSubReqID(subReqID);
		resp.setRespCode(0);
		resp.setDesc("Netty book order succeed, 3 days later, sent to the designated address");
		return resp;
	}
	
//	@Override
//	public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
//		ctx.flush();
//	}
	
	@Override
	public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
			throws Exception {
		//super.exceptionCaught(ctx, cause);
		ctx.close();
	}
	
}

 

2、客户端开发

    （1）将Netty对象编码器和解码器添加到ChannelPipeline。

    （2）客户端一次构造十个请求，最后一次性发送给服务端。

    （3）自定义客户端处理类打印服务端响应的消息。

 

    客户端入口

package com.serial.java;

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;
import io.netty.handler.codec.serialization.ClassResolvers;
import io.netty.handler.codec.serialization.ObjectDecoder;
import io.netty.handler.codec.serialization.ObjectEncoder;

public class SubReqClient {
	
	public void connect(int port,String host)throws Exception{
		
		//配置客户端NIO线程组
		EventLoopGroup group = new NioEventLoopGroup();
		
		try{
			Bootstrap b = new Bootstrap();
			b.group(group).channel(NioSocketChannel.class)
				.option(ChannelOption.TCP_NODELAY, true)
				.handler(new ChannelInitializer<SocketChannel>() {
					@Override
					protected void initChannel(SocketChannel ch) throws Exception {
						ch.pipeline()
						.addLast(new ObjectDecoder(1024
								, ClassResolvers.cacheDisabled(//禁止对类加载器进行缓存
										this.getClass().getClassLoader())))						
						.addLast(new ObjectEncoder())//对实现了Serializable的POJO对象进行编码
						.addLast(new SubReqClientHandler());				
					};
				});
			
			//发起异步连接操作
			ChannelFuture f = b.connect(host,port).sync();
			//等待客户端链路关闭
			f.channel().closeFuture().sync();
		}finally{
			//退出，释放资源
			group.shutdownGracefully();
		}
		
	}
	
	public static void main(String[] args)throws Exception {
		int port = 8084;
		if(args!=null && args.length > 0){
			port = Integer.valueOf(args[0]);
		}
		new SubReqClient().connect(port, "127.0.0.1");		
	}
}

 

    客户端处理类

package com.serial.java;

import java.util.logging.Logger;

import com.serial.java.pojo.SubscribeReq;

import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;

public class SubReqClientHandler extends ChannelHandlerAdapter {

	private static final Logger logger = Logger.getLogger(SubReqClientHandler.class.getName());
	
	public SubReqClientHandler() {	
	}
	
	@Override
	public void channelActive(ChannelHandlerContext ctx) throws Exception {
		for (int i = 0; i < 10; i++) {
			ctx.write(req(i));
		}
		ctx.flush();
	}
	
	private SubscribeReq req(int i){
		SubscribeReq r = new SubscribeReq();
		r.setSubReqID(i);
		r.setAddress("浙江省杭州市西湖区");
		r.setPhoneNumber("1516844444"+i);
		r.setProductName("Netty权威指南系列"+i);
		r.setUserName("leeka");
		return r;
	}
	
	@Override
	public void channelRead(ChannelHandlerContext ctx, Object msg)
			throws Exception {
		System.out.println("receive server response:["+msg+"]");
	}
	
	@Override
	public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
			throws Exception {
		logger.warning("unexpected exception from downstream:"+ cause.getMessage());
		ctx.close();
	}
	
}

   

    Java序列化虽然很方便，但也有它的缺点： （1）无法跨语言；（2）序列化后码流大；（3）序列化性能低。目前业界主流的编解码框架有Google的Protobuf、Facebook的Thrift、Jboss的Marshalling等，大家不妨结合这些主流的编解码框架进行编解码操作。

 

OVER

评论

1 楼 quanwsx 2016-09-17