Netty 4 传输对象

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2024-07-07 00:55:23 230人阅读

　　对于Netty在这里就不做过多介绍了，详情咨询http://netty.io/wiki/user-guide-for-4.x.html

　　我们在使用netty的过程中肯定会遇到传输对象的情况，Netty4通过ObjectEncoder和ObjectDecoder来支持。

　　首先我们定义一个User对象，一定要实现Serializable接口：

import java.io.Serializable;

/**
 * User: hupeng
 * Date: 14-6-3
 * Time: 上午1:31
 */
public class User implements Serializable {


    private int id;

    private String name;

    private String cardNo;

    private String description;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getCardNo() {
        return cardNo;
    }

    public void setCardNo(String cardNo) {
        this.cardNo = cardNo;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }


    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name=‘" + name + ‘\‘‘ +
                ", cardNo=‘" + cardNo + ‘\‘‘ +
                ", description=‘" + description + ‘\‘‘ +
                ‘}‘;
    }
}

然后定义一个客户端：

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

public class ObjectTransferClient {
    private String host;

    private int port;

    private int messageSize;


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

    public void run() throws InterruptedException {
        Bootstrap bootstrap = new Bootstrap();
        EventLoopGroup eventLoopGroup = new NioEventLoopGroup();

        try {
            bootstrap.group(eventLoopGroup)
                    .channel(NioSocketChannel.class)
                    .handler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            ch.pipeline().addLast(
                                    new ObjectEncoder(),
                                    new ObjectDecoder(Integer.MAX_VALUE ,ClassResolvers.cacheDisabled(null)),
                                    new ObjectTransferClientHandler(messageSize));
                        }
                    });

            ChannelFuture future = bootstrap.connect(host, port).sync();

            future.channel().closeFuture().sync();
        } finally {
            eventLoopGroup.shutdownGracefully();
        }
    }


    public static void main(String[] args) throws Exception {
        final String host = "127.0.0.1";
        final int port = 8080;
        final int messageSize = 200;

        new ObjectTransferClient(host, port, messageSize).run();
    }
}

以及客户端的一个handler

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

import java.util.ArrayList;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;

public class ObjectTransferClientHandler extends ChannelInboundHandlerAdapter {

    private static final Logger logger = Logger.getLogger(
            ObjectTransferClientHandler.class.getName());

    private final List<User> message;

    /**
     * Creates a client-side handler.
     */
    public ObjectTransferClientHandler(int messageSize) {
        if (messageSize <= 0) {
            throw new IllegalArgumentException(
                    "firstMessageSize: " + messageSize);
        }
        message = new ArrayList<User>(messageSize);
        for (int i = 0; i < messageSize; i ++) {
            User user = new User();
            user.setId(i);
            user.setCardNo("420000" + i);
            user.setName("hu" +i);
            user.setDescription("你觉得这样好吗？？真的好吗" + i);
            message.add(user);
        }
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        // Send the message to Server
        ctx.writeAndFlush(message);
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        // you can use the Object from Server here
        System.out.println(msg);
        ctx.close();
    }


    @Override
    public void exceptionCaught(
            ChannelHandlerContext ctx, Throwable cause) throws Exception {
        logger.log(
                Level.WARNING,
                "Unexpected exception from downstream.", cause);
        ctx.close();
    }
}

然后是服务端：

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

public class ObjectTranferServer {

    private final int port;

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

    public void run() throws Exception {
        EventLoopGroup bossGroup = new NioEventLoopGroup(1);
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        public void initChannel(SocketChannel ch) throws Exception {
                            ch.pipeline().addLast(
                                    new ObjectEncoder(),
                                    new ObjectDecoder(Integer.MAX_VALUE,ClassResolvers.cacheDisabled(null)),
                                    new ObjectTransferServerHandler());
                        }
                    });

            // Bind and start to accept incoming connections.
            b.bind(port).sync().channel().closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }

    public static void main(String[] args) throws Exception {
        int port;
        if (args.length > 0) {
            port = Integer.parseInt(args[0]);
        } else {
            port = 8080;
        }
        new ObjectTranferServer(port).run();
    }
}

服务端Handler：

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

import java.util.logging.Level;
import java.util.logging.Logger;

public class ObjectTransferServerHandler extends ChannelInboundHandlerAdapter {

    private static final Logger logger = Logger.getLogger(
            ObjectTransferServerHandler.class.getName());


    @Override
    public void channelRead(
            ChannelHandlerContext ctx, Object msg) throws Exception {
        System.out.println(msg);
        ctx.write(msg);
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
        ctx.flush();
        ctx.close();
    }

    @Override
    public void exceptionCaught(
            ChannelHandlerContext ctx, Throwable cause) throws Exception {
        logger.log(
                Level.WARNING,
                "Unexpected exception from downstream.", cause);
        ctx.close();
    }
}

这里我传入的size为200的一个list对象。当我把size增加到1000的时候，客户端和服务端都不报任何错误，但是也接收不到值。。具体原因还在寻找中，如果亲爱的你，可以指点一下我，那简直就是太好了。。。。

当然我们也可以采取其他方式，比如在客户端和服务端，通过json来序列化和反序列化传递，然后按照String来处理就行了

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Netty 4 传输对象

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