Netty4.x中文教程系列(四)  对象传输 

package mjorcen.netty.object;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 + ‘\‘‘ + ‘}‘;    }}

package mjorcen.netty.object;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 = 11000;        }        new ObjectTranferServer(port).run();    }}

package mjorcen.netty.object;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.writeAndFlush(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();    }}

package mjorcen.netty.object;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 = "localhost";        final int port = 11000;        final int messageSize = 20;        new ObjectTransferClient(host, port, messageSize).run();    }}

package mjorcen.netty.object;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        super.channelActive(ctx);        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();    }}

1. 通过Netty传递，都需要基于流，以ChannelBuffer的形式传递。所以，Object -> ChannelBuffer.
2. Netty提供了转换工具，需要我们配置到Handler。
3. 样例从客户端 -> 服务端，单向发消息，所以在客户端配置了编码，服务端解码。如果双向收发，则需要全部配置Encoder和Decoder。

　　这里需要注意，注册到Server的Handler是有顺序的，如果你颠倒一下注册顺序：