Question

为什么客户端没有收到服务器发送的POJO？

这blog sample对我来说有点困难。

我意识到这是很多代码，但我不知道如何在客户端和服务器之间使用POJO（在这种情况下为Quote）时减少这种情况。建立连接时，服务器发送报价：

run:
     [java] Aug 03, 2014 5:32:20 PM net.bounceme.dur.netty.QuoteServerInitializer <init>
     [java] INFO: ..initializing..
     [java] Aug 03, 2014 5:32:23 PM net.bounceme.dur.netty.QuoteServerInitializer initChannel
     [java] INFO: ..adding to pipeline..
     [java] Aug 03, 2014 5:32:23 PM net.bounceme.dur.netty.QuoteServerHandler <init>
     [java] INFO: ..started..
     [java] Aug 03, 2014 5:32:23 PM net.bounceme.dur.netty.QuoteServerHandler channelActive
     [java] INFO: ..sending new server Quote..
     [java] Aug 03, 2014 5:32:23 PM net.bounceme.dur.netty.QuoteEncoder encode
     [java] INFO: 
     [java] 
     [java] id      0
     [java] quote   Where there is love there is life.
^Cthufir@dur:~/NetBeansProjects/QuoteServer$ 
thufir@dur:~/NetBeansProjects/QuoteServer$ ^C
thufir@dur:~/NetBeansProjects/QuoteServer$

但它似乎永远不会到达客户端：

run:
     [java] Aug 03, 2014 5:32:23 PM net.bounceme.dur.netty.QuoteClientInitializer <init>
     [java] INFO: ..initializing..
     [java] Aug 03, 2014 5:32:23 PM net.bounceme.dur.netty.QuoteClientHandler channelActive
     [java] INFO: ..sending new client Quote..
     [java] Aug 03, 2014 5:32:23 PM net.bounceme.dur.netty.QuoteEncoder encode
     [java] INFO: 
     [java] 
     [java] id      0
     [java] quote   client
^Cthufir@dur:~/NetBeansProjects/QuoteClient$ 
thufir@dur:~/NetBeansProjects/QuoteClient$

同样，客户端发送的引用似乎永远不会出现在服务器上。为什么呢？

服务器：

package net.bounceme.dur.netty;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import java.util.logging.Logger;

public final class QuoteServer {

    private static final Logger log = Logger.getLogger(QuoteServer.class.getName());

    public static void main(String... args) throws InterruptedException {
        MyProps p = new MyProps();
        int port = p.getServerPort();
        new QuoteServer().pingPong(port);
    }

    private void pingPong(int port) throws InterruptedException {
        EventLoopGroup bossGroup = new NioEventLoopGroup(1);
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .handler(new LoggingHandler(LogLevel.DEBUG))
                    .childHandler(new QuoteServerInitializer());
            b.bind(port).sync().channel().closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

服务器初始化程序： package net.bounceme.dur.netty;

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.Delimiters;
import java.util.logging.Logger;

public class QuoteServerInitializer extends ChannelInitializer<SocketChannel> {

    private static final Logger log = Logger.getLogger(QuoteServerInitializer.class.getName());

    public QuoteServerInitializer() {
        log.info("..initializing..");
    }

    @Override
    public void initChannel(SocketChannel ch) throws Exception {
        log.info("..adding to pipeline..");
        ChannelPipeline pipeline = ch.pipeline();
        pipeline.addLast(new DelimiterBasedFrameDecoder(8192, Delimiters.lineDelimiter()));
        pipeline.addLast(new QuoteDecoder());
        pipeline.addLast(new QuoteEncoder());
        pipeline.addLast(new QuoteServerHandler());
    }
}

服务器处理程序：
package net.bounceme.dur.netty;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import java.util.Random;
import java.util.logging.Logger;
import net.bounceme.dur.jdbc.Quote;

public class QuoteServerHandler extends SimpleChannelInboundHandler<Quote> {

    private static final Logger log = Logger.getLogger(QuoteServerHandler.class.getName());
    private static final Random random = new Random();

    public QuoteServerHandler() {
        log.info("..started..");
    }

    // Quotes from Mohandas K. Gandhi:
    private static final String[] quotes = {
        "Where there is love there is life.",
        "First they ignore you, then they laugh at you, then they fight you, then you win.",
        "Be the change you want to see in the world.",
        "The weak can never forgive. Forgiveness is the attribute of the strong.",};

    private static Quote nextQuote() {
        int quoteId;
        synchronized (random) {
            quoteId = random.nextInt(quotes.length);
        }
        return new Quote(quotes[quoteId]);
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        log.info("..sending new server Quote..");
        ctx.writeAndFlush(nextQuote());
    }

    @Override
    protected void channelRead0(ChannelHandlerContext chc, Quote quote) throws Exception {
        log.info(quote.toString());
        chc.writeAndFlush(nextQuote());
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        log.info(msg.toString());
        ctx.writeAndFlush(nextQuote());
    }

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

}

客户端： package net.bounceme.dur.netty;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;
import java.io.IOException;
import java.util.logging.Logger;

public final class QuoteClient {

    private static final Logger log = Logger.getLogger(QuoteClient.class.getName());

    public static void main(String... args) throws InterruptedException, IOException {
        new QuoteClient().connect();
    }

    public void connect() throws InterruptedException, IOException {
        MyProps p = new MyProps();
        String host = p.getHost();
        int port = p.getServerPort();
        pingPong(host, port);
    }

    public void pingPong(String host, int port) throws InterruptedException, IOException {
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            Bootstrap b = new Bootstrap();
            b.group(group)
                    .channel(NioSocketChannel.class)
                    .handler(new QuoteClientInitializer());
            ChannelFuture cf = b.connect(host, port);
            cf.sync().channel().closeFuture().sync();
        } finally {
            group.shutdownGracefully();
        }
    }
}

客户端初始化程序： package net.bounceme.dur.netty;

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.Delimiters;
import java.util.logging.Logger;

public class QuoteClientInitializer extends ChannelInitializer<SocketChannel> {

    private static final Logger log = Logger.getLogger(QuoteClientInitializer.class.getName());

    public QuoteClientInitializer() {
        log.info("..initializing..");
    }

    @Override
    public void initChannel(SocketChannel ch) {
        ChannelPipeline pipeline = ch.pipeline();
        pipeline.addLast(new DelimiterBasedFrameDecoder(8192, Delimiters.lineDelimiter()));
        pipeline.addLast(new QuoteDecoder());
        pipeline.addLast(new QuoteEncoder());
        pipeline.addLast(new QuoteClientHandler());
    }
}

客户端处理程序： package net.bounceme.dur.netty;

import io.netty.channel.ChannelHandler.Sharable;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import java.util.logging.Logger;
import net.bounceme.dur.jdbc.Quote;

@Sharable
public class QuoteClientHandler extends SimpleChannelInboundHandler<Quote> {

    private static final Logger log = Logger.getLogger(QuoteClient.class.getName());

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        log.info("..sending new client Quote..");
        ctx.writeAndFlush(new Quote("client"));
    }

    @Override
    protected void channelRead0(ChannelHandlerContext chc, Quote quote) throws Exception {
        log.info(quote.toString());
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        log.info(msg.toString());
        ctx.writeAndFlush(new Quote("client"));
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) {
        ctx.fireChannelReadComplete();
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        log.info(cause.toString());
        ctx.close();
    }

}

解码器： package net.bounceme.dur.netty;

import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToMessageDecoder;
import java.util.List;
import java.util.logging.Logger;
import net.bounceme.dur.jdbc.Quote;

public class QuoteDecoder extends MessageToMessageDecoder<Quote> {

    private static final Logger log = Logger.getLogger(QuoteDecoder.class.getName());

    @Override
    protected void decode(ChannelHandlerContext chc, Quote quote, List<Object> list) throws Exception {
        log.info(quote.toString());
        list.add(quote);
    }
}

编码器： package net.bounceme.dur.netty;

import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToMessageEncoder;
import java.util.List;
import java.util.logging.Logger;
import net.bounceme.dur.jdbc.Quote;

public class QuoteEncoder extends MessageToMessageEncoder<Quote> {

            private static final Logger log = Logger.getLogger(QuoteEncoder.class.getName());


    @Override
    protected void encode(ChannelHandlerContext chc, Quote quote, List<Object> list) throws Exception {
        log.info(quote.toString());
        list.add(quote);
    }
}

值得注意的是，en / de-code方法永远不会登录到控制台。

Answer 1

如果您将QuoteServerHandler的channelActive方法编辑为以下内容：

@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
    log.info("..sending new server Quote..");
    ChannelFuture cf = ctx.writeAndFlush(nextQuote());
    if (!cf.isSuccess()){
        log.log(Level.SEVERE, cf.toString());
    }
    ctx.fireChannelActive();
}

那么你很可能会收到一条消息：unsupported message type: Quote

您的编码器需要将其编码为支持的内容。我现在不会这样做。

我建议使用可以将ObjectEncoder编码为Quote的{{1}}。

在接收网站上，您需要ByteBuf。之后，您可以将收到的msg在ClientHandler中转发回ObjectDecoder。

带有POJO的Netty乒乓球

1 个答案: