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Java 服务器未实现Netty 4.x中客户端发送的消息

java netty

Java 服务器未实现Netty 4.x中客户端发送的消息,java,netty,Java,Netty,我试图通过简单地实现以下示例来学习Netty4.x。我有一个服务器和一个客户端。在某个时间点，客户机想要知道当前日期和时间，他会问服务器“现在几点了？”。当服务器意识到这个问题时，他将用当前日期和时间回答 我的实现如下 TimeClientInboundHandler.java public class TimeClientInboundHandler extends ChannelInboundHandlerAdapter { @Override public void cha

我试图通过简单地实现以下示例来学习Netty4.x。我有一个服务器和一个客户端。在某个时间点，客户机想要知道当前日期和时间，他会问服务器“现在几点了？”。当服务器意识到这个问题时，他将用当前日期和时间回答

我的实现如下

TimeClientInboundHandler.java

public class TimeClientInboundHandler extends ChannelInboundHandlerAdapter {
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        ByteBuf byteBuf = (ByteBuf) msg;
        try {
            long currentTimeMillis = (byteBuf.readUnsignedInt() - 2208988800L) * 1000L;
            System.out.println(new Date(currentTimeMillis));
            ctx.close();
        } finally {
            byteBuf.release();
        }
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        ctx.write("What time is it?");
        ctx.flush();
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}

public class TimeServerInboundHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        ByteBuf byteBuf = (ByteBuf) msg;
        try {
            byteBuf.readCharSequence(1024, StandardCharsets.UTF_8);
            System.out.println(byteBuf.toString());
        } finally {
            ((ByteBuf) msg).release();
        }
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        final ByteBuf byteBuf = ctx.alloc().buffer(4);
        byteBuf.writeInt((int) (System.currentTimeMillis() / 1000L + 2208988800L));

        final ChannelFuture f = ctx.writeAndFlush(byteBuf);
        f.addListener(new ChannelFutureListener() {
            @Override
            public void operationComplete(ChannelFuture future) throws Exception {
                assert f == future;
                ctx.close();
            }
        });
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}

public class TimeClientInboundHandler extends ChannelInboundHandlerAdapter {
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        ByteBuf byteBuf = (ByteBuf) msg;
        try {
            System.out.println("Client received: " + byteBuf.toString(StandardCharsets.UTF_8));
            ctx.close();
        } finally {
            byteBuf.release();
        }
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) {
        ctx.writeAndFlush(Unpooled.copiedBuffer("What time is it?", StandardCharsets.UTF_8));
    }

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

public class TimeServerInboundHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        ByteBuf byteBuf = (ByteBuf) msg;
        try {
            System.out.println("Server received: " + byteBuf.toString(StandardCharsets.UTF_8));
            String answer = Utils.getCurrentTime();
            ctx.writeAndFlush(Unpooled.copiedBuffer(answer, StandardCharsets.UTF_8));
        } finally {
            ((ByteBuf) msg).release();
        }
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) {
        ctx.writeAndFlush(Unpooled.EMPTY_BUFFER)
                .addListener(ChannelFutureListener.CLOSE);
    }

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

public class Utils {
    public static String getCurrentTime() {
        long currentTimeMillis = ((System.currentTimeMillis() / 1000L + 2208988800L) - 2208988800L) * 1000L;
        return new Date(currentTimeMillis).toString();
    }
}

TimeServerInboundHandler.java

public class TimeClientInboundHandler extends ChannelInboundHandlerAdapter {
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        ByteBuf byteBuf = (ByteBuf) msg;
        try {
            long currentTimeMillis = (byteBuf.readUnsignedInt() - 2208988800L) * 1000L;
            System.out.println(new Date(currentTimeMillis));
            ctx.close();
        } finally {
            byteBuf.release();
        }
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        ctx.write("What time is it?");
        ctx.flush();
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}

public class TimeServerInboundHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        ByteBuf byteBuf = (ByteBuf) msg;
        try {
            byteBuf.readCharSequence(1024, StandardCharsets.UTF_8);
            System.out.println(byteBuf.toString());
        } finally {
            ((ByteBuf) msg).release();
        }
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        final ByteBuf byteBuf = ctx.alloc().buffer(4);
        byteBuf.writeInt((int) (System.currentTimeMillis() / 1000L + 2208988800L));

        final ChannelFuture f = ctx.writeAndFlush(byteBuf);
        f.addListener(new ChannelFutureListener() {
            @Override
            public void operationComplete(ChannelFuture future) throws Exception {
                assert f == future;
                ctx.close();
            }
        });
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}

public class TimeClientInboundHandler extends ChannelInboundHandlerAdapter {
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        ByteBuf byteBuf = (ByteBuf) msg;
        try {
            System.out.println("Client received: " + byteBuf.toString(StandardCharsets.UTF_8));
            ctx.close();
        } finally {
            byteBuf.release();
        }
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) {
        ctx.writeAndFlush(Unpooled.copiedBuffer("What time is it?", StandardCharsets.UTF_8));
    }

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

public class TimeServerInboundHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        ByteBuf byteBuf = (ByteBuf) msg;
        try {
            System.out.println("Server received: " + byteBuf.toString(StandardCharsets.UTF_8));
            String answer = Utils.getCurrentTime();
            ctx.writeAndFlush(Unpooled.copiedBuffer(answer, StandardCharsets.UTF_8));
        } finally {
            ((ByteBuf) msg).release();
        }
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) {
        ctx.writeAndFlush(Unpooled.EMPTY_BUFFER)
                .addListener(ChannelFutureListener.CLOSE);
    }

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

public class Utils {
    public static String getCurrentTime() {
        long currentTimeMillis = ((System.currentTimeMillis() / 1000L + 2208988800L) - 2208988800L) * 1000L;
        return new Date(currentTimeMillis).toString();
    }
}
然而，我并没有得到预期的结果。具体来说，在服务器端，“现在几点了？”这个问题并没有在控制台上打印出来

我实施了什么错误？

原因

这个问题有两个原因

服务器端无法实现从客户端发送的消息，因为消息（从客户端）写入的方式错误。而不是
ctx.write（“现在几点了？”），我们应该实现如下
ctx.write（unmooled.coppiedBuffer（“现在几点了？”，StandardCharsets.UTF_8）；

此外，在
TimeServerInboundHandler.java
中，我们应该删除方法
channelActive（）
。这是因为当通道处于活动状态时，
channelRead（）
将永远不会触发

解决方案


TimeClientInboundHandler.java


public class TimeClientInboundHandler extends ChannelInboundHandlerAdapter {
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        ByteBuf byteBuf = (ByteBuf) msg;
        try {
            long currentTimeMillis = (byteBuf.readUnsignedInt() - 2208988800L) * 1000L;
            System.out.println(new Date(currentTimeMillis));
            ctx.close();
        } finally {
            byteBuf.release();
        }
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        ctx.write("What time is it?");
        ctx.flush();
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}



public class TimeServerInboundHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        ByteBuf byteBuf = (ByteBuf) msg;
        try {
            byteBuf.readCharSequence(1024, StandardCharsets.UTF_8);
            System.out.println(byteBuf.toString());
        } finally {
            ((ByteBuf) msg).release();
        }
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        final ByteBuf byteBuf = ctx.alloc().buffer(4);
        byteBuf.writeInt((int) (System.currentTimeMillis() / 1000L + 2208988800L));

        final ChannelFuture f = ctx.writeAndFlush(byteBuf);
        f.addListener(new ChannelFutureListener() {
            @Override
            public void operationComplete(ChannelFuture future) throws Exception {
                assert f == future;
                ctx.close();
            }
        });
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}



public class TimeClientInboundHandler extends ChannelInboundHandlerAdapter {
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        ByteBuf byteBuf = (ByteBuf) msg;
        try {
            System.out.println("Client received: " + byteBuf.toString(StandardCharsets.UTF_8));
            ctx.close();
        } finally {
            byteBuf.release();
        }
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) {
        ctx.writeAndFlush(Unpooled.copiedBuffer("What time is it?", StandardCharsets.UTF_8));
    }

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



public class TimeServerInboundHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        ByteBuf byteBuf = (ByteBuf) msg;
        try {
            System.out.println("Server received: " + byteBuf.toString(StandardCharsets.UTF_8));
            String answer = Utils.getCurrentTime();
            ctx.writeAndFlush(Unpooled.copiedBuffer(answer, StandardCharsets.UTF_8));
        } finally {
            ((ByteBuf) msg).release();
        }
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) {
        ctx.writeAndFlush(Unpooled.EMPTY_BUFFER)
                .addListener(ChannelFutureListener.CLOSE);
    }

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



public class Utils {
    public static String getCurrentTime() {
        long currentTimeMillis = ((System.currentTimeMillis() / 1000L + 2208988800L) - 2208988800L) * 1000L;
        return new Date(currentTimeMillis).toString();
    }
}



TimeServerInboundHandler.java


public class TimeClientInboundHandler extends ChannelInboundHandlerAdapter {
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        ByteBuf byteBuf = (ByteBuf) msg;
        try {
            long currentTimeMillis = (byteBuf.readUnsignedInt() - 2208988800L) * 1000L;
            System.out.println(new Date(currentTimeMillis));
            ctx.close();
        } finally {
            byteBuf.release();
        }
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        ctx.write("What time is it?");
        ctx.flush();
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}



public class TimeServerInboundHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        ByteBuf byteBuf = (ByteBuf) msg;
        try {
            byteBuf.readCharSequence(1024, StandardCharsets.UTF_8);
            System.out.println(byteBuf.toString());
        } finally {
            ((ByteBuf) msg).release();
        }
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        final ByteBuf byteBuf = ctx.alloc().buffer(4);
        byteBuf.writeInt((int) (System.currentTimeMillis() / 1000L + 2208988800L));

        final ChannelFuture f = ctx.writeAndFlush(byteBuf);
        f.addListener(new ChannelFutureListener() {
            @Override
            public void operationComplete(ChannelFuture future) throws Exception {
                assert f == future;
                ctx.close();
            }
        });
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}



public class TimeClientInboundHandler extends ChannelInboundHandlerAdapter {
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        ByteBuf byteBuf = (ByteBuf) msg;
        try {
            System.out.println("Client received: " + byteBuf.toString(StandardCharsets.UTF_8));
            ctx.close();
        } finally {
            byteBuf.release();
        }
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) {
        ctx.writeAndFlush(Unpooled.copiedBuffer("What time is it?", StandardCharsets.UTF_8));
    }

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



public class TimeServerInboundHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        ByteBuf byteBuf = (ByteBuf) msg;
        try {
            System.out.println("Server received: " + byteBuf.toString(StandardCharsets.UTF_8));
            String answer = Utils.getCurrentTime();
            ctx.writeAndFlush(Unpooled.copiedBuffer(answer, StandardCharsets.UTF_8));
        } finally {
            ((ByteBuf) msg).release();
        }
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) {
        ctx.writeAndFlush(Unpooled.EMPTY_BUFFER)
                .addListener(ChannelFutureListener.CLOSE);
    }

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



public class Utils {
    public static String getCurrentTime() {
        long currentTimeMillis = ((System.currentTimeMillis() / 1000L + 2208988800L) - 2208988800L) * 1000L;
        return new Date(currentTimeMillis).toString();
    }
}



Utils.java


public class TimeClientInboundHandler extends ChannelInboundHandlerAdapter {
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        ByteBuf byteBuf = (ByteBuf) msg;
        try {
            long currentTimeMillis = (byteBuf.readUnsignedInt() - 2208988800L) * 1000L;
            System.out.println(new Date(currentTimeMillis));
            ctx.close();
        } finally {
            byteBuf.release();
        }
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        ctx.write("What time is it?");
        ctx.flush();
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}



public class TimeServerInboundHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        ByteBuf byteBuf = (ByteBuf) msg;
        try {
            byteBuf.readCharSequence(1024, StandardCharsets.UTF_8);
            System.out.println(byteBuf.toString());
        } finally {
            ((ByteBuf) msg).release();
        }
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        final ByteBuf byteBuf = ctx.alloc().buffer(4);
        byteBuf.writeInt((int) (System.currentTimeMillis() / 1000L + 2208988800L));

        final ChannelFuture f = ctx.writeAndFlush(byteBuf);
        f.addListener(new ChannelFutureListener() {
            @Override
            public void operationComplete(ChannelFuture future) throws Exception {
                assert f == future;
                ctx.close();
            }
        });
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}



public class TimeClientInboundHandler extends ChannelInboundHandlerAdapter {
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        ByteBuf byteBuf = (ByteBuf) msg;
        try {
            System.out.println("Client received: " + byteBuf.toString(StandardCharsets.UTF_8));
            ctx.close();
        } finally {
            byteBuf.release();
        }
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) {
        ctx.writeAndFlush(Unpooled.copiedBuffer("What time is it?", StandardCharsets.UTF_8));
    }

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



public class TimeServerInboundHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        ByteBuf byteBuf = (ByteBuf) msg;
        try {
            System.out.println("Server received: " + byteBuf.toString(StandardCharsets.UTF_8));
            String answer = Utils.getCurrentTime();
            ctx.writeAndFlush(Unpooled.copiedBuffer(answer, StandardCharsets.UTF_8));
        } finally {
            ((ByteBuf) msg).release();
        }
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) {
        ctx.writeAndFlush(Unpooled.EMPTY_BUFFER)
                .addListener(ChannelFutureListener.CLOSE);
    }

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



public class Utils {
    public static String getCurrentTime() {
        long currentTimeMillis = ((System.currentTimeMillis() / 1000L + 2208988800L) - 2208988800L) * 1000L;
        return new Date(currentTimeMillis).toString();
    }
}