[Netty 4 CR2]在使用用户定义的编码器和解码器关闭通道时发生异常

在我的项目中，我将用Netty4替换Netty3。我使用谷歌协议缓冲区作为数据传输。我在关闭频道时遇到了一个异常，它在Netty3中运行良好

以下是例外情况的详细信息：

io.netty.handler.codec.DecoderException: java.lang.IndexOutOfBoundsException: readerIndex(0) + length(4) exceeds writerIndex(0): PooledUnsafeDirectByteBuf(ridx: 0, widx: 0, cap: 4096)
    at io.netty.handler.codec.ByteToMessageDecoder.channelInactive(ByteToMessageDecoder.java:95)
    at io.netty.channel.DefaultChannelHandlerContext.invokeChannelInactive(DefaultChannelHandlerContext.java:801)
    at io.netty.channel.DefaultChannelHandlerContext.fireChannelInactive(DefaultChannelHandlerContext.java:787)
    at io.netty.channel.DefaultChannelPipeline.fireChannelInactive(DefaultChannelPipeline.java:808)
    at io.netty.channel.AbstractChannel$AbstractUnsafe$9.run(AbstractChannel.java:725)
    at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:364)
    at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:326)
    at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:114)
    at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.IndexOutOfBoundsException: readerIndex(0) + length(4) exceeds writerIndex(0): PooledUnsafeDirectByteBuf(ridx: 0, widx: 0, cap: 4096)
    at io.netty.buffer.AbstractByteBuf.checkReadableBytes(AbstractByteBuf.java:1120)
    at io.netty.buffer.AbstractByteBuf.readInt(AbstractByteBuf.java:627)
    at com.fhq.mathematica.netty.MMADecoder.decode(MMADecoder.java:17)
    at io.netty.handler.codec.ByteToMessageDecoder.decodeLast(ByteToMessageDecoder.java:168)
    at io.netty.handler.codec.ByteToMessageDecoder.channelInactive(ByteToMessageDecoder.java:91)

这是编码器：（消息是顶层协议缓冲区的接口。）

有人能解决这个问题吗？非常感谢

---

顺便说一句：我试过ObjectEncoder和ObjectDecoder，然后一切都很好。因此，我的解码器/编码器中一定存在一些问题。

在调用ByteBuf.readInt（）之前，您需要检查是否有足够的字节可以读取

比如说：

public class MMADecoder extends ByteToMessageDecoder{
    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf in,
            MessageBuf<Object> out) throws Exception {
        if (in.readableBytes < 4) {
            return;
        }
        in.markReaderIndex();
        int dataLength = in.readInt();
        if (in.readableBytes() < dataLength) {
            in.resetReaderIndex();
            return;
        }
        byte[] decoded = new byte[dataLength];
        in.readBytes(decoded);
        out.add(MathematicaTask.parseFrom(decoded));
    }
}

公共类MMADecoder扩展为teToMessageDecoder{
@凌驾
受保护的无效解码（ChannelHandlerContext ctx、ByteBuf in、，
MessageBuf out）抛出异常{
if（in.readableBytes<4）{
返回；
}
in.markReaderIndex（）；
int dataLength=in.readInt（）；
if（in.readableBytes（）

谢谢！它起作用了！但是为什么我们要将可读字节与4进行比较呢？如果你有时间的话，你能看看这个问题吗？非常感激。[连结]

public class MMADecoder extends ByteToMessageDecoder{
    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf in,
            MessageBuf<Object> out) throws Exception {
        in.markReaderIndex();
        int dataLength = in.readInt();
        if (in.readableBytes() < dataLength) {
            in.resetReaderIndex();
            return;
        }
        byte[] decoded = new byte[dataLength];
        in.readBytes(decoded);
        out.add(MathematicaTask.parseFrom(decoded));
    }
}

int dataLength = in.readInt();

public class MMADecoder extends ByteToMessageDecoder{
    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf in,
            MessageBuf<Object> out) throws Exception {
        if (in.readableBytes < 4) {
            return;
        }
        in.markReaderIndex();
        int dataLength = in.readInt();
        if (in.readableBytes() < dataLength) {
            in.resetReaderIndex();
            return;
        }
        byte[] decoded = new byte[dataLength];
        in.readBytes(decoded);
        out.add(MathematicaTask.parseFrom(decoded));
    }
}