Netty java从ByteBuf获取数据 [英] Netty java getting data from ByteBuf

问题描述

如何在下面的代码中有效地从 ByteBuf 获取字节数组？我需要获取数组然后序列化它。

How to get a byte array from ByteBuf efficiently in the code below? I need to get the array and then serialize it.

package testingNetty;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;

public class ServerHandler extends  ChannelInboundHandlerAdapter {
     @Override
        public void channelRead(ChannelHandlerContext ctx, Object msg) {
         System.out.println("Message receive");
         ByteBuf buff = (ByteBuf) msg;
             // There is I need get bytes from buff and make serialization
         byte[] bytes = BuffConvertor.GetBytes(buff);
        }

        @Override
        public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) { 
            // Close the connection when an exception is raised.
            cause.printStackTrace();
            ctx.close();
        }

}

推荐答案

ByteBuf buf = ...
byte[] bytes = new byte[buf.readableBytes()];
buf.readBytes(bytes);

如果您不想更改readerIndex：

If you don't want the readerIndex to change:

ByteBuf buf = ...
byte[] bytes = new byte[buf.readableBytes()];
int readerIndex = buf.readerIndex();
buf.getBytes(readerIndex, bytes);

如果要最小化内存副本，可以使用<$ c $的后备数组c> ByteBuf ，如果可用：

If you want to minimize the memory copy, you can use the backing array of the ByteBuf, if it's available:

ByteBuf buf = ...
byte[] bytes;
int offset;
int length = buf.readableBytes();

if (buf.hasArray()) {
    bytes = buf.array();
    offset = buf.arrayOffset();
} else {
    bytes = new byte[length];
    buf.getBytes(buf.readerIndex(), bytes);
    offset = 0;
}

请注意，你不能简单地使用 buf .array（），因为：

Please note that you can't simply use buf.array(), because:

• 并非所有 ByteBuf 有后备阵列。一些是堆外缓冲区（即直接内存）


• 即使 ByteBuf 有一个支持数组（即 buf.hasArray（）返回 true ），以下不一定是真的，因为缓冲区可能是其他缓冲区的一个片段或池化缓冲区：
  
  
  
  
  • buf.array（）[0] == buf.getByte（0）
  
  
  • buf.array（）。length == buf.capacity（）
  
  
  • Not all ByteBufs have backing array. Some are off-heap buffers (i.e. direct memory)
  • Even if a ByteBuf has a backing array (i.e. buf.hasArray() returns true), the following isn't necessarily true because the buffer might be a slice of other buffer or a pooled buffer:
    • buf.array()[0] == buf.getByte(0)
    • buf.array().length == buf.capacity()

    这篇关于Netty java从ByteBuf获取数据的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！