Netty实现Unity登录验证(二)

这里主要处理二进制消息的粘包拆包

package com.netty.decoder;

import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
/*
*后面我们在Socket Channel中移除二进制消息的前四个字节
*ch.pipeline().addLast(new LengthDecoder(1024, 0, 4, 0, 4));
*/
public class LengthDecoder extends LengthFieldBasedFrameDecoder {
  
  /*
  *maxFrameLength：解码的最大长度
  *lengthFieldOffset ：长度属性的起始位（偏移位），存放有整个数据包长度的字节位置
  *lengthFieldLength：长度属性的长度，即存放整个大数据包长度的字节所占的长度
  *lengthAdjustmen：长度调节值，在总长被定义为含包头长度时，修正信息长度
  *initialBytesToStrip：跳过的字节数，根据需要我们跳过lengthFieldLength个字节，
  *                     以便接收端直接接受到不含“长度属性”的内容
  */
  public LengthDecoder(int maxFrameLength, int lengthFieldOffset, 
      int lengthFieldLength,  int lengthAdjustment, 
      int initialBytesToStrip)
  {
    super(maxFrameLength, lengthFieldOffset,
        lengthFieldLength, lengthAdjustment,
        initialBytesToStrip);    
  }
}

package com.netty.decoder;

import java.util.List;

import com.dyuproject.protostuff.ProtobufIOUtil;
import com.dyuproject.protostuff.Schema;
import com.dyuproject.protostuff.runtime.RuntimeSchema;
import com.netty.model.SocketModel;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;

/*
*把二进制转化成我们的协议消息SocketModel类型。
*/

public class MessageDecoder extends ByteToMessageDecoder {

  private Schema<SocketModel> schema = RuntimeSchema
      .getSchema(SocketModel.class);// protostuff的写法，通过对象的类构建对应的schema

  @Override
  protected void decode(ChannelHandlerContext ctx, ByteBuf in,
      List<Object> obj) throws Exception {

    byte[] data = new byte[in.readableBytes()];
    in.readBytes(data);
    SocketModel message = new SocketModel();
    ProtobufIOUtil.mergeFrom(data, message, schema);  //反序列化  
    obj.add(message);
  }
}

package com.netty.encoder;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToByteEncoder;
import com.dyuproject.protostuff.LinkedBuffer;
import com.dyuproject.protostuff.ProtobufIOUtil;
import com.dyuproject.protostuff.Schema;
import com.dyuproject.protostuff.runtime.RuntimeSchema;
import com.netty.model.SocketModel;
import com.netty.util.CoderUtil;

public class MessageEncoder extends MessageToByteEncoder<SocketModel> {

  private Schema<SocketModel> schema = RuntimeSchema
      .getSchema(SocketModel.class);

  protected void encode(ChannelHandlerContext ctx, SocketModel message,
      ByteBuf out) throws Exception {
    
    LinkedBuffer buffer = LinkedBuffer.allocate(1024);
    byte[] data = ProtobufIOUtil.toByteArray(message, schema, buffer);  
    
    ByteBuf buf = Unpooled.copiedBuffer(CoderUtil.intToBytes(data.length),
        data); // 在写消息之前需要把消息的长度添加到投4个字节
    
    out.writeBytes(buf);
  }
}