code: @Override
  	public byte[] getAppIdFloor(String appId) {
  
  		int appIdCode = codecer.findId(APP_ID, appId).intValue();
  		ByteBuffer byteBuffer = ByteBuffer.allocate(12);
  		putUnsignedShort(byteBuffer, appIdCode);
  		putUnsignedShort(byteBuffer, 0);
  		putUnsignedShort(byteBuffer, 0);
  		putUnsignedShort(byteBuffer, 0);
  		putUnsignedShort(byteBuffer, 0);
  		putUnsignedShort(byteBuffer, 0);
  		
  		return byteBuffer.array();
  	}
docs: /* (non-Javadoc)
  @see com.yiqiniu.easytrans.util.ByteFormIdCodec#getAppIdFloor(java.lang.String)