说明：  protocolbuffer(以下简称PB)是google 的一种数据交换的格式，它独立于语言，独立于平台。google 提供了多种语言的实现：java、c#、c++、go 和 python，每一种实现都包含了相应语言的编译器以及库文件。由于它是一种二进制的格式，比使用 xml 进行数据交换快许多。可以把它用于分布式应用之间的数据通信或者异构环境下的数据交换。作为一种效率和兼容性都很优秀的二进制数
(Protocolbuffer (hereinafter referred to as PB) is a data exchange format of Google. It is independent of language and independent of platform. Google provides multiple language implementations: Java, c#, c++, go, and python, each of which includes compilers and library files for the corresponding language. Because it's a binary format, it's much faster than using XML for data exchange. It can be used for data communication between distributed applications or data exchange in heterogeneous environments. Binary numbers that are excellent for both efficiency and compatibility)