将串行化的对象通过对象流写入文件或传送到其他地方。对象流是在普通流上加了传输对象的功能，所以构造对象流时要先构造普通文件流。-Serialized object will flow through the object to write the file or send to other places. Object flow is added in the general flow of the transmission function of the object, so when the