Spring Boot Learning Five: definition of domain

A public class city implements Serializable
Implements the Sericalizable interface, just a sign. Indicates that it can be serialized.

Java's ObjectOutputStream and ObjectInputStream classes enable serialization and deserialization of objects that implement the Serializable interface.

The role of two Serialversionuid
   The serialization mechanism of Java is to verify version consistency by judging the serialversionuid of the class.
   When deserializing, the JVM compares the serialversionuid in the stream to the serialversionuid of the local corresponding entity class, and if the same is considered consistent, it can be deserialized.
   Otherwise, there will be a serialized version inconsistency exception, which is InvalidCastException

Spring Boot Learning Five: definition of domain