Deserialization in Java is the process of converting a serialized byte stream (i.e., a sequence of bytes read from persistent storage) back into its original object form. Serialization is the process of converting an object into a byte sequence for storage (e.g., in a file system) or network transmission. Deserialization is the inverse of serialization, restoring the object from the byte sequence.
For example, consider a client-server application where the server needs to send a Date object to the client representing the current date and time. The server serializes the Date object into a byte sequence and transmits it over the network to the client. Upon receiving these bytes, the client uses the deserialization process to convert them back into a Date object, enabling the client program to handle and utilize the date information in object form.
Security Issues
Note that deserialization can introduce security risks. If the input data source is untrusted, malicious payloads may exploit the deserialization process to execute code or crash the application. Therefore, when handling deserialization, ensure the data source is trusted or implement additional validation measures to secure the data.