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This article introduces the relevant knowledge of "introduction of knowledge points of java serialization". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

Serialization is the process of converting the state information of an object into a form that can be stored or transmitted. So serialization is a very important part of Java development. Java serialization can save (persist) defined objects after JVM stops running, and reread the saved objects in the future.

With Java object serialization, when an object is saved, its state is saved as a set of bytes, which are then assembled into objects in the future. It must be noted that object serialization holds the "state" of the object, that is, its member variables. From this, object serialization does not care about static variables in the class.

How to serialize

As long as a class implements the java.io.Serializable interface, it can be serialized.

Serialversionuid action

SerialVersionUID applies to the serialization mechanism of Java. To put it simply, the serialization mechanism of Java verifies version consistency by judging the serialVersionUID of the class. When deserializing, JVM compares the serialVersionUID in the incoming byte stream with the serialVersionUID of the corresponding local entity class. If the same is considered to be consistent, it can be deserialized, otherwise there will be an exception of inconsistent serialization version, that is, InvalidCastException.

How to produce serialversionuid

In eclipse or idea, when the Serializable interface is implemented, there will be a small yellow exclamation point at the left end of the corresponding line. Click and select generaterd serial version ID to produce the id shown in the figure.

Private static final long serialVersionUID = 1518830894504324355L

Code example

Knowledge of serialization and deserialization

1. In Java, as long as a class implements the java.io.Serializable interface, it can be serialized.

2. Rely on ObjectOutputStream and ObjectInputStream to serialize and deserialize objects

3. Whether the virtual machine allows deserialization depends not only on whether the classpath and function code are consistent, but also on whether the serialization ID of the two classes is consistent (that is, private static final long serialVersionUID).

4. Serialization does not save static variables.

5. If you want to serialize the parent object, you need to have the parent class also implement the Serializable interface.

6. The function of the Transient keyword is to control the serialization of the variable. Adding the keyword before the variable declaration can prevent the variable from being serialized into the file. After being deserialized, the value of the transient variable is set to the initial value, such as the int type is 0 and the object type is null.

7. The server sends serialized object data to the client, and some of the data in the object is sensitive, such as a password string. It is hoped that the password field will be encrypted when serialized, and if the client has a decryption key, the password can be read only when the client is deserialized, which can ensure the data security of the serialized object to a certain extent.

This is the end of the introduction to java serialization. Thank you for your reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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