What are the types of java serialization and deserialization?

Java serialization provides the following types of serialization: 1. Basic data type serialization; 2. Object serialization, which requires the class to implement the java.io.Serializable interface; 3. Externalization and deserialization, which requires the object to implement java .io.Externalizable interface. In actual combat, object information can be directly stored and read.

Types of Java serialization

Java serialization is a method of saving the state of an object to persistent storage or transmitting it over the network the process of. Java provides the following types of serialization:

1. Basic data type serialization

Basic data types (such as int, long, double) can be directly serialized .

// 基本数据类型序列化
int num = 100;
OutputStream out = new FileOutputStream("num.ser");
ObjectOutputStream oos = new ObjectOutputStream(out);
oos.writeObject(num);
oos.close();

2. Object serialization

To serialize objects, the class needs to implement the java.io.Serializable interface.

// 对象序列化
class Person implements Serializable {
    private String name;
    private int age;

    // ...
}

Person person = new Person();
OutputStream out = new FileOutputStream("person.ser");
ObjectOutputStream oos = new ObjectOutputStream(out);
oos.writeObject(person);
oos.close();

3. Externalization and deserialization

Externalization allows customization of the serialization and deserialization process. The object needs to implement the java.io.Externalizable interface.

// 外部化
public void writeExternal(ObjectOutput out) {
    out.writeObject(name);
    out.writeInt(age);
}

// 反序列化
public void readExternal(ObjectInput in) {
    this.name = (String) in.readObject();
    this.age = in.readInt();
}

Practical case

Case: Storing and reading user information

// 存储用户信息
UserInfo user = new UserInfo();
OutputStream out = new FileOutputStream("user.ser");
ObjectOutputStream oos = new ObjectOutputStream(out);
oos.writeObject(user);
oos.close();

// 读取用户信息
ObjectInputStream ois = new ObjectInputStream(new FileInputStream("user.ser"));
UserInfo user2 = (UserInfo) ois.readObject();
ois.close();

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