java序列化反序列化的类型有哪些？

// 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();

// 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();

// 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();
}

// 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();