transient 关键字

transient关键字声明的成员变量，在序列化时会被忽略。

public abstract class Main {
    public static void main(String[] args) {
        User user = new User("name", "pwd");
        try (ObjectOutputStream oop = new ObjectOutputStream(new FileOutputStream("user.txt"))) {
            oop.writeObject(user);
        } catch (IOException e) {
            e.printStackTrace();
        }
        User readUser = null;
        try (ObjectInputStream ois = new ObjectInputStream(new FileInputStream("user.txt"))) {
            readUser = (User) ois.readObject();
        } catch (IOException | ClassNotFoundException e) {
            e.printStackTrace();
        }
        if (readUser != null) {
            System.out.println(readUser);         
        }
    }

}

class User implements Serializable {
    String name;
    transient String pwd;

    public User(String name, String pwd) {
        this.name = name;
        this.pwd = pwd;
    }
    @Override
    public String toString() {
        return "User{" +
                "name='" + name + '\'' +
                ", pwd='" + pwd + '\'' +
                '}';
    }
}

输出:

User{name='name', pwd='null'}

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