java 07 对象序列化流

2.8serialVersionUID&transient【应用】

• serialVersionUID

  • 用对象序列化流序列化了一个对象后，假如我们修改了对象所属的类文件，读取数据会不会出问题呢？

    • 会出问题，会抛出InvalidClassException异常

  • 如果出问题了，如何解决呢？

    • 重新序列化

    • 给对象所属的类加一个serialVersionUID

      • private static final long serialVersionUID = 42L;

• transient

  • 如果一个对象中的某个成员变量的值不想被序列化，又该如何实现呢？

    • 给该成员变量加transient关键字修饰，该关键字标记的成员变量不参与序列化过程

• 示例代码

package duixiangxuliehua;

import java.io.Serial;
import java.io.Serializable;

public class Student implements Serializable {
    @Serial
    // 显示序列化id
    private static final long serialVersionUID = 42L;
    private String name;
    // private int age;
    // 不参与序列化
    private transient int age;

    public Student() {
    }

    public Student(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

/*    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }*/
}

package duixiangxuliehua;

import java.io.*;

public class demo1 {
    public static void main(String[] args) throws IOException, ClassNotFoundException {
        // write();
        read();
    }

    public static void write() throws IOException {
        ObjectOutputStream oo = new ObjectOutputStream(new FileOutputStream("stu\\src\\duixiangxuliehua\\demo.txt"));

        Student s = new Student("林青霞",30);

        oo.writeObject(s);

        oo.close();
    }

    public static void read() throws IOException, ClassNotFoundException {
        ObjectInputStream ois = new ObjectInputStream(new FileInputStream("stu\\src\\duixiangxuliehua\\demo.txt"));
        Object o = ois.readObject();
        Student s = (Student) o;
        System.out.println(s.getName()+s.getAge());
        ois.close();
    }
}