java对象序列化

java对象序列化

用于网络传输该对象

要序列化的对象Person

序列化的对象必须实现 Serializable接口, 否则序列化会报错

class Person implements Serializable {
    String name = "Li";
    int age = 10;

    public Person() {
    }

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

    public void show() {
        System.out.println("this is the show 方法!!");
    }

    public void printInfo() {
        System.out.println("姓名是: " + name + " 年龄是: " + age);
    }
}

序列化过程

使用 new ObjectOutputStream 进行写入到文件中

public static void main(String[] args) {
	FileOutputStream fileOutputStream = new FileOutputStream("D:\\java_project\\jpa-test\\src\\main\\java\\com\\example\\controller\\b.txt");
    new ObjectOutputStream(fileOutputStream).writeObject(new Person("Person-name",22));
}

序列化后的文件打开内容如下:

反序列化过程

public static void main(String[] args) {
    ObjectInputStream objectInputStream = new ObjectInputStream(new FileInputStream("D:\\java_project\\jpa-test\\src\\main\\java\\com\\example\\controller\\b.txt"));
    Person person = (Person) objectInputStream.readObject();

    System.out.println(person.age);
    System.out.println(person.name);
    person.show();
    person.printInfo();
}

打印结果:

如果序列化后修改了原始对象Person,如,新增加了一个方法, 则反序列化失败

class Person implements Serializable {
    String name = "Li";
    int age = 10;

    public Person() {
    }

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

    public void show() {
        System.out.println("this is the show 方法.");
    }

    public void printInfo() {
        System.out.println("姓名是: " + name + " 年龄是: " + age);
    }
    
    //新增了一个方法
    public void addNewFunc() {
        System.out.println("添加了一个新方法...");
    }
}

反序列化失败:

如果想确保在序列化后,修改序列化对象后, 在反序列化时不报错, 需要序列化对象加上

private static final long serialVersionUID = 64623316465L;

现在Person类如下:

class Person implements Serializable {
    
    //加上序列化号
    private static final long serialVersionUID = 64623316465L;

    String name = "Li";
    int age = 10;

    public Person() {
    }

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

    public void show() {
        System.out.println("this is the show 方法.");
    }

    public void printInfo() {
        System.out.println("姓名是: " + name + " 年龄是: " + age);
    }

    public void addNewFunc() {
        System.out.println("添加了一个新方法...");
    }
}

现在再次序列化后,再修改Person对象,然后再反序列化就不会报错了