序列化机制

虚拟化机制可以将对象转换成字节序列，这些字节序列可以保存在磁盘上
也可以在网络中传输，并允许程序将这些字节序列再次恢复成原来的对象

支持序列化

1. 若对象要支持序列化机制，则他的类需要实现Serializable接口；
2. 该接口是一个标记接口，他没有提供任何方法，只是标记可以序列化
3. java的很多类已经实现Serializable接口 如包装类，String，Date等

实现序列化

使用对象流Objectinputstream和ObjectOutputstream（处理流）

• 序列化
• 1. 创建Objectoutputstream对象
• 2. 调用Objectoutputstream对象的writeObject（）方法，以输出对象序列
• 反序列化
• 1. 创建Objectinputstream对象
• 2. 调用Objectinputstream对象的readObject（）方法。将对象序列恢复为对象

 public static void main(String[] args) {

       testSerialize();
       testDeserialize();
    }

    public static void testSerialize(){

        try (
                ObjectOutputStream oos=new ObjectOutputStream(new FileOutputStream("D:/DXl/FF.txt"))
                ){
            oos.writeObject(new Car("djk","bu",34));

        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    public static void testDeserialize(){

        try (
                ObjectInputStream ois=new ObjectInputStream(new FileInputStream("D:/DXl/FF.txt"))
                ){

            System.err.println(ois.readObject());
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException | ClassNotFoundException e) {
            e.printStackTrace();
        }

    }


}


class Car implements Serializable{

    private String brand;
    private String color;
    private int maxSpeed;

    public Car(String brand, String color, int maxSpeed) {
        System.out.println("Init Car");
        this.brand = brand;
        this.color = color;
        this.maxSpeed = maxSpeed;
    }



    @Override
    public String toString() {
        return "Car{" +
                "brand='" + brand + '\'' +
                ", color='" + color + '\'' +
                ", maxSpeed=" + maxSpeed +
                '}';
    }

序列化规则

序列化的目的是将对象中的数据（成员变量）转为字节序列，和成员方法无关
为了正确地序列化莫个对象，这个对象已经他所对应的类需要符合如下规则

1. 该对象中引用类型的成员变量也必须是可序列化的
2. 该类的直接和间接的父类，要么无参构造器，要么也是可序列化的
3. 一个对象只会被序列化一次，再次序列化时仅仅会输出它的序列号而已
4. 

 public static void main(String[] args) {

       testSerialize();
       testDeserialize();

    }

    public static void testSerialize(){

        try (
                ObjectOutputStream oos=new ObjectOutputStream(new FileOutputStream("D:/DXl/stu.txt"))
        ){

            Teacher t=new Teacher("DJK");
            Student s1=new Student("DXL",t);
            oos.writeObject(t);
            oos.writeObject(s1);


        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    public static void testDeserialize(){

        try (
                ObjectInputStream ois=new ObjectInputStream(new FileInputStream("D:/DXl/stu.txt"))
        ){
            Teacher t= (Teacher) ois.readObject();
            Student s1= (Student) ois.readObject();
            System.out.println(t);
            System.out.println(s1);

        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException | ClassNotFoundException e) {
            e.printStackTrace();
        }

    }



}

class Teacher implements Serializable{

    private String name;

    public Teacher(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

    @Override
    public String toString() {
        return "Teacher{" +
                "name='" + name + '\'' +
                '}';
    }

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


class Student implements Serializable{

    private String name;
    private Teacher teacher;

    public Student(String name, Teacher teacher) {
        this.name = name;
        this.teacher = teacher;
    }

    public String getName() {
        return name;
    }

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

    public Teacher getTeacher() {
        return teacher;
    }

    public void setTeacher(Teacher teacher) {
        this.teacher = teacher;
    }

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