Java序列化

序列化:将对象转换为字节序列的过程

反序列化:将字节序列转换为对象的过程

原因:转换为字节序列后,保存字节码文件,方便网络的传输。

Java序列化_第1张图片

 

 

 Person类

package demo1.serializable;

import java.io.Serializable;

public class Person implements Serializable {


    public int id;
    private static final long serialVersionUID = 1L;
//    private static final long serialVersionUID = 2L;
    public Person(int id) {
        this.id = id;
    }


}

Test测试类

package demo1.serializable;

import java.io.*;

public class Test {

    public static void serializablePerson(Person person) throws IOException {
        ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("file.txt"));
        out.writeObject(person);
        System.out.println("序列化成功");
        out.close();
    }

    public static Person deserializablePerson(String filePath) throws IOException, ClassNotFoundException {
        ObjectInputStream in = new ObjectInputStream(new FileInputStream(filePath));
        System.out.println("反序列化成功");
        return (Person)in.readObject();
    }
    public static void main(String[] args) throws IOException, ClassNotFoundException {
        Person per = new Person(1);
        serializablePerson(per);
//        System.out.println(deserializablePerson("file.txt"));
    }
}
以上序列化、反序列化都成功!

皮一下-1!
1.序列化时设置序列化ID
private static final long serialVersionUID = 1L;
2.修改Person类的序列化ID,进行反序列化
private static final long serialVersionUID = 2L;
最终结果:
Exception in thread "main" java.io.InvalidClassException: demo1.serializable.Person; local class incompatible: stream classdesc serialVersionUID = 1, local class serialVersionUID = 2
    at java.io.ObjectStreamClass.initNonProxy(ObjectStreamClass.java:699)
    at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1885)
    at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1751)
    at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2042)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1573)
    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:431)
    at demo1.serializable.Test.deserializablePerson(Test.java:17)
    at demo1.serializable.Test.main(Test.java:22)
 
 

由此证明:反序列化时:序列化ID不对,是无法序列化成功的。

再皮一下-2

1.序列化时设置序列化ID
private static final long serialVersionUID = 1L;
2.给Person添加属性int age,再反序列化
最终结果:
反序列化成功
Person{id=1, age=0}

害,也就是说,序列化ID是一样的就是无敌咯!!!

再皮一下下-3

1.颠倒id、age的位置

Java序列化_第2张图片

 

 没得用,仔细想想也是没用的,nt了。

突发奇想:反序列化的时候到底是怎么找到对应的字段并赋值的,是构造方法的顺序,还是名字!

1.修改构造方法

序列化时,Person类如下:

package demo1.serializable;

import java.io.Serializable;

public class Person implements Serializable {


    public String name;
    public int id;
    private static final long serialVersionUID = 1L;
    public Person(int id) {
        this.id = id;
    }

    @Override
    public String toString() {
        return "Person{" +
                "id=" + id +
                ", name=" + name +
                '}';
    }
}

反序列化时,Person类如下:

package demo1.serializable;

import java.io.Serializable;

public class Person implements Serializable {


    public String name;
    public int id;
    private static final long serialVersionUID = 1L;
    public Person(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "Person{" +
                "id=" + id +
                ", age=" + id +
                '}';
}

Java序列化_第3张图片

 

由此证明:反序列化,是通过属性名来找到对应的属性值来反序列化的!!!
另外:
序列化使用:ObjectOutputStream类
反序列化使用:ObjectInputStream类


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