serialVersionUID是干什么用的

序列化

使Java的对象可以序列化, 但是为什么需要这个id呢. 这个序列化的对象, 在写入(序列化)和读取(反序列化)的时候有可能存在差异. 那么Java就用这个serialVersionUID值是否相同来判断序列化的对象是否一致. 如果两个对象的serialVersionUID都不一致, 那肯定就没办法序列化了.

例子

import java.io.Serializable;

public class Person implements Serializable {

    private static final long serialVersionUID = 7371845487964803604L;

    private String          name;

    private int             id;

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

    public String getName() {
        return name;
    }

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

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

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

序列化

import java.io.*;

public class DeserialTest {

    public static void main(String[] args) throws IOException, ClassNotFoundException {
        Person person;
        FileInputStream fileInputStream = new FileInputStream("person.txt");
        ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);
        person = (Person)objectInputStream.readObject();
        System.out.println(person);
    }
}

反序列化

import java.io.*;

public class DeserialTest {

    public static void main(String[] args) throws IOException, ClassNotFoundException {
        Person person;
        FileInputStream fileInputStream = new FileInputStream("person.txt");
        ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);
        person = (Person)objectInputStream.readObject();
        System.out.println(person);
    }
}