标签：java name age Fox 理解 new 序列化 public

我对java序列化的理解

通过ObjectOutputStream输出流保存实体类所产生的文件，每一个流都一个序列化ID，如果我们不设置UID的话，一旦我们修改代码，这个文件就会出现InvalidClassException异常，所以需要设置一个私有静态最终类的UID，这样才能保证我们的流不能被找到。

演示代码

第一步/编写Student实体类代码

/**
 * @author Mxhlin
 * @Email fuhua277@163.com
 * @Date 2022/09/24/8:17
 * @Version
 * @Description 狐狸实体类 有一个名字 年龄的属性，toString/Get/Set/有/无参构造方法
 */
public class Fox {
    private String name;
    private int age;

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

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

    public Fox() {
    }
}

第二步/编写序列化代码

package com.Mxhlin.io;

import java.io.*;
import java.util.ArrayList;
import java.util.List;

/**
 * @author Mxhlin
 * @Email fuhua277@163.com
 * @Date 2022/09/24/8:21
 * @Version
 * @Description 序列化Fox
 */
public class FoxSeria {
    static String db = "db.dat";

    static {// 初始化一个空元素
        if (!new File(db).exists()) {
            try (ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("db"))) {
                List<Fox> list = new ArrayList<>();
                oos.writeObject(list);
            } catch (FileNotFoundException e) {
                throw new RuntimeException(e);
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
    }

    public static void main(String[] args) {
        // 第一次查询
        System.out.println(rand());
    }


    /**
     * @Description: 读取db.dat
     * @Param: []
     * @return: java.util.List<com.Mxhlin.io.Fox>
     * @Author: Mxhlin
     * @Date: 2022/9/24
     */
    public static List<Fox> rand() {
        List<Fox> list = new ArrayList<>();
        try (ObjectInputStream ois = new ObjectInputStream(new FileInputStream(db))) {
            list = (List<Fox>) ois.readObject();
        } catch (FileNotFoundException e) {
            throw new RuntimeException(e);
        } catch (IOException e) {
            throw new RuntimeException(e);
        } catch (ClassNotFoundException e) {
            throw new RuntimeException(e);
        }
        return list;
    }

    /**
     * @Description: 输出文件
     * @Param: [fox]
     * @return: int
     * @Author: Mxhlin
     * @Date: 2022/9/24
     */
    public static int write(Fox fox) {
        List<Fox> list = new ArrayList<>();
        list.add(fox);
        int i = 0;
        try (ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(db))) {
            oos.writeObject(list);
            i = 1;
        } catch (FileNotFoundException e) {
            throw new RuntimeException(e);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
        return i;
    }
}