Java序列化与Serializable（一）OverView

最新推荐文章于 2022-07-06 09:59:39 发布

perfectnihil

最新推荐文章于 2022-07-06 09:59:39 发布

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本文介绍了序列化和反序列化的概念，即把数据结构或对象转换为便于存储、传输和重构的格式，反向操作则为反序列化。还阐述了Java中实现序列化的方法，即实现Serializable接口。此外，强调了手动申明serialVersionUID以保证兼容性，避免因类字段变动导致的错误。

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参考：https://en.wikipedia.org/wiki/Serialization

1.什么是序列化和反序列化

In computer science, in the context of data storage, serialization (or serialisation) is the process of translating data structures or object state into a format that can be stored (for example, in a file or memory buffer) or transmitted (for example, across a network connection link) and reconstructed later (possibly in a different computer environment)

翻译：序列化，就是把数据结构或者对象转换到一种便于存储，传输，以及重reconstructed 的格式的过程

When the resulting series of bits is reread according to the serialization format, it can be used to create a semantically identical clone of the original object

翻译：当resulting series of bits 被按照序列或的格式重新读取后，这个可以来创建一个最初的对象的语义上完全的clone

点评：突然想到有些科幻小说中，把人粒子化，然后光速传播到另一个地方，再重新reconstructed。感觉有点相似。

For many complex objects, such as those that make extensive use of references, this process is not straightforward.

翻译：对一些复杂的对象，比如有大量应用，这个过程就不那么简单了。

Serialization of object-oriented objects does not include any of their associated methods with which they were previously linked.

翻译：面向对象的对象不包括之前和他们相关联的方法。

This process of serializing an object is also called marshalling an object.[2] The opposite operation, extracting a data structure from a series of bytes, is deserialization (also called unmarshalling).

翻译：序列化过程也叫marshalling an object 。反方向的操作，叫做反序列化（也叫作 unmarshalling）

2.java中如何实现序列化

Java中实现序列化只要实现Serializable接口即可

举例：TestBean类（如果是在android中主要要申请读写权限）

public class TestBean implements Serializable {
    public String desc;
    public String property1;
    public String property2;

    @Override
    public String toString() {
        return "TestBean{" +
                "desc='" + desc + '\'' +
                ", property1='" + property1 + '\'' +
                ", property2='" + property2 + '\'' +
                '}';
    }
}

序列化以及反序列化的方法

 public void serialization(View view) {
        try {

            TestBean testBean = new TestBean();
            testBean.property1 = "属性1";
            testBean.property2 = "属性2";
            testBean.desc = "我是testbean";

            ObjectOutputStream objectOutputStream = new ObjectOutputStream(new FileOutputStream("/sdcard/aaatest.txt"));
            objectOutputStream.writeObject(testBean);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void deserialization(View view) {
        ObjectInputStream objectInputStream = null;
        try {
            objectInputStream = new ObjectInputStream(new FileInputStream("/sdcard/aaatest.txt"));
            TestBean testBean = (TestBean) objectInputStream.readObject();
            Log.i(TAG,"deserialization"+testBean.toString());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

查看aaatest.txt 文件，里面有一些乱码

 sr calc.superdy.ttest.test.TestBean`仍旾?C L desct Ljava/lang/String;L property1q ~ L property2q ~ xpt 鎴戞槸testbeant 灞炴€?t 灞炴€?

经过上面的测试，序列化到文件中的对象通过反序列化过程可以正常读取

3.关于serialVersionUID

如果实现序列化了的类中有字段变动，切没有主动申明 serialVersionUID ，则系统会自动生成一个serialVersionUID

所以为了兼容，还是要自己手动申明 serialVersionUID

例如：写的时候是这样的结构

public class TestBean  implements Serializable {
    public String desc;
    public String property1;
    public String property2;

//    public static final int serialVersionUID = 1;
    @Override
    public String toString() {
        return "TestBean{" +
                "desc='" + desc + '\'' +
                ", property1='" + property1 + '\'' +
                ", property2='" + property2 + '\'' +
                '}';
    }
}

读的时候

public class TestBean  implements Serializable {
    public String desc;
    public String property1;
    public String property2;
    public String property3;
//    public static final int serialVersionUID = 1;
    @Override
    public String toString() {
        return "TestBean{" +
                "desc='" + desc + '\'' +
                ", property1='" + property1 + '\'' +
                ", property2='" + property2 + '\'' +
                '}';
    }
}

则会报如下错误：

/System.err: java.io.InvalidClassException: calc.superdy.ttest.test.TestBean; local class incompatible: stream classdesc serialVersionUID = 6974057760637855555, local class serialVersionUID = -1037588103870301871