如何在Parcel的帮助下将一个Parcelable编组和解组为字节数组? [英] How to marshall and unmarshall a Parcelable to a byte array with help of Parcel?

问题描述

我想编组和解编实现到/从字节数组实现Parcelable的类. 我很清楚以下事实:Parcelable表示形式不稳定，因此并不意味着长期存储实例.但是我有一个用例，需要序列化一个对象，并且它不是一个展示对象.如果由于内部Android更改而导致解组失败.而且该类已经在实现Parcelable接口.

I want to marshall and unmarshall a Class that implements Parcelable to/from a byte array. I am well aware of the fact that the Parcelable representation is not stable and therefore not meant for long term storage of instances. But I have a use case where I need to serialize a object and it's not a showstopper if the unmarshalling fails because of an internal Android change. Also the class is already implementing the Parcelable interface.

给定类MyClass implements Parcelable，我如何(ab)使用Parcelable接口进行编组/解组?

Given an class MyClass implements Parcelable, how can I (ab)use the Parcelable interface for marshalling/unmarshalling?

推荐答案

首先创建一个帮助器类 ParcelableUtil.java :

First create a helper class ParcelableUtil.java:

public class ParcelableUtil {    
    public static byte[] marshall(Parcelable parceable) {
        Parcel parcel = Parcel.obtain();
        parceable.writeToParcel(parcel, 0);
        byte[] bytes = parcel.marshall();
        parcel.recycle();
        return bytes;
    }

    public static Parcel unmarshall(byte[] bytes) {
        Parcel parcel = Parcel.obtain();
        parcel.unmarshall(bytes, 0, bytes.length);
        parcel.setDataPosition(0); // This is extremely important!
        return parcel;
    }

    public static <T> T unmarshall(byte[] bytes, Parcelable.Creator<T> creator) {
        Parcel parcel = unmarshall(bytes);
        T result = creator.createFromParcel(parcel);
        parcel.recycle();
        return result;
    }
}

借助上面的util类，您可以像这样编组/解组类MyClass implements Parcelable的实例:

With the help of the util class above, you can marshall/unmarshall instances of your class MyClass implements Parcelable like so:

解组(使用CREATOR)

Unmarshalling (with CREATOR)

byte[] bytes = …
MyClass myclass = ParcelableUtil.unmarshall(bytes, MyClass.CREATOR);

解组(没有CREATOR)

Unmarshalling (without CREATOR)

byte[] bytes = …
Parcel parcel = ParcelableUtil.unmarshall(bytes);
MyClass myclass = new MyClass(parcel); // Or MyClass.CREATOR.createFromParcel(parcel).

编组

MyClass myclass = …
byte[] bytes = ParcelableUtil.marshall(myclass);

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