安卓ResolveInfo可打包不是完全不打包的

Question

我遇到了一件我本以为很简单的任务，那就是将一个ResolveInfo对象写到一个包中，然后从这个包中创建一个ResolveInfo。不幸的是，这并不是因为我的代码崩溃并抛出一个java.lang.IllegalStateException。

以下是我的代码

fun failingFunction(resolveInfo:ResolveInfo){
    Log.d(TAG,"original label ${resolveInfo.loadLabel(this.packageManager)}")
    val p = Parcel.obtain()
    resolveInfo.writeToParcel(p, 0)
    val copy = ResolveInfo.CREATOR.createFromParcel(p)
    Log.d(TAG,"copy label ${copy.loadLabel(this.packageManager)}") // throws java.lang.IllegalStateException: Missing ComponentInfo!
}

查看ResolveInfo类的源代码，当ResolveInfo ActivityInfo、ServiceInfo或ProviderInfo属性都不存在时，就会抛出异常。因此，我添加了日志，以检查这些日志是否丢失。

fun failingFunction(resolveInfo:ResolveInfo){
    Log.d(TAG,"original activity info ${resolveInfo.activityInfo}")
    Log.d(TAG,"original service info ${resolveInfo.serviceInfo}")
    Log.d(TAG,"original provider info ${resolveInfo.providerInfo}")
    Log.d(TAG,"original label ${resolveInfo.loadLabel(this.packageManager)}")
    val p = Parcel.obtain()
    resolveInfo.writeToParcel(p, 0)
    val copy = ResolveInfo.CREATOR.createFromParcel(p)
    Log.d(TAG,"copy activity info ${copy.activityInfo}")
    Log.d(TAG,"copy service info ${copy.serviceInfo}")
    Log.d(TAG,"copy provider info ${copy.providerInfo}")
    Log.d(TAG,"copy label ${copy.loadLabel(this.packageManager)}")
}

我的原始ResolveInfo对象有一个ActivityInfo，但我的副本没有。ActivityInfo实现了Parcelable，所以我不太理解为什么它没有写在Parcel中。根据ResolveInfo的来源，它应该写在包裹中，并从其中读取：

public void writeToParcel(Parcel dest, int parcelableFlags) {
    if (activityInfo != null) {
        dest.writeInt(1);
        activityInfo.writeToParcel(dest, parcelableFlags);
    } else if (serviceInfo != null) {
        dest.writeInt(2);
        serviceInfo.writeToParcel(dest, parcelableFlags);
    } else if (providerInfo != null) {
        dest.writeInt(3);
        providerInfo.writeToParcel(dest, parcelableFlags);
    } else {
        dest.writeInt(0);
    }
    if (filter != null) {
        dest.writeInt(1);
        filter.writeToParcel(dest, parcelableFlags);
    } else {
        dest.writeInt(0);
    }
    dest.writeInt(priority);
    dest.writeInt(preferredOrder);
    dest.writeInt(match);
    dest.writeInt(specificIndex);
    dest.writeInt(labelRes);
    TextUtils.writeToParcel(nonLocalizedLabel, dest, parcelableFlags);
    dest.writeInt(icon);
    dest.writeString(resolvePackageName);
    dest.writeInt(targetUserId);
    dest.writeInt(system ? 1 : 0);
    dest.writeInt(noResourceId ? 1 : 0);
    dest.writeInt(iconResourceId);
    dest.writeInt(handleAllWebDataURI ? 1 : 0);
    dest.writeInt(isInstantAppAvailable ? 1 : 0);
}

private ResolveInfo(Parcel source) {
    activityInfo = null;
    serviceInfo = null;
    providerInfo = null;
    switch (source.readInt()) {
        case 1:
            activityInfo = ActivityInfo.CREATOR.createFromParcel(source);
            break;
        case 2:
            serviceInfo = ServiceInfo.CREATOR.createFromParcel(source);
            break;
        case 3:
            providerInfo = ProviderInfo.CREATOR.createFromParcel(source);
            break;
        default:
            Slog.w(TAG, "Missing ComponentInfo!");
            break;
    }
    if (source.readInt() != 0) {
        filter = IntentFilter.CREATOR.createFromParcel(source);
    }
    priority = source.readInt();
    preferredOrder = source.readInt();
    match = source.readInt();
    specificIndex = source.readInt();
    labelRes = source.readInt();
    nonLocalizedLabel
            = TextUtils.CHAR_SEQUENCE_CREATOR.createFromParcel(source);
    icon = source.readInt();
    resolvePackageName = source.readString();
    targetUserId = source.readInt();
    system = source.readInt() != 0;
    noResourceId = source.readInt() != 0;
    iconResourceId = source.readInt();
    handleAllWebDataURI = source.readInt() != 0;
    instantAppAvailable = isInstantAppAvailable = source.readInt() != 0;
}

有没有人知道为什么这个嵌套的Parcelable没有正确解包？我是否遗漏了我应该使用的有用标志？

谢谢,

Answer 1

好了，我已经找到了解决问题的方法，它与Parcelable Creator方法无关，而是与我使用Parcel的方式有关。一旦你完成了在包中的编写，你就必须以0作为参数值来调用setDataPosition。

我的代码现在如下：

fun failingFunction(resolveInfo:ResolveInfo){
    Log.d(TAG,"original label ${resolveInfo.loadLabel(this.packageManager)}")
    val p = Parcel.obtain()
    resolveInfo.writeToParcel(p, 0)
    p.setDataPosition(0)
    val copy = ResolveInfo.CREATOR.createFromParcel(p)
    Log.d(TAG,"copy label ${copy.loadLabel(this.packageManager)}") // no longer throws java.lang.IllegalStateException
}