使用Android读取OBB文件内容时出错

Question

我使用OBB保存数据，需要使用Android访问数据。但是，我似乎不能挂载obb文件来检索数据。根据APK扩展文件文档的说法，我用这个计划来命名我的目标。

例如，main.1.com.example.native_activity.obb

然后，我将其放在/data/Android/obb/com.example.本会_activity文件夹下，这是上面的在线文档所建议的。

但是，通过使用以下代码，我无法进行obb挂载：

AStorageManager* man = AStorageManager_new();
char* data = malloc(256);
AStorageManager_mountObb(man, "main.1.com.example.native_activity.obb", "somekey", my_obbCallbackFunc, data);
char* obbPath = AStorageManager_getMountedObbPath(man, "main.1.com.example.native_activity.obb");

LOGI("mounted path: %s", obbPath);
free(data);
data = NULL;
AStorageManager_delete(man);
man = NULL;

结果证明，obbPath始终是空的。我不知道如何得到正确的钥匙，所以这只是随机化。

更新

我从我这边纠正了两个问题。

首先，obb文件不是使用Android工具创建的，而是从zip文件中重命名的。因此，我使用以下方法重新创建了文件：

jobb -d assets/ -o obb/main.1.com.example.native_activity.obb -k mykey -pn com.example.native_activity -pv 11

把它推到下面

/sdcard/Android/obb/com.example.native_activity/

然后，我在mountObb调用中使用了键和回调函数，代码如下：

char obbPath[256];
sprintf(obbPath, "/sdcard/Android/obb/com.example.native_activity/main.1.com.example.native_activity.obb");
struct stat sts;
if(stat(obbPath, &sts) == -1)
{
    LOGI("File not found: %s\n", obbPath);
}
else
{
    LOGI("File found: %s", obbPath);
}

AStorageManager* man = AStorageManager_new();
char* data = malloc(256);
AStorageManager_mountObb(man, obbPath, "mykey", my_obbCallbackFunc, data);
char* mntPath = AStorageManager_getMountedObbPath(man, obbPath);

int isMounted = AStorageManager_isObbMounted(man, obbPath);

LOGI("mounted path: %s, already mounted?: %d", mntPath, isMounted);
free(data);
data = NULL;
AStorageManager_delete(man);
man = NULL;
return 1;

和回调

void my_obbCallbackFunc(const char* filename, const int32_t state, void* data)
{
    LOGI("my_obbCallbackFunc: %d", state);
}

我得到的Logcat输出：

08-09 08:45:15.960: I/native-activity(9166): Touched screen.
08-09 08:45:15.960: I/native-activity(9166): File found: /sdcard/Android/obb/com.example.native_activity/main.1.com.example.native_activity.obb
08-09 08:45:15.960: E/Parcel(9166): Reading a NULL string not supported here.
08-09 08:45:15.960: I/native-activity(9166): mounted path: , already mounted?: 0
08-09 08:45:15.970: I/native-activity(9166): Touched screen.
08-09 08:45:15.970: I/native-activity(9166): File found: /sdcard/Android/obb/com.example.native_activity/main.1.com.example.native_activity.obb
08-09 08:45:15.970: E/Parcel(9166): Reading a NULL string not supported here.
08-09 08:45:15.970: I/native-activity(9166): mounted path: , already mounted?: 0
08-09 08:45:16.030: I/native-activity(9166): my_obbCallbackFunc: 1
08-09 08:45:16.030: I/native-activity(9166): my_obbCallbackFunc: 24
08-09 08:45:16.030: I/native-activity(9166): my_obbCallbackFunc: 24
08-09 08:45:16.030: I/native-activity(9166): my_obbCallbackFunc: 24
08-09 08:45:16.030: I/native-activity(9166): my_obbCallbackFunc: 24
08-09 08:45:16.030: I/native-activity(9166): my_obbCallbackFunc: 24
08-09 08:45:16.030: I/native-activity(9166): my_obbCallbackFunc: 24

根据android-ndk-r8d/platforms/android-9/arch-arm/usr/include/android/storage_manager.h，回调的错误代码意味着

AOBB_STATE_MOUNTED = 1,
AOBB_STATE_ERROR_ALREADY_MOUNTED = 24,

但是，这与AStorageManager_isObbMounted()调用的返回值中的logcat输出相矛盾，后者读取的是它尚未挂载。

我完全糊涂了。

Answer 1

我自己解决了。

挂载查询API肯定有一些违反直觉的地方，因为当我检查文件系统时，obb已经安装在/mnt/obb/下，但是API一直返回0，拒绝给我路径。它可能(细节语义在任何地方都没有记录)意味着这个 from请求未能获得安装的obb，尽管文件之前已经挂载过(回调中的错误代码24 )。

因此，如果我先卸载，然后再挂载在代码中，它应该是好的。因此，基本上添加如下：

AStorageManager_unmountObb(man, obbPath, 1, my_obbCallbackFunc, data);

在此之前

AStorageManager_mountObb(man, obbPath, "mykey", my_obbCallbackFunc, data);

通过回调：

void my_obbCallbackFunc(const char* filename, const int32_t state, void* data)
{
    LOGI("my_obbCallbackFunc: %d", state);

    AStorageManager* man = AStorageManager_new();
    int isMounted = AStorageManager_isObbMounted(man, filename);
    char* mntPath = AStorageManager_getMountedObbPath(man, filename);

    LOGI("my_obbCallbackFunc: fn: %s: mounted path: %s, already mounted?: %d", filename, mntPath, isMounted);
    AStorageManager_delete(man);
}

成功的产出：

08-09 10:41:53.060: I/native-activity(10753): File found: /sdcard/Android/obb/com.example.native_activity/main.1.com.example.native_activity.obb
08-09 10:41:53.070: E/Parcel(10753): Reading a NULL string not supported here.
08-09 10:41:53.070: I/native-activity(10753): mounted path: , already mounted?: 0
08-09 10:41:53.080: I/native-activity(10753): Touched screen.
08-09 10:41:53.080: I/native-activity(10753): File found: /sdcard/Android/obb/com.example.native_activity/main.1.com.example.native_activity.obb
08-09 10:41:53.110: I/native-activity(10753): my_obbCallbackFunc: 2
08-09 10:41:53.110: E/Parcel(10753): Reading a NULL string not supported here.
08-09 10:41:53.110: I/native-activity(10753): mounted path: , already mounted?: 0
08-09 10:41:53.110: E/Parcel(10753): Reading a NULL string not supported here.
08-09 10:41:53.110: I/native-activity(10753): my_obbCallbackFunc: fn: /storage/Android/obb/com.example.native_activity/main.1.com.example.native_activity.obb: mounted path: , already mounted?: 0
08-09 10:41:53.110: I/native-activity(10753): Touched screen.
08-09 10:41:53.110: I/native-activity(10753): File found: /sdcard/Android/obb/com.example.native_activity/main.1.com.example.native_activity.obb
08-09 10:41:53.110: E/Parcel(10753): Reading a NULL string not supported here.
08-09 10:41:53.110: I/native-activity(10753): mounted path: , already mounted?: 0
08-09 10:41:53.130: I/native-activity(10753): Touched screen.
08-09 10:41:53.130: I/native-activity(10753): File found: /sdcard/Android/obb/com.example.native_activity/main.1.com.example.native_activity.obb
08-09 10:41:53.130: E/Parcel(10753): Reading a NULL string not supported here.
08-09 10:41:53.130: I/native-activity(10753): mounted path: , already mounted?: 0
08-09 10:41:53.260: I/native-activity(10753): my_obbCallbackFunc: 1
08-09 10:41:53.300: I/native-activity(10753): my_obbCallbackFunc: 2
08-09 10:41:53.300: E/Parcel(10753): Reading a NULL string not supported here.
08-09 10:41:53.300: I/native-activity(10753): my_obbCallbackFunc: fn: /storage/Android/obb/com.example.native_activity/main.1.com.example.native_activity.obb: mounted path: , already mounted?: 1
08-09 10:41:53.300: E/Parcel(10753): Reading a NULL string not supported here.
08-09 10:41:53.300: I/native-activity(10753): my_obbCallbackFunc: fn: /storage/Android/obb/com.example.native_activity/main.1.com.example.native_activity.obb: mounted path: , already mounted?: 0
08-09 10:41:53.490: I/native-activity(10753): my_obbCallbackFunc: 1
08-09 10:41:53.520: I/native-activity(10753): my_obbCallbackFunc: 2
08-09 10:41:53.520: E/Parcel(10753): Reading a NULL string not supported here.
08-09 10:41:53.520: I/native-activity(10753): my_obbCallbackFunc: fn: /storage/Android/obb/com.example.native_activity/main.1.com.example.native_activity.obb: mounted path: , already mounted?: 0
08-09 10:41:53.520: E/Parcel(10753): Reading a NULL string not supported here.
08-09 10:41:53.520: I/native-activity(10753): my_obbCallbackFunc: fn: /storage/Android/obb/com.example.native_activity/main.1.com.example.native_activity.obb: mounted path: , already mounted?: 1
08-09 10:41:53.680: I/native-activity(10753): my_obbCallbackFunc: 1
08-09 10:41:53.720: I/native-activity(10753): my_obbCallbackFunc: 2
08-09 10:41:53.720: E/Parcel(10753): Reading a NULL string not supported here.
08-09 10:41:53.720: I/native-activity(10753): my_obbCallbackFunc: fn: /storage/Android/obb/com.example.native_activity/main.1.com.example.native_activity.obb: mounted path: , already mounted?: 1
08-09 10:41:53.720: E/Parcel(10753): Reading a NULL string not supported here.
08-09 10:41:53.720: I/native-activity(10753): my_obbCallbackFunc: fn: /storage/Android/obb/com.example.native_activity/main.1.com.example.native_activity.obb: mounted path: , already mounted?: 0
08-09 10:41:53.870: I/native-activity(10753): my_obbCallbackFunc: 1
08-09 10:41:53.880: I/native-activity(10753): my_obbCallbackFunc: fn: /storage/Android/obb/com.example.native_activity/main.1.com.example.native_activity.obb: mounted path: /mnt/obb/437f5d6d13a1da1d3b41bb46963e3720, already mounted?: 1

UPDATE：在使它完全工作之前，我还必须修复几个曲折：

1. 在使用jobb创建OBB时，除了正确命名文件外，-pv选项还必须与清单中的正确versionCode一起使用。
2. 每当需要对相同的OBB进行更新时，例如，OBB文件名中的versionCode保持不变，但内容已经改变，需要首先显式地删除设备上的OBB。否则，一个简单的亚行推动的OBB就不会奏效。您将继续在挂载回调中获得AOBB_STATE_ERROR_COULD_NOT_MOUNT (错误代码21)。这鼓励了版本化的使用，但使得在同一个OBB上进行临时测试很难，也就是说，不增加versionCode就不“建议”继续更改OBB。这意味着您需要首先删除OBB，以“覆盖”完全相同的OBB文件。
3. 许多教程的重点是教您如何使用下载库，以及如何对GooglePlay进行上载/下载舞蹈。如果您想要做的就是测试本地访问OBB，那是完全可以忽略的。