如何写入 android 的内部存储

Question

我正在使用 qtcreator 并通过我的 IDE 创建了一个 AndroidManifest.xml，它具有 WRITE_EXTERNAL_STORAGE 权限，但我无法写入任何文件进入我的移动 phone 存储（/storage/self/primary 或 /storage/emulated/0/）（错误：文件未打开）

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<?xml version="1.0"?>
<manifest package="org.qtproject.example" xmlns:android="http://schemas.android.com/apk/res/android" android:versionName="-- %%INSERT_VERSION_NAME%% --" android:versionCode="-- %%INSERT_VERSION_CODE%% --" android:installLocation="auto">
        <uses-sdk android:minSdkVersion="16" android:targetSdkVersion="29"/>

        <!-- The following comment will be replaced upon deployment with default permissions based on the dependencies of the application.
                 Remove the comment if you do not require these default permissions. -->
        <!-- %%INSERT_PERMISSIONS -->

        <!-- The following comment will be replaced upon deployment with default features based on the dependencies of the application.
                 Remove the comment if you do not require these default features. -->
        <!-- %%INSERT_FEATURES -->

        <supports-screens android:largeScreens="true" android:normalScreens="true" android:anyDensity="true" android:smallScreens="true"/>

        <application android:hardwareAccelerated="true" android:name="org.qtproject.qt5.android.bindings.QtApplication" android:label="-- %%INSERT_APP_NAME%% --">
        <activity android:configChanges="orientation|uiMode|screenLayout|screenSize|smallestScreenSize|layoutDirection|locale|fontScale|keyboard|keyboardHidden|navigation|mcc|mnc|density" android:name="org.qtproject.qt5.android.bindings.QtActivity" android:label="-- %%INSERT_APP_NAME%% --" android:screenOrientation="landscape" android:launchMode="singleTop">
            <intent-filter>
                                <action android:name="android.intent.action.MAIN"/>
                                <category android:name="android.intent.category.LAUNCHER"/>
                        </intent-filter>
            <!-- Application arguments -->
            <!-- meta-data android:name="android.app.arguments" android:value="arg1 arg2 arg3"/ -->
            <!-- Application arguments -->
            <meta-data android:name="android.app.lib_name" android:value="-- %%INSERT_APP_LIB_NAME%% --"/>
            <meta-data android:name="android.app.qt_sources_resource_id" android:resource="@array/qt_sources"/>
            <meta-data android:name="android.app.repository" android:value="default"/>
            <meta-data android:name="android.app.qt_libs_resource_id" android:resource="@array/qt_libs"/>
            <meta-data android:name="android.app.bundled_libs_resource_id" android:resource="@array/bundled_libs"/>
            <!-- Deploy Qt libs as part of package -->
            <meta-data android:name="android.app.bundle_local_qt_libs" android:value="-- %%BUNDLE_LOCAL_QT_LIBS%% --"/>
            <meta-data android:name="android.app.bundled_in_lib_resource_id" android:resource="@array/bundled_in_lib"/>
            <meta-data android:name="android.app.bundled_in_assets_resource_id" android:resource="@array/bundled_in_assets"/>
            <!-- Run with local libs -->
            <meta-data android:name="android.app.use_local_qt_libs" android:value="-- %%USE_LOCAL_QT_LIBS%% --"/>
            <meta-data android:name="android.app.libs_prefix" android:value="/data/local/tmp/qt/"/>
            <meta-data android:name="android.app.load_local_libs" android:value="-- %%INSERT_LOCAL_LIBS%% --"/>
            <meta-data android:name="android.app.load_local_jars" android:value="-- %%INSERT_LOCAL_JARS%% --"/>
            <meta-data android:name="android.app.static_init_classes" android:value="-- %%INSERT_INIT_CLASSES%% --"/>
            <!-- Used to specify custom system library path to run with local system libs -->
            <!-- <meta-data android:name="android.app.system_libs_prefix" android:value="/system/lib/"/> -->
            <!--  Messages maps -->
            <meta-data android:value="@string/ministro_not_found_msg" android:name="android.app.ministro_not_found_msg"/>
            <meta-data android:value="@string/ministro_needed_msg" android:name="android.app.ministro_needed_msg"/>
            <meta-data android:value="@string/fatal_error_msg" android:name="android.app.fatal_error_msg"/>
            <meta-data android:value="@string/unsupported_android_version" android:name="android.app.unsupported_android_version"/>
            <!--  Messages maps -->
            <!-- Splash screen -->
            <!-- Orientation-specific (portrait/landscape) data is checked first. If not available for current orientation,
                                 then android.app.splash_screen_drawable. For best results, use together with splash_screen_sticky and
                                 use hideSplashScreen() with a fade-out animation from Qt Android Extras to hide the splash screen when you
                                 are done populating your window with content. -->
            <!-- meta-data android:name="android.app.splash_screen_drawable_portrait" android:resource="@drawable/logo_portrait" / -->
            <!-- meta-data android:name="android.app.splash_screen_drawable_landscape" android:resource="@drawable/logo_landscape" / -->
            <!-- meta-data android:name="android.app.splash_screen_drawable" android:resource="@drawable/logo"/ -->
            <!-- meta-data android:name="android.app.splash_screen_sticky" android:value="true"/ -->
            <!-- Splash screen -->
            <!-- Background running -->
            <!-- Warning: changing this value to true may cause unexpected crashes if the
                                                    application still try to draw after
                                                    "applicationStateChanged(Qt::ApplicationSuspended)"
                                                    signal is sent! -->
            <meta-data android:name="android.app.background_running" android:value="false"/>
            <!-- Background running -->
            <!-- auto screen scale factor -->
            <meta-data android:name="android.app.auto_screen_scale_factor" android:value="false"/>
            <!-- auto screen scale factor -->
            <!-- extract android style -->
            <!-- available android:values :
                                * default - In most cases this will be the same as "full", but it can also be something else if needed, e.g., for compatibility reasons
                                * full - useful QWidget & Quick Controls 1 apps
                                * minimal - useful for Quick Controls 2 apps, it is much faster than "full"
                                * none - useful for apps that don't use any of the above Qt modules
                                -->
            <meta-data android:name="android.app.extract_android_style" android:value="minimal"/>
            <!-- extract android style -->
        </activity>
        <!-- For adding service(s) please check: https://wiki.qt.io/AndroidServices -->
    </application>

    <uses-permission android:name="android.permission.CAMERA"/>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>


</manifest>

Answer 1

由于您可能具有写入存储的功能，您很可能没有在运行时检查存储权限，正如@Ak23 指出的那样。以下是您如何进行检查和授予权限的示例代码：

bool uploadToStorage()
{
    auto result = QtAndroid::checkPermission(QString("android.permission.WRITE_EXTERNAL_STORAGE"));

    if (result == QtAndroid::PermissionResult::Denied) {
        QtAndroid::PermissionResultMap resultHash = QtAndroid::requestPermissionsSync(QStringList({"android.permission.WRITE_EXTERNAL_STORAGE"}));

        if (resultHash["android.permission.WRITE_EXTERNAL_STORAGE"] == QtAndroid::PermissionResult::Denied)
            return false;

        else {
            /* Here is Your method to upload to storage */

            return true;
        }
    }

    else {
        /* Here is Your method to upload to storage */

        return true;
    }
}

如您所见 - 首先您使用 checkPermission() 检查权限是否被授予，接下来如果没有被授予您必须使用requestPermissionsSync() - 如果您想授予写入存储的权限，它应该会显示一个带有问题的弹出窗口。确保权限OK后，就可以调用上传文件的函数了。

如何写入 android 的内部存储

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