android- FileProvider崩溃 - NPE试图调用一个空字符串XmlResourceParser(FileProvider crash - npe attempting to invoke XmlResourceParser on a null String)

问题：

This is a part of my manifest:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.asd"
android:versionCode="118"
android:versionName="118" >

<uses-sdk
android:minSdkVersion="14"
android:targetSdkVersion="19" />

<application
android:name="com.example.asd.AsdApplication"
android:allowBackup="true"
android:allowTaskReparenting="true"
android:theme="@style/AsdTheme" >
...

<provider
android:name="com.example.asd.database.hq.ContentProviderDB"
android:authorities="ourContentProviderAuthorities" >
</provider>
<provider
android:name="android.support.v4.content.FileProvider"
android:authorities="com.example.asd.fileprovider"
android:exported="false"
android:grantUriPermissions="true">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="@xml/filepaths" />
</provider>

...
</application>

</manifest>

This is the filepaths file in raw/xml/filepaths.xml

<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
<files-path name="media"/>
</paths>

I download a video from internet and save it to internal storage this way:

public static boolean saveInputStreamToInternalStorageFile(Context context, String filename, byte[] dataToWrite, Context ctx) {
FileOutputStream fos;
try {
fos = new FileOutputStream(context.getFilesDir() + File.separator + filename);

ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(dataToWrite);
oos.close();
return true;
} catch (FileNotFoundException e) {
e.printStackTrace();
return false;
} catch (IOException e) {
e.printStackTrace();
return false;
}
}

I try to use it like so:

private void playVideoFromDeviceWithWorkaround(String fileName) {

File newFile = new File(getFilesDir(), fileName);
Uri contentUri = FileProvider.getUriForFile(getApplicationContext(), "com.example.asd", newFile);

try {
vvVideoFullscreen.setVideoURI(contentUri);
showMediaControls = true;
playVideo();
} catch (Exception e) {
playVideoFromNetwork();
}

}

At this line:

Uri contentUri = FileProvider.getUriForFile(getApplicationContext(), "com.example.asd", newFile);

I get the following error:

java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.XmlResourceParser android.content.pm.ProviderInfo.loadXmlMetaData(android.content.pm.PackageManager, java.lang.String)' on a null object reference
at android.support.v4.content.FileProvider.parsePathStrategy(FileProvider.java:560)
at android.support.v4.content.FileProvider.getPathStrategy(FileProvider.java:534)
at android.support.v4.content.FileProvider.getUriForFile(FileProvider.java:376)

解决方案：

The problem was that in Manifest I had this line:

android:authorities="com.example.asd.fileprovider"

and when calling getUriForFile I was passing:

Uri contentUri = FileProvider.getUriForFile(getApplicationContext(), "com.example.asd", newFile);

So changed from "com.example.asd" to "com.example.asd.fileprovider" and it worked