android - 无法使用 FileProvider 在 Android N 中打开外部存储文件

Question

我在使用 Android N 打开外部存储中的文件时遇到问题。

文件路径

file:///storage/emulated/0/Download/SamplePDFFile_5mb.pdf

初步实现完美兼容Android 7以下版本

File file = new File (Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS), "SamplePDFFile_5mb.pdf");
Uri uri = Uri.fromFile(file);
Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setDataAndType(uri, "application/pdf");
startActivity(intent);

相同的实现在 7 上不起作用，但有以下异常(exception)。

android.os.FileUriExposedException

所以我发现了类似的问题并关注this为了修复针对 24 或更高版本的应用程序的新 Android 安全功能。

新实现

File file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS), "SamplePDFFile_5mb.pdf");
//old way
//Uri uri = Uri.fromFile(file);
//new way
Uri uri = FileProvider.getUriForFile(MainActivity.this, getPackageName() + ".provider", file);

Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setDataAndType(uri, "application/pdf");
intent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
startActivity(intent);

provider_paths.xml

<paths xmlns:android="http://schemas.android.com/apk/res/android">
    <external-path name="external_files" path="."/>
</paths>

AndroidManifest.xml

<provider
    android:name="android.support.v4.content.FileProvider"
    android:authorities="${applicationId}.provider"
    android:exported="false"
    android:grantUriPermissions="true">
    <meta-data
        android:name="android.support.FILE_PROVIDER_PATHS"
        android:resource="@xml/provider_paths"/>
</provider>

即使在 Android Manifest、provider_paths.xml 和 FileProvider 中添加所需标签后，我也无法打开该文件。打开 Activity 自行关闭。logcat 中没有错误或消息。

Answer 1

public void getGROUPSTORAGEPremission(){
    int hasWriteContactsPermission = Splash_activity.this.checkSelfPermission(Manifest.permission_group.STORAGE);
    if (hasWriteContactsPermission != PackageManager.PERMISSION_GRANTED) {
        Splash_activity.this.requestPermissions(new String[]{  Manifest.permission_group.STORAGE},
                PERMISSION_GROUPSTORAGE);
    } else {
       File file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS), "SamplePDFFile_5mb.pdf");
     //old way
     //Uri uri = Uri.fromFile(file);
     //new way
     Uri uri = FileProvider.getUriForFile(MainActivity.this, getPackageName() + ".provider", file);

       Intent intent = new Intent(Intent.ACTION_VIEW);
       intent.setDataAndType(uri, "application/pdf");
       intent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
       startActivity(intent);
    }

}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults);
    if (requestCode == PERMISSION_GROUPSTORAGE) {
        if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
            // Permission Granted
            File file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS), "SamplePDFFile_5mb.pdf");
     //old way
     //Uri uri = Uri.fromFile(file);
     //new way
      Uri uri = FileProvider.getUriForFile(MainActivity.this, getPackageName() + ".provider", file);

       Intent intent = new Intent(Intent.ACTION_VIEW);
       intent.setDataAndType(uri, "application/pdf");
       intent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
       startActivity(intent);
        } else {
            // Permission Denied
            //Toast.makeText(mContext, "PERMISSION_GROUPSTORAGE Denied", Toast.LENGTH_SHORT).show();
        }
    }
 }

N后需要检查运行时权限。