我一直在尝试共享一个pdf文件，我这样设置FileProvider：
在主清单xml上：

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

res/xml/file_paths.xml档案：

<?xml version="1.0" encoding="utf-8"?>
<paths>
    <files-path name="my_files" path="." />
</paths>

在我的代码中，我尝试以下操作：

String path = root.getAbsolutePath() + "/file.pdf";
final Uri data = FileProvider.getUriForFile(getApplicationContext(), BuildConfig.APPLICATION_ID+".fileprovider", new File(path));
getApplicationContext().grantUriPermission(getApplicationContext().getPackageName(), data, Intent.FLAG_GRANT_READ_URI_PERMISSION);
final Intent intent = new Intent(Intent.ACTION_VIEW).setDataAndType(data, "application/pdf").addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
getApplicationContext().startActivity(intent);

返回错误：

Caused by: java.lang.IllegalArgumentException: Failed to find configured root that contains /storage/emulated/0/file.pdf