private fun openFile(file: File) {
    try {
        val uri = FileProvider.getUriForFile(
            this,
            "${packageName}.fileprovider",
            file
        )
        val mimeType = when (file.extension.lowercase()) {
            "xlsx" -> "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
            "xls" -> "application/vnd.ms-excel"
            "csv" -> "text/csv"
            else -> "*/*"
        }
        val intent = Intent(Intent.ACTION_VIEW).apply {
            setDataAndType(uri, mimeType)
            addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
        }
        if (intent.resolveActivity(packageManager) != null) {
            startActivity(intent)
        } else {
            // 没有可以打开的应用 → 尝试分享
            val shareIntent = Intent(Intent.ACTION_SEND).apply {
                type = mimeType
                putExtra(Intent.EXTRA_STREAM, uri)
                addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
            }
            startActivity(Intent.createChooser(shareIntent, "打开文件"))
        }
    } catch (e: Exception) {
        Log.e("BenchmarkActivity", "Failed to open file", e)
        Toast.makeText(this, "无法打开文件: ${e.message}", Toast.LENGTH_LONG).show()
    }
}

<provider
    android:name="androidx.core.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>