Use document provider (by intent) APIs for import/export of settings to/from a file; fixes #543

app/src/main/java/org/transdroid/core/app/settings/SettingsPersistence.java

@@ -16,11 +16,9 @@
  */
 package org.transdroid.core.app.settings;
 
-import java.io.File;
-import java.io.FileInputStream;
-import java.io.FileNotFoundException;
-import java.io.FileWriter;
-import java.io.IOException;
+import android.content.SharedPreferences;
+import android.content.SharedPreferences.Editor;
+import android.os.Environment;
 
 import org.androidannotations.annotations.Bean;
 import org.androidannotations.annotations.EBean;
@@ -30,9 +28,13 @@ import org.json.JSONException;
 import org.json.JSONObject;
 import org.transdroid.daemon.util.HttpHelper;
 
-import android.content.SharedPreferences;
-import android.content.SharedPreferences.Editor;
-import android.os.Environment;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
 
 /**
  * Singleton class that can persist user settings (servers, RSS feeds, etc.) to and from a plain text JSON file.
@@ -48,8 +50,8 @@ public class SettingsPersistence {
 	protected SystemSettings systemSettings;
 
 	public static final String DEFAULT_SETTINGS_DIR = Environment.getExternalStorageDirectory().toString()
-			+ "/Transdroid";
-	public static final String DEFAULT_SETTINGS_FILENAME = "/settings.json";
+			+ "/Transdroid/";
+	public static final String DEFAULT_SETTINGS_FILENAME = "settings.json";
 	public static final File DEFAULT_SETTINGS_FILE = new File(DEFAULT_SETTINGS_DIR + DEFAULT_SETTINGS_FILENAME);
 
 	/**
@@ -59,9 +61,7 @@ public class SettingsPersistence {
 	 * @throws JSONException Thrown when the file did not contain valid JSON content
 	 */
 	public void importSettingsAsString(SharedPreferences prefs, String contents) throws JSONException {
-
 		importSettings(prefs, new JSONObject(contents));
-
 	}
 
 	/**
@@ -72,12 +72,20 @@ public class SettingsPersistence {
 	 * @throws FileNotFoundException Thrown when the settings file doesn't exist or couldn't be read
 	 * @throws JSONException Thrown when the file did not contain valid JSON content
 	 */
-	public void importSettingsFromFile(SharedPreferences prefs, File settingsFile) throws FileNotFoundException,
-			JSONException {
+	public void importSettingsFromFile(SharedPreferences prefs, File settingsFile) throws FileNotFoundException, JSONException {
+        importSettingsFromStream(prefs, new FileInputStream(settingsFile));
+	}
 
-		String raw = HttpHelper.convertStreamToString(new FileInputStream(settingsFile));
+    /**
+     * Synchronously reads the server, web searches, RSS feed, background service and system settings from a stream (file) in
+     * JSON format.
+     * @param prefs The application-global preferences object to write settings to
+     * @param settingsStream The stream to read the settings from
+     * @throws JSONException Thrown when the file did not contain valid JSON content
+     */
+    public void importSettingsFromStream(SharedPreferences prefs, InputStream settingsStream) throws JSONException {
+        String raw = HttpHelper.convertStreamToString(settingsStream);
         importSettings(prefs, new JSONObject(raw));
-
     }
 
 	public void importSettings(SharedPreferences prefs, JSONObject json) throws JSONException {
@@ -237,20 +245,30 @@ public class SettingsPersistence {
 	 * @throws IOException Thrown when the settings file could not be created or written to
 	 */
 	public void exportSettingsToFile(SharedPreferences prefs, File settingsFile) throws JSONException, IOException {
-
-		JSONObject json = exportSettings(prefs);
-		
-		// Serialise the JSON object to a file
 		if (settingsFile.exists()) {
 			settingsFile.delete();
 		}
 		settingsFile.getParentFile().mkdirs();
 		settingsFile.createNewFile();
-		FileWriter writer = new FileWriter(settingsFile);
-		writer.write(json.toString(2));
-		writer.flush();
-		writer.close();
+		exportSettingsToStream(prefs, new FileOutputStream(settingsFile));
+	}
 
+	/**
+	 * Synchronously writes the server, web searches, RSS feed, background service and system settings to a stream (file) in JSON format. The stream
+	 * will be closed regardless of success.
+	 *
+	 * @param prefs          The application-global preferences object to read settings from
+	 * @param settingsStream The stream to read the settings to
+	 * @throws JSONException Thrown when the JSON content could not be constructed properly
+	 * @throws IOException   Thrown when the settings file could not be created or written to
+	 */
+	public void exportSettingsToStream(SharedPreferences prefs, OutputStream settingsStream) throws JSONException, IOException {
+		try {
+			JSONObject json = exportSettings(prefs);
+			settingsStream.write(json.toString(2).getBytes());
+		} finally {
+			settingsStream.close();
+		}
 	}
 
 	private JSONObject exportSettings(SharedPreferences prefs) throws JSONException {

app/src/main/java/org/transdroid/core/gui/settings/SystemSettingsActivity.java

@@ -50,6 +50,8 @@ import org.transdroid.core.service.AppUpdateJob;
 
 import java.io.FileNotFoundException;
 import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
 
 @EActivity
 public class SystemSettingsActivity extends PreferenceCompatActivity {
@@ -72,6 +74,9 @@ public class SystemSettingsActivity extends PreferenceCompatActivity {
 			return true;
 		}
 	};
+	protected static final int ACTIVITY_IMPORT_SETTINGS = 1;
+	protected static final int ACTIVITY_EXPORT_SETTINGS = 2;
+
 	@Bean
 	protected NavigationHelper navigationHelper;
 	@Bean
@@ -99,7 +104,8 @@ public class SystemSettingsActivity extends PreferenceCompatActivity {
 	private OnClickListener importSettingsFromFile = new OnClickListener() {
 		@Override
 		public void onClick(DialogInterface dialog, int which) {
-			if (!navigationHelper.checkSettingsReadPermission(SystemSettingsActivity.this))
+			if (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT
+					&& !navigationHelper.checkSettingsReadPermission(SystemSettingsActivity.this))
 				return; // We are requesting permission to access file storage
 			importSettingsFromFile();
 		}
@@ -114,7 +120,8 @@ public class SystemSettingsActivity extends PreferenceCompatActivity {
 	private OnClickListener exportSettingsToFile = new OnClickListener() {
 		@Override
 		public void onClick(DialogInterface dialog, int which) {
-			if (!navigationHelper.checkSettingsWritePermission(SystemSettingsActivity.this))
+			if (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT
+					&& !navigationHelper.checkSettingsWritePermission(SystemSettingsActivity.this))
 				return; // We are requesting permission to access file storage
 			exportSettingsToFile();
 		}
@@ -171,10 +178,17 @@ public class SystemSettingsActivity extends PreferenceCompatActivity {
 	}
 
 	private void importSettingsFromFile() {
-		SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(SystemSettingsActivity.this);
 		try {
+			if (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT) {
+				SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(SystemSettingsActivity.this);
 				settingsPersistence.importSettingsFromFile(prefs, SettingsPersistence.DEFAULT_SETTINGS_FILE);
 				SnackbarManager.show(Snackbar.with(SystemSettingsActivity.this).text(R.string.pref_import_success));
+			} else {
+				Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
+				intent.addCategory(Intent.CATEGORY_OPENABLE);
+				intent.setType("application/json");
+				startActivityForResult(intent, ACTIVITY_IMPORT_SETTINGS);
+			}
 		} catch (FileNotFoundException e) {
 			SnackbarManager
 					.show(Snackbar.with(SystemSettingsActivity.this).text(R.string.error_file_not_found).colorResource(R.color.red));
@@ -184,17 +198,59 @@ public class SystemSettingsActivity extends PreferenceCompatActivity {
 		}
 	}
 
-	private void exportSettingsToFile() {
+	@OnActivityResult(ACTIVITY_IMPORT_SETTINGS)
+	public void importSettingsFilePicked(int resultCode, Intent data) {
+		if (resultCode == RESULT_OK && data != null && data.getData() != null) {
+			try {
+				InputStream fis = getContentResolver().openInputStream(data.getData());
+				if (fis != null) {
 					SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(SystemSettingsActivity.this);
+					settingsPersistence.importSettingsFromStream(prefs, fis);
+					SnackbarManager.show(Snackbar.with(SystemSettingsActivity.this).text(R.string.pref_import_success));
+				}
+			} catch (IOException | JSONException e) {
+				SnackbarManager.show(Snackbar.with(SystemSettingsActivity.this).text(R.string.error_file_not_found)
+						.colorResource(R.color.red));
+			}
+		}
+	}
+
+	private void exportSettingsToFile() {
 		try {
+			if (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT) {
+				SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(SystemSettingsActivity.this);
 				settingsPersistence.exportSettingsToFile(prefs, SettingsPersistence.DEFAULT_SETTINGS_FILE);
 				SnackbarManager.show(Snackbar.with(SystemSettingsActivity.this).text(R.string.pref_export_success));
+			} else {
+				Intent intent = new Intent(Intent.ACTION_CREATE_DOCUMENT);
+				intent.addCategory(Intent.CATEGORY_OPENABLE);
+				intent.setType("application/json");
+				intent.putExtra(Intent.EXTRA_TITLE, SettingsPersistence.DEFAULT_SETTINGS_FILENAME);
+				startActivityForResult(intent, ACTIVITY_EXPORT_SETTINGS);
+			}
 		} catch (JSONException | IOException e) {
 			SnackbarManager.show(Snackbar.with(SystemSettingsActivity.this).text(R.string.error_cant_write_settings_file)
 					.colorResource(R.color.red));
 		}
 	}
 
+	@OnActivityResult(ACTIVITY_EXPORT_SETTINGS)
+	public void exportSettingsFilePicked(int resultCode, Intent data) {
+		if (resultCode == RESULT_OK && data != null && data.getData() != null) {
+			try {
+				OutputStream fos = getContentResolver().openOutputStream(data.getData());
+				if (fos != null) {
+					SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(SystemSettingsActivity.this);
+					settingsPersistence.exportSettingsToStream(prefs, fos);
+					SnackbarManager.show(Snackbar.with(SystemSettingsActivity.this).text(R.string.pref_export_success));
+				}
+			} catch (IOException | JSONException e) {
+				SnackbarManager.show(Snackbar.with(SystemSettingsActivity.this).text(R.string.error_cant_write_settings_file)
+						.colorResource(R.color.red));
+			}
+		}
+	}
+
 	@OnActivityResult(BarcodeHelper.ACTIVITY_BARCODE_QRSETTINGS)
 	public void onQrCodeScanned(@SuppressWarnings("UnusedParameters") int resultCode, Intent data) {
 		// We should have received Intent extras with the QR-decoded data representing Transdroid settings
@@ -222,7 +278,8 @@ public class SystemSettingsActivity extends PreferenceCompatActivity {
 				return new AlertDialog.Builder(this)
 						.setMessage(
 								getString(
-									R.string.pref_import_dialog,
+										Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT
+												? R.string.pref_import_dialog : R.string.pref_import_dialog_android10,
 										getString(R.string.app_name),
 										SettingsPersistence.DEFAULT_SETTINGS_FILE.toString()))
 						.setPositiveButton(R.string.pref_import_fromfile, importSettingsFromFile)
@@ -234,7 +291,8 @@ public class SystemSettingsActivity extends PreferenceCompatActivity {
 			return new AlertDialog.Builder(this)
 					.setMessage(
 							getString(
-									R.string.pref_export_dialog,
+									Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT
+											? R.string.pref_export_dialog : R.string.pref_export_dialog_android10,
 									getString(R.string.app_name),
 									SettingsPersistence.DEFAULT_SETTINGS_FILE.toString()))
 					.setPositiveButton(R.string.pref_export_tofile, exportSettingsToFile)

app/src/main/res/values/changelog.xml

@@ -19,6 +19,7 @@
 <string name="system_changelog">
 Transdroid 2.5.18\n
 - BitComet details fixes\n
+- Settings import/export on Android 10+\n
 \n
 Transdroid 2.5.17\n
 - qBittorrent 4.2+ support\n

app/src/main/res/values/strings.xml

@@ -356,11 +356,13 @@
     <string name="pref_clearsearch_success">Search history is cleared</string>
     <string name="pref_import">Import settings</string>
     <string name="pref_import_dialog">%1$s will try to import server, web search, RSS and system settings from: %2$s</string>
+    <string name="pref_import_dialog_android10">%1$s will try to import server, web search, RSS and system settings</string>
     <string name="pref_import_fromfile">Use file</string>
     <string name="pref_import_fromqr">Use QR code</string>
     <string name="pref_import_success">Settings successfully imported</string>
     <string name="pref_export">Export settings</string>
     <string name="pref_export_dialog">%1$s will export server (including passwords), web search, RSS and system settings to the following plain text JSON file: %2$s</string>
+    <string name="pref_export_dialog_android10">%1$s will export server (including passwords), web search, RSS and system settings</string>
     <string name="pref_export_tofile">To file</string>
     <string name="pref_export_toqr">To QR code</string>
     <string name="pref_export_success">Settings successfully exported</string>