[path_provider] Android: Support multiple external storage options.

packages/path_provider/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.4.2
+
+* Support Android devices with multiple external storage options.
+
 ## 0.4.1
 
 * Updated Gradle tooling to match Android Studio 3.1.2.

packages/path_provider/android/src/main/java/io/flutter/plugins/pathprovider/PathProviderPlugin.java

@@ -4,15 +4,21 @@
 
 package io.flutter.plugins.pathprovider;
 
+import android.os.Build.VERSION;
+import android.os.Build.VERSION_CODES;
 import android.os.Environment;
 import io.flutter.plugin.common.MethodCall;
 import io.flutter.plugin.common.MethodChannel;
 import io.flutter.plugin.common.MethodChannel.MethodCallHandler;
 import io.flutter.plugin.common.MethodChannel.Result;
 import io.flutter.plugin.common.PluginRegistry.Registrar;
 import io.flutter.util.PathUtils;
+import java.io.File;
+import java.util.ArrayList;
+import java.util.List;
 
 public class PathProviderPlugin implements MethodCallHandler {
+
   private final Registrar mRegistrar;
 
   public static void registerWith(Registrar registrar) {
@@ -38,6 +44,13 @@ public void onMethodCall(MethodCall call, Result result) {
       case "getStorageDirectory":
         result.success(getPathProviderStorageDirectory());
         break;
+      case "getExternalCacheDirectories":
+        result.success(getPathProviderExternalCacheDirectories());
+        break;
+      case "getExternalStorageDirectories":
+        final String type = call.argument("type");
+        result.success(getPathProviderExternalStorageDirectories(type));
+        break;
       default:
         result.notImplemented();
     }
@@ -54,4 +67,42 @@ private String getPathProviderApplicationDocumentsDirectory() {
   private String getPathProviderStorageDirectory() {
     return Environment.getExternalStorageDirectory().getAbsolutePath();
   }
+
+  private List<String> getPathProviderExternalCacheDirectories() {
+    final List<String> paths = new ArrayList<>();
+
+    if (VERSION.SDK_INT >= VERSION_CODES.KITKAT) {
+      for (File dir : mRegistrar.context().getExternalCacheDirs()) {
+        if (dir != null) {
+          paths.add(dir.getAbsolutePath());
+        }
+      }
+    } else {
+      File dir = mRegistrar.context().getExternalCacheDir();
+      if (dir != null) {
+        paths.add(dir.getAbsolutePath());
+      }
+    }
+
+    return paths;
+  }
+
+  private List<String> getPathProviderExternalStorageDirectories(String type) {
+    final List<String> paths = new ArrayList<>();
+
+    if (VERSION.SDK_INT >= VERSION_CODES.KITKAT) {
+      for (File dir : mRegistrar.context().getExternalFilesDirs(type)) {
+        if (dir != null) {
+          paths.add(dir.getAbsolutePath());
+        }
+      }
+    } else {
+      File dir = mRegistrar.context().getExternalFilesDir(type);
+      if (dir != null) {
+        paths.add(dir.getAbsolutePath());
+      }
+    }
+
+    return paths;
+  }
 }

packages/path_provider/example/lib/main.dart

@@ -37,6 +37,8 @@ class _MyHomePageState extends State<MyHomePage> {
   Future<Directory> _tempDirectory;
   Future<Directory> _appDocumentsDirectory;
   Future<Directory> _externalDocumentsDirectory;
+  Future<List<Directory>> _externalStorageDirectories;
+  Future<List<Directory>> _externalCacheDirectories;
 
   void _requestTempDirectory() {
     setState(() {
@@ -59,6 +61,23 @@ class _MyHomePageState extends State<MyHomePage> {
     return Padding(padding: const EdgeInsets.all(16.0), child: text);
   }
 
+  Widget _buildDirectories(
+      BuildContext context, AsyncSnapshot<List<Directory>> snapshot) {
+    Text text = const Text('');
+    if (snapshot.connectionState == ConnectionState.done) {
+      if (snapshot.hasError) {
+        text = Text('Error: ${snapshot.error}');
+      } else if (snapshot.hasData) {
+        final String combined =
+            snapshot.data.map((Directory d) => d.path).join(', ');
+        text = Text('paths: $combined');
+      } else {
+        text = const Text('path unavailable');
+      }
+    }
+    return Padding(padding: const EdgeInsets.all(16.0), child: text);
+  }
+
   void _requestAppDocumentsDirectory() {
     setState(() {
       _appDocumentsDirectory = getApplicationDocumentsDirectory();
@@ -71,13 +90,25 @@ class _MyHomePageState extends State<MyHomePage> {
     });
   }
 
+  void _requestExternalStorageDirectories(String type) {
+    setState(() {
+      _externalStorageDirectories = getExternalStorageDirectories(type);
+    });
+  }
+
+  void _requestExternalCacheDirectories() {
+    setState(() {
+      _externalCacheDirectories = getExternalCacheDirectories();
+    });
+  }
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(
       appBar: AppBar(
         title: Text(widget.title),
       ),
-      body: Center(
+      body: SingleChildScrollView(
         child: Column(
           mainAxisAlignment: MainAxisAlignment.spaceEvenly,
           children: <Widget>[
@@ -92,10 +123,8 @@ class _MyHomePageState extends State<MyHomePage> {
                 ),
               ],
             ),
-            Expanded(
-              child: FutureBuilder<Directory>(
-                  future: _tempDirectory, builder: _buildDirectory),
-            ),
+            FutureBuilder<Directory>(
+                future: _tempDirectory, builder: _buildDirectory),
             Column(
               children: <Widget>[
                 Padding(
@@ -107,10 +136,8 @@ class _MyHomePageState extends State<MyHomePage> {
                 ),
               ],
             ),
-            Expanded(
-              child: FutureBuilder<Directory>(
-                  future: _appDocumentsDirectory, builder: _buildDirectory),
-            ),
+            FutureBuilder<Directory>(
+                future: _appDocumentsDirectory, builder: _buildDirectory),
             Column(children: <Widget>[
               Padding(
                 padding: const EdgeInsets.all(16.0),
@@ -122,11 +149,36 @@ class _MyHomePageState extends State<MyHomePage> {
                 ),
               ),
             ]),
-            Expanded(
-              child: FutureBuilder<Directory>(
-                  future: _externalDocumentsDirectory,
-                  builder: _buildDirectory),
-            ),
+            FutureBuilder<Directory>(
+                future: _externalDocumentsDirectory, builder: _buildDirectory),
+            Column(children: <Widget>[
+              Padding(
+                padding: const EdgeInsets.all(16.0),
+                child: RaisedButton(
+                  child: Text(
+                      '${Platform.isIOS ? "External directories are unavailable " "on iOS" : "Get External Storage Directories"}'),
+                  onPressed: Platform.isIOS
+                      ? null
+                      : () => _requestExternalStorageDirectories(null),
+                ),
+              ),
+            ]),
+            FutureBuilder<List<Directory>>(
+                future: _externalStorageDirectories,
+                builder: _buildDirectories),
+            Column(children: <Widget>[
+              Padding(
+                padding: const EdgeInsets.all(16.0),
+                child: RaisedButton(
+                  child: Text(
+                      '${Platform.isIOS ? "External directories are unavailable " "on iOS" : "Get External Cache Directories"}'),
+                  onPressed:
+                      Platform.isIOS ? null : _requestExternalCacheDirectories,
+                ),
+              ),
+            ]),
+            FutureBuilder<List<Directory>>(
+                future: _externalCacheDirectories, builder: _buildDirectories),
           ],
         ),
       ),

packages/path_provider/lib/path_provider.dart

@@ -61,3 +61,51 @@ Future<Directory> getExternalStorageDirectory() async {
   }
   return Directory(path);
 }
+
+/// Paths to directories where application specific cache data can be stored.
+/// These paths typically reside on external storage like separate partitions
+/// or SD cards. Phones may have multiple storage directories available.
+///
+/// The current operating system should be determined before issuing this
+/// function call, as this functionality is only available on Android.
+///
+/// On iOS, this function throws an UnsupportedError as it is not possible
+/// to access outside the app's sandbox.
+///
+/// On Android this returns Context.getExternalCacheDirs() or
+/// Context.getExternalCacheDir() on API levels below 19.
+Future<List<Directory>> getExternalCacheDirectories() async {
+  if (Platform.isIOS)
+    throw UnsupportedError("Functionality not available on iOS");
+  final List<dynamic> paths =
+      await _channel.invokeMethod('getExternalCacheDirectories');
+
+  return paths.map((dynamic path) => Directory(path)).toList();
+}
+
+/// Paths to directories where application specific data can be stored.
+/// These paths typically reside on external storage like separate partitions
+/// or SD cards. Phones may have multiple storage directories available.
+///
+/// The current operating system should be determined before issuing this
+/// function call, as this functionality is only available on Android.
+///
+/// On iOS, this function throws an UnsupportedError as it is not possible
+/// to access outside the app's sandbox.
+///
+/// The parameter type is optional. If it is set, it must be one of the
+/// "DIRECTORY" constants defined in `android.os.Environment`, e.g.
+/// https://developer.android.com/reference/android/os/Environment#DIRECTORY_MUSIC
+///
+/// On Android this returns Context.getExternalFilesDirs(String type) or
+/// Context.getExternalFilesDir(String type) on API levels below 19.
+Future<List<Directory>> getExternalStorageDirectories(String type) async {
+  if (Platform.isIOS)
+    throw UnsupportedError("Functionality not available on iOS");
+  final List<dynamic> paths = await _channel.invokeMethod(
+    'getExternalStorageDirectories',
+    <String, String>{"type": type},
+  );
+
+  return paths.map((dynamic path) => Directory(path)).toList();
+}

packages/path_provider/pubspec.yaml

@@ -3,7 +3,7 @@ description: Flutter plugin for getting commonly used locations on the Android &
   iOS file systems, such as the temp and app data directories.
 author: Flutter Team <[email protected]>
 homepage: https://github.com/flutter/plugins/tree/master/packages/path_provider
-version: 0.4.1
+version: 0.4.2
 
 flutter:
   plugin: