UnityWebRequest for local files on Android - failure

I use UnityWebRequest to load images over the internet. The non-block native texture handling works well and everything is quite smooth.

Another very handy feature of UnityWebRequest is that it can actually load from HDD too, using file:// instead of http. This is very handy for caching as all you really need to do is alter the load path prefix to switch from a remote url to a local file path.

Only problem is it doesn't seem to work on Android.

Anyone out there able to get local UntyWebRequest image loading happening from an Android phone?

 

I added a bug report a month or so ago here if anyone is interested:

https://fogbugz.unity3d.com/default.asp?843412_h9ibu4sm4bld11g3

 

I have a similar problem.
UnityWebRequest for local files doesn't work on even Windows since 5.4.3p3.
I tried again 5.4.4p2. but It doesn't solved.

 

I found a workaround by accident.
Use url prefix file:/// instead of file://.

 

In the Unity 5.6, the UnityWebRequest for local files uses again the format "file://". If you use 3 slashes, it does not work.

 

If the first character of the path (Application.persistentDataPath for example) is "/" then you need three slashes. FYI for anyone dealing with that issue.

 

We have never managed to get UnityWebRequest and a DownloadHandlerTexture to load files from StreamingAssets on Android, and don't understand why. This is with Unity 5.6.3f1, but we have tried many other 5.x versions. The same code has always worked fine with WWW, and runs on all platforms other than Android. Note for sanity, we have constructed the path string in two different ways, and checked that filePathPerDocs and filePathFromStreamingAssets are identical.

Code (csharp):

1.  
2.         // Construct path as recommended in https://docs.unity3d.com/Manual/StreamingAssets.html
3.         string filePathPerDocs = "jar:file://" + Application.dataPath + "!/assets/" + fileName;  
4.         Debug.Log("File Path per docs: " + filePathPerDocs);
5.  
6.         // Construct path as we always have for streaming assets.
7. string filePathFromStreamingAssets = Application.streamingAssetsPath + "/" + fileName;  
8.         if (Application.platform != RuntimePlatform.Android)
9.         {
10.             filePathFromStreamingAssets = "file://" + filePathFromStreamingAssets;
11.         }
12.         Debug.Log("File path using streamingassets: " + filePathFromStreamingAssets);
13.  
14.         // Load it. This will fail, but will work if using a WWW.
15. using (UnityWebRequest www = UnityWebRequest.GetTexture(filePathFromStreamingAssets))
16.  

On Android, both of these functions build a string of the form:

jar:file:///data/app/com.mycompany.application-nlg8YQn72iHpXna6k-FeqQ==/base.apk!/assets/imageToLoad.png

And fail with: "A URL Connection to a Java ARchive (JAR) file or an entry in a JAR file is not supported."

Can somebody tell me what is wrong with this string (e.g. by typing the correct form of the above string)? We have tried all manner of permutations of file://, ///, etc.

Interestingly, this thread implies that UnityWebRequest streamingassets support on Android was only added in 2017.1 (post #16)

https://forum.unity.com/threads/unitywebrequest-getassetbundle-from-streamingassets.430689/

Yet there are replies higher in this thread (e.g. #5) saying it works in 5.6. I see nothing in the 2017.1 release notes saying that android streamingassets support for UnityWebRequest was added in this version.

 

Thanks for clarifying. We'll upgrade after our current release cycle.

 

@Aurimas-Cernius

Could you please state better ways to handle file operations. Let's say there is audio file/ video file or png/jpg on a local drive. I find UnityWebRequest & it's variety of download handlers to load the concerned file and make it Unity friendly.

My target is iOS && Android.

I have scoured the internet for a solid solution to load any Unity type file from local drive to Unity at runtime, to find none.

Thank you

 

Thanks all you guys for this wonderful thread this helped me

 

@Aurimas-Cernius could you be more specific, please? for instance, how to load a Texture2D during runtime (and not in the editor) with unity 2018.3? what is currently the best way and what you are referring to?

bear in mind that you need texture dimension information from that texture/image itself.

this is not an answer since width/height are static here: https://answers.unity.com/questions/432655/loading-texture-file-from-pngjpg-file-on-disk.html

 

Maybe I am missing something, but how is this done for AudioClip?

 

@Aurimas-Cernius Can you be more specific for why the Texture2D.Apply is more efficient compared to
UnityWebRequestTexture.GetTexture?

I am trying to build a gallery of in-game screenshots and have tried numerous methods to retrieve the screenshots from disk. The user can take a screenshot, the script saves the file to disk. I want the thumbnail of the new screenshot to populate a gallery of the last 10 screenshots that the user can load.

Everything works, except that since this is in-game, the texture is not refreshed when written to the games folder. While working In the editor, AssetDatabase.Refresh() makes it work like I want, but I can't access that in a build.

Using the persistentDatapath and UnityWebRequest gives me the behavior that I want. However, I'm suspicious that the screenshots are now loaded in memory, even when the gallery is not displayed. The same would be true if I used the ScreencaptureAsTexture method. The manual recommends destroying the texture after it's been created. To me, that's the same as just accessing a texture using UnityWebRequest, so I don't see the point.

 

We're experiencing what appears to be this same issue.

Code (CSharp):

1.  
2. using (UnityWebRequest www = UnityWebRequest.Get(url)) {
3.     UnityWebRequestAsyncOperation asyncOp = www.SendWebRequest();
4.     while (asyncOp.isDone == false) {
5.         await Task.Delay(30);
6.     }
7.     if (www.isNetworkError || www.isHttpError) {
8.          Debug.LogWarning($"Network error whilst downloading [{url}] Error: [{www.error}]");
9.          return null;
10.     }
11. }
12.  

We have tested with a url as:

jar:file:///storage/emulated/0/Texture.png
file:///storage/emulated/0/Texture.png
/storage/emulated/0/Texture.png
storage/emulated/0/Texture.png

Every other combination we can think to try.

We consistently get HTTP/1.1 404 Not Found returned as the www.error

This could be a permissions issue, though we have external write permission. Or it could be an issue with the UnityWebRequest system. Or we could be missing something fundemental about Android file loading.

--

We understand that Application.dataPath and Application.persistentDataPath both exist (Though since neither path seems to be visible in a file explorer, we can't add our files there).

Our use case is that we need the access files that exist on our device outside the application folder. They will be placed there using a standard file explorer, ideally in a folder like "storage/CustomFolder/Texture.png".

There are lots of forum posts around this issue, but as is tradition, they all seem to go dead and remain unsolved.

 

The manifest in Android Studio includes

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

Various sources online state:
Note: If your app uses the WRITE_EXTERNAL_STORAGE permission, then it implicitly has permission to read the external storage as well.

Are you/ Is anyone aware of any other permissions or manifest keys that related to access?

It's worth nothing the the URI of the UnityWebRequest reads as http://localhost/storage/emulated/0, which I imagine is incorrect. Specifically using file:///storage/emulated/0 doesn't seem to make any difference (404).

Also noting I'm talking about primary internal storage, not an sd card, if that is likely to make a difference.

I remember doing this exact thing years ago through the old WWW class without half the headache

-

Any other pointers would be very appreciated.

 

So. The following is the code i'm using, roughly.

Code (CSharp):

1.  
2. Debug.Log($"({url}) File Exists: {File.Exists(url)} ");
3. using (UnityWebRequest www = UnityWebRequestTexture.GetTexture(url)) {
4.     UnityWebRequestAsyncOperation request = www.SendWebRequest();
5.     while (!request.isDone || !www.isDone) await Task.Delay(30);
6.     if (www.isNetworkError || www.isHttpError) {
7.         Debug.LogWarning($"WWW ({url}) has error: {www.error}");
8.         return null;
9.     }
10.     ...
11. }
12.  

Logs:

(/storage/emulated/0/myImage.jpg) File Exists: True
java.net.ConnectException: Failed to connect to localhost/127.0.0.1:80
WWW (/storage/emulated/0/myImage.jpg) has error: Unknown Error

-

I've also used File.ReadAllBytes, which reads correctly (Read 475849bytes).

So IO is quite happy to work with the file, but UnityWebRequest isn't?

I appriciate all the help - I know support with so many unknowns is a real pain, so thank you very much for your time.

 

I'm getting the following error on Android, I'm a beginner but I think this is related.

Spoiler: Logs

Instantiating Bundle- Preparing
UnityEngine.Logger:Log(LogType, Object)
<InstantiateBundle>d__8:MoveNext()
UnityEngine.SetupCoroutine:InvokeMoveNext(IEnumerator, IntPtr)
DownloaderFiles:SaveFile(Byte[])
<CdnDownloadFile>d__5:MoveNext()
UnityEngine.SetupCoroutine:InvokeMoveNext(IEnumerator, IntPtr)
(Filename: ./Runtime/Export/Debug.bindings.h Line: 45)
java.net.ConnectException: Connection refused
(Filename: Line: 451)
Bundle Get Content
UnityEngine.Logger:Log(LogType, Object)
<InstantiateBundle>d__8:MoveNext()
UnityEngine.SetupCoroutine:InvokeMoveNext(IEnumerator, IntPtr)
(Filename: ./Runtime/Export/Debug.bindings.h Line: 45)
InvalidOperationException: Unknown Error
at UnityEngine.Networking.DownloadHandler.GetCheckedDownloader[T] (UnityEngine.Networking.UnityWebRequest www) [0x00000] in <00000000000000000000000000000000>:0
at UnityEngine.Networking.DownloadHandlerAssetBundle.GetContent (UnityEngine.Networking.UnityWebRequest www) [0x00000] in <00000000000000000000000000000000>:0
at DownloaderBundles+<InstantiateBundle>d__8.MoveNext () [0x00000] in <00000000000000000000000000000000>:0
at UnityEngine.SetupCoroutine.InvokeMoveNext (System.Collections.IEnumerator enumerator, System.IntPtr returnValueAddress) [0x00000] in <00000000000000000000000000000000>:0
(Filename: currently not available on il2cpp Line: -1)

Code (CSharp):

1. Debug.Log("Instantiating Bundle- Preparing");
2.         UnityEngine.Networking.UnityWebRequest request =
3.             UnityEngine.Networking.UnityWebRequestAssetBundle.GetAssetBundle(savePath);
4.         yield return request.SendWebRequest();            
5.  
6.    
7.         Debug.Log("Bundle Get Content");
8.         AssetBundle bundle = DownloadHandlerAssetBundle.GetContent(request);
9.         Debug.Log("Bundle Load Asset");
10.         GameObject a = bundle.LoadAsset<GameObject>(assetToLoad);
11.  

 

Thankyou. We had tried every combination of file:// in the past with no luck. There must have been an issue with some other part of our code. The following code is working for us:

Code (CSharp):

1. public static async Task<(bool validURL, Texture thumbnail)> LoadImageThumbnail(string url) {
2.     url = url.Replace("$dataPath", Application.dataPath);
3.     url = url.Replace("$persistentDataPath", Application.persistentDataPath);
4.     url = url.Replace("$streamingAssetsPath", Application.streamingAssetsPath);
5.  
6.     string baseURL = url.Replace("file://", "");
7.     Debug.Log($"IO Exists: {File.Exists(baseURL)} ({baseURL})");
8.  
9.     using (UnityWebRequest www = UnityWebRequestTexture.GetTexture(url)) {
10.         UnityWebRequestAsyncOperation request = www.SendWebRequest();
11.         while (!request.isDone || !www.isDone) await Task.Delay(30);
12.         if (www.isNetworkError || www.isHttpError) {
13.             Debug.LogWarning($"WWW ({url}) has error: {www.error}");
14.             return (false, null);
15.         }
16.  
17.         Texture2D handledTexture = DownloadHandlerTexture.GetContent(www);
18.         if (handledTexture == null) {
19.             return (false, null);
20.         }
21.         Texture2D texture = new Texture2D(handledTexture.width, handledTexture.height, TextureFormat.ARGB32, false);
22.         texture.name = Path.GetFileNameWithoutExtension(url);
23.  
24.         texture.LoadImage(www.downloadHandler.data);
25.      
26.         texture.Apply();
27.  
28.         //return valid results:
29.         return (true, texture);
30.     }
31. }

An example path we're using:
file:///storage/emulated/0/Corridor.jpg

 

I have tried the followings Uris

/storage/emulated/0/Android/data/com.sri.sriedu/files/sriGames/mybundle
file:///storage/emulated/0/Android/data/com.sri.sriedu/files/sriGames/mybundle

I get the same error for both of the above ,
java.net.ConnectException: Connection refused

 

Can you please give the uri that worked for you. Also , in the player settings, what is the min / max target android api, that is working for you? And the Unity Version that is working for you?

 

I updated Unity and reinstalled Android Studio and sdk
Still getting the same error.
File.ReadAllBytes works ok. But UWR does not.

Unity Version is 2018.3.9f1

My Player Settings are as follows :
Minimum API Level 21
Target API Level 26
Scripting Runtime Version .NET 4.x equivalent
Scripting Backend IL2CPP
Api Compatibility Level : .NET Standard 2.0


Install Location : External
Internet Access : Require
Write Permission : Internal


Permissions as per the manifest are :

<uses-permission
android:name="android.permission.INTERNET" />

<uses-permission
android:name="com.android.vending.BILLING" />

<uses-permission
android:name="android.permission.ACCESS_NETWORK_STATE" />


Also , on inspecting the APK in Android Studio , in the manifest the following line has been flagged as an error :

xmlns:android="http://schemas.android.com/apk/res/android"
Error : URI Is not registered (Settings |Languages and Frameworks |Schemas and DTDs)



I'll file a bug report soon, unless any of the above already points to the problem ?
Thanks

 

Unity Version is 2018.3.9f1

 

Added an example URL - the URI is generated in the code, not directly set

Min: 6.0 (23)
Max: Auto (Highest)

2018.3.8f1

 

Thank you very much for the info.
I am also setting the URI from code , and it's the same format. But I'm trying access an Asset Bundle, so maybe something to do with that...

 

Hey,

My Unity version is 2019.1.4f1 and I had the same issues as described above (developing for Oculus Go, which uses an Android platform). I managed to fix it. The final code can be seen here (it is full of commented debug.logs for you to test):

Spoiler: Code

Code (CSharp):

1. IEnumerator LoadImageFromDisk(string id, string path, Action<string, string, Texture2D> callback)
2. {
3.     using (UnityWebRequest uwr = UnityWebRequestTexture.GetTexture(path))
4.     {
5.         // string baseURL = path.Replace("file://", "");
6.         // Debug.Log($"IO Exists: {File.Exists(path)} ({path})");
7.  
8.         // Debug.Log("uwr.uri: " + uwr.uri);
9.         // Debug.Log("uwr.uri.absoluteUri: " + uwr.uri.AbsoluteUri);
10.         // Debug.Log("uwr.uri.absolutePath: " + uwr.uri.AbsolutePath);
11.         // Debug.Log("uwr.url: " + uwr.url);
12.  
13.         uwr.uri = new Uri(uwr.uri.AbsoluteUri.Replace("http://localhost", "file://"));
14.         uwr.url = uwr.url.Replace("http://localhost", "file://");
15.  
16.         yield return uwr.SendWebRequest();
17.  
18.         // Debug.Log("AFTER URL: " + uwr.url);
19.         // Debug.Log("AFTER URI.AbsoluteUri: " + uwr.uri.AbsoluteUri);
20.         // Debug.Log("AFTER URI.AbsoluteUrl: " + uwr.uri.AbsolutePath);
21.  
22.         if (uwr.isNetworkError || uwr.isHttpError)
23.         {
24.             Debug.LogError(uwr.error);
25.         }
26.         else
27.         {
28.             Debug.Log("Loaded file from " + path.Replace("/", "\\"));
29.             var tex = DownloadHandlerTexture.GetContent(uwr);
30.             if (tex != null)
31.             {
32.                 callback?.Invoke(id, path, tex);
33.             }
34.         }
35.     }
36. }

The beginnings of url and uri.absoluteUri are automatically set to "http://localhost" when the UnityWebRequest object is created. Before calling uwr.SendWebRequest() you have to do one of following (or both):

1. Change the beginning of uwr.uri.AbsoluteUri (in my case "http://localhost/storage/...") from "http://localhost" to "file://" (in my case "file:///storage/...". Notice 3 slashes, not 2!). To do that you have to create a new Uri object on the uwr.

   uwr.uri = new Uri(uwr.uri.AbsoluteUri.Replace("http://localhost", "file://"));

   .
2. Or do the same with uwr.url:

   uwr.url = uwr.url.Replace("http://localhost", "file://");

   .

 

Thank you very much FROSTY, you just have just saved me and my project....
I ve got the same issues and i was stuck in it.
You r my savior . it is working now !

 

I got this error The type or namespace name 'Action<,,>' could not be found (are you missing a using directive or an assembly reference?)

 

Please paste the full working code

 

Thanks a lot it worked for me !!!!

 

For me, the solution found on the Internet worked - to bring the target file names to lowercase. my task looked like this (on android): transfer the file from the StreamingAssets directory (into apk) to the PersistentDataPath directory for reading/writing. here is the code:

Code (CSharp):

1. if (!File.Exists(Application.persistentDataPath + "/gamedata"))
2.         {
3.             string path = "";
4.             #if (UNITY_EDITOR || UNITY_STANDALONE_LINUX)          
5.                 path = "file://" + Application.streamingAssetsPath + "/gamedata";          
6.             #endif
7.             #if (UNITY_ANDROID && !UNITY_EDITOR && !UNITY_STANDALONE_LINUX)                                      
8.                 path = Application.streamingAssetsPath + "/gamedata";
9.             #endif
10.             UnityEngine.Networking.UnityWebRequest www = UnityEngine.Networking.UnityWebRequest.Get(path);
11.             www.SendWebRequest();
12.             while (!www.isDone) { }
13.             byte[] loadBytes = www.downloadHandler.data;
14.             System.IO.File.WriteAllBytes(Application.persistentDataPath + "/gamedata", loadBytes);
15.         }

I hope I helped someone)

 

F***ing UnityWebRequest

 

you must use WWW

 

I do not understand why was WWW deprecated if this UnityWebRequest des not even begin to replace it.

 

www.bytes - what can replace this in UnityWebRequest ?
Dont tell me downloadhandler.data because it does on WEB Req and not when you want to read some files or classes.dex from storage.
Show me the way master !

 

Code (CSharp):

1.             string urlScheme = "jar:file://";
2.             string apkPath = Application.dataPath;
3.             string separator = "!/";
4.             string entry = "classes3.dex";
5.             string url = urlScheme + apkPath + separator + entry;
6.  
7.             WWW www = new WWW(url);
8.             yield return www;
9.  
10.             if (www.bytes.Length > 0)
11.                 Debug.Log("Found");

Be Friend and change this code to UnityWebRequest so it can work

 

So, here's a surprise. Android is INCREDIBLY PICKY about jar:file:// path names. So picky, in fact, that a path like this will fail:

Code (CSharp):

1. jar:file:///some/path/to//file.json

but this will succeed:

Code (CSharp):

1. jar:file:///some/path/to/file.json

Make absolutely certain you don't end up with an extra slash anywhere. I spent two hours tracking this down tonight, and sure enough, this was the problem.

 

So I needed to migrate from Resources.Load to my own class because Resources.Load broke when loading for Android for my project (not good to use Resources.Load anyway so meh), so I store my files in the persistent data path on Android (gonna use asset bundles that are downloaded from a server).

With the file in persistent data path, I just drag a file in called 'TestAudioClipOGG'.

You build a Uri using UriBuilder like this (works for me Unity 2021,1, Android 6.0+ AND windows this works too) and pass the UriBuilder.Uri right into UnityWebRequest.

Code (CSharp):

1.  
2.  
3. public class ExternalResources {
4.  
5.     public static async Task<AudioClip> LoadAudioClipAsync(string relativePath)
6.     {
7.         string filePath = GetFileFullPath(relativePath, ".ogg");
8.         if (filePath == null)
9.             return null;
10.  
11.         UriBuilder uriBuilder = new UriBuilder(filePath);
12.  
13.         UnityEngine.Debug.Log("uriBuilder.uri: " + uriBuilder.Uri);
14.  
15.         using (UnityWebRequest unityWebRequest = UnityWebRequestMultimedia.GetAudioClip(uriBuilder.Uri, AudioType.OGGVORBIS))
16.         {
17.             unityWebRequest.SendWebRequest();
18.  
19.             while (unityWebRequest.isDone == false)
20.                 await Task.Delay(5);
21.  
22.             if (unityWebRequest.result == UnityWebRequest.Result.ConnectionError || unityWebRequest.result == UnityWebRequest.Result.DataProcessingError)
23.             {
24.                 UnityEngine.Debug.LogError("Data Processing or Connection Error for filePath: " + filePath);
25.                 return null;
26.             }
27.  
28.             return DownloadHandlerAudioClip.GetContent(unityWebRequest);
29.  
30.         }
31.  
32.     }
33.  
34.  
35.     private static string GetFileFullPath(string relativePath, string extension)
36.     {
37.         string fullPath = UnityDataPath + "/" + relativePath + extension;
38.         if (File.Exists(fullPath) == false)
39.         {
40.             UnityEngine.Debug.LogError("No asset found with path of: " + fullPath);
41.             return null;
42.         } else
43.         {
44.             return fullPath;
45.         }
46.  
47.     }
48.  
49. }
50.  
51.  

You run it like this:

Code (CSharp):

1. Task<AudioClip> acTask = ExternalResources.LoadAudioClipAsync("TestAudioClipOGG");
2.  
3.         while (acTask.IsCompleted == false)
4.         {
5.             UnityEngine.Debug.Log("Loading AudioClip...");
6.             yield return new WaitForSeconds(0.1f);
7.         }
8.  
9.         AudioClip testAudioClip = acTask.Result;
10.  
11.         audioSource.PlayOneShot(testAudioClip);

 

This error will occurs when we are trying to access a local file content using WWW. There we have to provide the protocol field as "file://" otherwise it will consider as a normal URL and trying to reach the address.

Change the below code

Code (CSharp):

1.        
2.         string localFilePath = Path.Combine(Application.persistentDataPath, fileName);
3.         WWW www = new WWW(localFilePath);
4.         yield return www;
5.         if (!string.IsNullOrEmpty(www.error))
6.         {
7.             Debug.LogError("Error while loading file : " + www.error);
8.             yield break;
9.         }
10.  

to

Code (CSharp):

1.        
2.         string localFilePath = Path.Combine(Application.persistentDataPath, fileName);
3.         WWW www = new WWW("file://" + localFilePath);
4.         yield return www;
5.         if (!string.IsNullOrEmpty(www.error))
6.         {
7.             Debug.LogError("Error while loading file : " + www.error);
8.             yield break;
9.         }
10.