Looking at this issue xamarin/Essentials#1322, how do I download a file on both Android ( versions 6-10, Api 23-29 ) and iOS ( version 13.1+ ) that is publicly available (share-able to other apps, such as Microsoft Word). I don't need to give write access to the other apps, just read-only is ok if it must be restricted.
I get the following exception:
[Bug] Android.OS.FileUriExposedException: file:///data/user/0/{AppBundleName}/cache/file.doc exposed beyond app through Intent.getData()
With the following code.
public static string GetCacheDataPath( string fileName ) => Path.Combine(Xamarin.Essentials.FileSystem.CacheDirectory, fileName);
public static FileInfo SaveFile( string filename, Uri link )
{
using var client = new WebClient();
string path = GetCacheDataPath(filename);
DebugTools.PrintMessage(path);
client.DownloadFile(link, path);
return new FileInfo(path);
}
public async Task Test(Uri link)
{
LocalFile path = await SaveFile("file.doc", link).ConfigureAwait(true);
var url = new Uri($"ms-word://{path.FullName}", UriKind.Absolute);
await Xamarin.Essentials.Launcher.OpenAsync(url).ConfigureAwait(true);
}
With this answer, I created a FileService interface and it works with local private files but I am unable to share the files. Starting with Android Q (10 / Api 29), the following is deprecated.
string path = Android.OS.Environment.GetExternalStoragePublicDirectory(Android.OS.Environment.DirectoryDownloads).AbsolutePath; // deprecated
I get the following exception:
System.UnauthorizedAccessException: Access to the path '/storage/emulated/0/Download/file.doc' is denied. ---> System.IO.IOException: Permission denied
I haven't found any way yet to get a public path for Android 10 with Xamarin.Forms. I've looked at the Android Docs for Content providers but it's in Java, and I can't get it working in C# yet.
Any help would be greatly appreciated.
I did find a Solution
Found a fix
For Android
public Task<System.IO.FileInfo> DownloadFile( Uri link, string fileName )
{
if ( link is null )
throw new ArgumentNullException(nameof(link));
using System.Net.WebClient client = new System.Net.WebClient();
// MainActivity is the class that loads the application.
// MainActivity.Instance is a property that you set "Instance = this;" inside of OnCreate.
Java.IO.File root = MainActivity.Instance.GetExternalFilesDir(MediaStore.Downloads.ContentType);
string path = Path.Combine(root.AbsolutePath, fileName);
client.DownloadFile(link, path);
return Task.FromResult(new System.IO.FileInfo(path));
}
public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity
{
internal static MainActivity Instance { get; private set; }
protected override void OnCreate(Bundle savedInstanceState)
{
...
Instance = this;
...
}
...
}
For iOS
public Task<System.IO.FileInfo> DownloadFile( Uri link, string fileName )
{
if ( link is null )
throw new ArgumentNullException(nameof(link));
using System.Net.WebClient client = new System.Net.WebClient();
string path = Path.Combine(Xamarin.Essentials.FileSystem.CacheDirectory, fileName)
client.DownloadFile(link, path);
return Task.FromResult(new System.IO.FileInfo(path));
}
public async Task Share()
{
// back in shared project, choose a file name and pass the link.
System.IO.FileInfo info = await DependencyService.Get<IDownload>().DownloadFile(new Uri("<enter site>", "file.doc").ConfigureAwait(true);
ShareFile shareFile = new ShareFile(info.FullName, "doc"); // enter the file type / extension.
var request = new ShareFileRequest("Choose the App to open the file", shareFile);
await Xamarin.Essentials.Share.RequestAsync(request).ConfigureAwait(true);
}
Note that for iOS, due to Apple's infinite wisdom... I cannot share the file directly with another app as I can on Android. Sandboxing is good for security but in this case, how they implemented it, it limits options. Both Applications must be pre-registered / pre-allocated in an "App Group" to share files directly. See this Article and the Apple Docs for more information.
So in my app i pass a game object, called datacontroller through out my three scenes. The persistent scene is an empty scene, the menuscreen scene and then the game scene. My application works perfectly on my computer and in editor mode but when i download the apk to my android tablet it no longer works! iv'e read this may have to do with my code for my object but i dont think i written anything that only works in the editor.
enter code here
using UnityEngine;
using UnityEngine.SceneManagement;
using System.Collections;
using System.IO; // The System.IO namespace contains functions related to loading and saving
files
public class DataController : MonoBehaviour
{
private RoundData[] allRoundData;
private PlayerProgress playerProgress;
private string gameDataFileName = "data.json";
void Start()
{
DontDestroyOnLoad(gameObject);
LoadGameData();
LoadPlayerProgress();
SceneManager.LoadScene("MenuScreen");
}
public RoundData GetCurrentRoundData()
{
// If we wanted to return different rounds, we could do that here
// We could store an int representing the current round index in PlayerProgress
return allRoundData[0];
}
public void SubmitNewPlayerScore(int newScore)
{
// If newScore is greater than playerProgress.highestScore, update playerProgress with the new value and call SavePlayerProgress()
if (newScore > playerProgress.highestScore)
{
playerProgress.highestScore = newScore;
SavePlayerProgress();
}
}
public int GetHighestPlayerScore()
{
return playerProgress.highestScore;
}
private void LoadGameData()
{
// Path.Combine combines strings into a file path
// Application.StreamingAssets points to Assets/StreamingAssets in the Editor, and the StreamingAssets folder in a build
string filePath = Path.Combine(Application.streamingAssetsPath, gameDataFileName);
if (File.Exists(filePath))
{
// Read the json from the file into a string
string dataAsJson = File.ReadAllText(filePath);
// Pass the json to JsonUtility, and tell it to create a GameData object from it
GameData loadedData = JsonUtility.FromJson<GameData>(dataAsJson);
// Retrieve the allRoundData property of loadedData
allRoundData = loadedData.allRoundData;
}
else
{
Debug.LogError("Cannot load game data!");
}
}
// This function could be extended easily to handle any additional data we wanted to store in our PlayerProgress object
private void LoadPlayerProgress()
{
// Create a new PlayerProgress object
playerProgress = new PlayerProgress();
// If PlayerPrefs contains a key called "highestScore", set the value of playerProgress.highestScore using the value associated with that key
if (PlayerPrefs.HasKey("highestScore"))
{
playerProgress.highestScore = PlayerPrefs.GetInt("highestScore");
}
}
// This function could be extended easily to handle any additional data we wanted to store in our PlayerProgress object
private void SavePlayerProgress()
{
// Save the value playerProgress.highestScore to PlayerPrefs, with a key of "highestScore"
PlayerPrefs.SetInt("highestScore", playerProgress.highestScore);
}
}
I am starting to go through tutorials of unity myself so I am not an expert. :)
But what I would try is the first thing. using System.IO; not sure if this will work to get files on android because android has a different file structure. So I would first remove it and sort of hard code the file path or comment out the code using System.IO classes then recompile apk in unity and check if it works. I also saw this post : http://answers.unity3d.com/questions/1023391/systemio-dont-work-on-android.html
If that did not work I would comment functionality out and compile apk and check if its working if its not comment more code out until you find the line or the code that causes it to error on android. This method takes long to troubleshoot or get your code causing the problem but for me this has worked before.
I am guessing as it is working on you pc its a class or something its referencing that's not available in android.
Please share your findings if you figure out what part of the code does it. As I would also want to know to prevent me from doing it. :)
Avoid the use of System.IO on Android and in general on Unity.
Use "Resources" instead, just following this steps:
Create a folder called "Resources"
Move json file on it and rename in .txt
Use this code to get the string:
var file = Resources.Load("filename_here") as TextAsset;
Debug.Log(file.text)
I am building a Xamarin.Forms project with a PCL, iOS and Android project. One of my requirements is that I have to read a JSON file stored in the platform project (iOS/Android) from the PCL.
How can I do this please? I can't find a solution for this problem. :(
Thank you very much,
Nikolai
If the file that you want to read is embedded in the platform project assembly you can use the following code:
var assembly = typeof(MyPage).GetTypeInfo().Assembly;
Stream stream = assembly.GetManifestResourceStream("WorkingWithFiles.PCLTextResource.txt");
string text = "";
using (var reader = new System.IO.StreamReader (stream)) {
text = reader.ReadToEnd ();
}
Make sure that you replace WorkingWithFiles with namespace of your project and PCLTextResource.txt with name of the file.
Check Xamarin documentation at Loading Files Embedded as Resources for more details
If on the other hand you want to create and read/write files at runtime you can use PCLStorage library:
public async Task PCLStorageSample()
{
IFolder rootFolder = FileSystem.Current.LocalStorage;
IFolder folder = await rootFolder.CreateFolderAsync("MySubFolder",
CreationCollisionOption.OpenIfExists);
IFile file = await folder.CreateFileAsync("answer.txt",
CreationCollisionOption.ReplaceExisting);
await file.WriteAllTextAsync("42");
}
I got it working by using an IoC container.
In my iOS project I have created a ConfigAccess class:
public class ConfigAccess : IConfigAccess
{
public string ReadConfigAsString()
{
return System.IO.File.ReadAllText("config.json");
}
}
I also had to add the following line to my AppDelegate.cs
SimpleIoc.Default.Register<IConfigAccess, ConfigAccess>();
And in my PCL I am simply asking for a ConfigAccess object during runtime:
var configAccess = SimpleIoc.Default.GetInstance<IConfigAccess>();
var test = configAccess.ReadConfigAsString();
Is there a Java equivalent for System.IO.Path.Combine() in C#/.NET? Or any code to accomplish this?
This static method combines one or more strings into a path.
Rather than keeping everything string-based, you should use a class which is designed to represent a file system path.
If you're using Java 7 or Java 8, you should strongly consider using java.nio.file.Path; Path.resolve can be used to combine one path with another, or with a string. The Paths helper class is useful too. For example:
Path path = Paths.get("foo", "bar", "baz.txt");
If you need to cater for pre-Java-7 environments, you can use java.io.File, like this:
File baseDirectory = new File("foo");
File subDirectory = new File(baseDirectory, "bar");
File fileInDirectory = new File(subDirectory, "baz.txt");
If you want it back as a string later, you can call getPath(). Indeed, if you really wanted to mimic Path.Combine, you could just write something like:
public static String combine(String path1, String path2)
{
File file1 = new File(path1);
File file2 = new File(file1, path2);
return file2.getPath();
}
In Java 7, you should use resolve:
Path newPath = path.resolve(childPath);
While the NIO2 Path class may seem a bit redundant to File with an unnecessarily different API, it is in fact subtly more elegant and robust.
Note that Paths.get() (as suggested by someone else) doesn't have an overload taking a Path, and doing Paths.get(path.toString(), childPath) is NOT the same thing as resolve(). From the Paths.get() docs:
Note that while this method is very convenient, using it will imply an assumed reference to the default FileSystem and limit the utility of the calling code. Hence it should not be used in library code intended for flexible reuse. A more flexible alternative is to use an existing Path instance as an anchor, such as:
Path dir = ...
Path path = dir.resolve("file");
The sister function to resolve is the excellent relativize:
Path childPath = path.relativize(newPath);
The main answer is to use File objects. However Commons IO does have a class FilenameUtils that can do this kind of thing, such as the concat() method.
platform independent approach (uses File.separator, ie will works depends on operation system where code is running:
java.nio.file.Paths.get(".", "path", "to", "file.txt")
// relative unix path: ./path/to/file.txt
// relative windows path: .\path\to\filee.txt
java.nio.file.Paths.get("/", "path", "to", "file.txt")
// absolute unix path: /path/to/filee.txt
// windows network drive path: \\path\to\file.txt
java.nio.file.Paths.get("C:", "path", "to", "file.txt")
// absolute windows path: C:\path\to\file.txt
I know its a long time since Jon's original answer, but I had a similar requirement to the OP.
By way of extending Jon's solution I came up with the following, which will take one or more path segments takes as many path segments that you can throw at it.
Usage
Path.combine("/Users/beardtwizzle/");
Path.combine("/", "Users", "beardtwizzle");
Path.combine(new String[] { "/", "Users", "beardtwizzle", "arrayUsage" });
Code here for others with a similar problem
public class Path {
public static String combine(String... paths)
{
File file = new File(paths[0]);
for (int i = 1; i < paths.length ; i++) {
file = new File(file, paths[i]);
}
return file.getPath();
}
}
To enhance JodaStephen's answer, Apache Commons IO has FilenameUtils which does this. Example (on Linux):
assert org.apache.commons.io.FilenameUtils.concat("/home/bob", "work\\stuff.log") == "/home/bob/work/stuff.log"
It's platform independent and will produce whatever separators your system needs.
Late to the party perhaps, but I wanted to share my take on this. I prefer not to pull in entire libraries for something like this. Instead, I'm using a Builder pattern and allow conveniently chained append(more) calls. It even allows mixing File and String, and can easily be extended to support Path as well. Furthermore, it automatically handles the different path separators correctly on both Linux, Macintosh, etc.
public class Files {
public static class PathBuilder {
private File file;
private PathBuilder ( File root ) {
file = root;
}
private PathBuilder ( String root ) {
file = new File(root);
}
public PathBuilder append ( File more ) {
file = new File(file, more.getPath()) );
return this;
}
public PathBuilder append ( String more ) {
file = new File(file, more);
return this;
}
public File buildFile () {
return file;
}
}
public static PathBuilder buildPath ( File root ) {
return new PathBuilder(root);
}
public static PathBuilder buildPath ( String root ) {
return new PathBuilder(root);
}
}
Example of usage:
File root = File.listRoots()[0];
String hello = "hello";
String world = "world";
String filename = "warez.lha";
File file = Files.buildPath(root).append(hello).append(world)
.append(filename).buildFile();
String absolute = file.getAbsolutePath();
The resulting absolute will contain something like:
/hello/world/warez.lha
or maybe even:
A:\hello\world\warez.lha
If you do not need more than strings, you can use com.google.common.io.Files
Files.simplifyPath("some/prefix/with//extra///slashes" + "file//name")
to get
"some/prefix/with/extra/slashes/file/name"
Here's a solution which handles multiple path parts and edge conditions:
public static String combinePaths(String ... paths)
{
if ( paths.length == 0)
{
return "";
}
File combined = new File(paths[0]);
int i = 1;
while ( i < paths.length)
{
combined = new File(combined, paths[i]);
++i;
}
return combined.getPath();
}
This also works in Java 8 :
Path file = Paths.get("Some path");
file = Paths.get(file + "Some other path");
This solution offers an interface for joining path fragments from a String[] array. It uses java.io.File.File(String parent, String child):
public static joinPaths(String[] fragments) {
String emptyPath = "";
return buildPath(emptyPath, fragments);
}
private static buildPath(String path, String[] fragments) {
if (path == null || path.isEmpty()) {
path = "";
}
if (fragments == null || fragments.length == 0) {
return "";
}
int pathCurrentSize = path.split("/").length;
int fragmentsLen = fragments.length;
if (pathCurrentSize <= fragmentsLen) {
String newPath = new File(path, fragments[pathCurrentSize - 1]).toString();
path = buildPath(newPath, fragments);
}
return path;
}
Then you can just do:
String[] fragments = {"dir", "anotherDir/", "/filename.txt"};
String path = joinPaths(fragments);
Returns:
"/dir/anotherDir/filename.txt"
Assuming all given paths are absolute paths. you can follow below snippets to merge these paths.
String baseURL = "\\\\host\\testdir\\";
String absoluteFilePath = "\\\\host\\testdir\\Test.txt";;
String mergedPath = Paths.get(baseURL, absoluteFilePath.replaceAll(Matcher.quoteReplacement(baseURL), "")).toString();
output path is \\host\testdir\Test.txt.
The process seemed quite simplistic at first, but there must be something that I am missing going forward with this task. There was a settings file that I wanted to create local to my application for storing a whole bunch of data (not preference worthy). I ended up saving the file with the following code snippet.
protected File createSettingsFileLocation(String fileNameF)
{
File directoryFile = context_.getDir("settings", Context.MODE_PRIVATE);
File settingsFile;
settingsFile = new File(directoryFile, fileNameF);
if (!settingsFile.exists())
{
try
{
settingsFile.createNewFile();
} catch(IOException e)
{
Log.e(MyConstants.LOG_TAG, "Could not create the file as intended within internal storage.");
return null;
}
}
return settingsFile;
}
and then proceeded to retrieve the file later by looking for it locally with the following code snippets.
public String getCurrentFileContainingSettings()
{
List<String >settingFilesInFolder = getLocalStorageFileNames();
if (settingFilesInFolder == null || settingFilesInFolder.isEmpty())
{
return null;
}
String pathToCurrentSettingsFile = settingFilesInFolder.get(0);
return pathToCurrentSettingsFile;
}
protected List<String> getLocalStorageFileNames()
{
return Arrays.asList(context_.fileList());
}
However, the settingFilesInFolder always returns no entries, so I get null back from the getCurrentFileContainingSettings(). As what I could see from the documentation it seems as thought I was doing it right. But, I must be missing something, so I was hoping that someone could point something out to me. I could potentially hard-code the file name once it has been created within the system in a preference file for access later the first time that the settings are created, but I shouldn't have to do something like that I would think.
fileList() only looks in getFilesDir(), not in its subdirectories, such as the one you created via getDir(). Use standard Java file I/O (e.g., list()) instead.