My app has .txt files in subdirectories in the assets folder. It reads those .txt files and puts them in a textview. It's working great and no problems.
Should I be concerned about the files in the assets folder getting deleted by the user or missing. If this ever could happen, my app would get an error because the file would not be there when it tried to read it into the stream.
Is there a need for me to check the existence of an asset file before I read it or does the asset manager take care of it all? I also was wondering if there's a chance that a user would or could delete and asset file.
Like I say, everything works fine without me inserting code to check for file existence. I just wondered if people use the .exists() statement every time they go to read in a stream from assets.
You may be concerned that the file have been removed and the apk resigned
You can check using:
Arrays.asList(getResources().getAssets().list("")).contains("myFile")
if you really want to check for the file existence:
AssetManager mg = getResources().getAssets();
InputStream is = null;
try {
is = mg.open(pathInAssets);
//File exists so do something with it
} catch (IOException ex) {
//file does not exist
} finally {
if (is != null) {
is.close();
}
}
If your file is located in assets/folder/file.ext, then pathInAssets would be
"folder/file.ext"
Ideally after apk is built, nobody can remove any assets from it, but if someone decompiled it and recompiles than it may be possible.
Though for other scenarios also when an asset is not present in apk at Runtime, we can check the existence of asset.
In our app, we have a provision to build app using gradle, ant and eclipse, and for each build mechanism some of our assets file are bundled in apk and some are not, so to identify if any asset file is present in current build apk at runtime,
we do this as follows:
private boolean isAssetExists(String pathInAssetsDir){
AssetManager assetManager = AppContext.get().getResources().getAssets();
InputStream inputStream = null;
try {
inputStream = assetManager.open(pathInAssetsDir);
if(null != inputStream ) {
return true;
}
} catch(IOException e) {
e.printStackTrace();
} finally {
try {
inputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return false;
}
Yes and No.
A normal user would not be able to delete them, but a user on a rooted phone who doesn't know what they're doing… that's a different situation.
If you ask me, the extra code is not needed. Also if you try and open a file that doesn't exist, you will get an exception thrown at some point, catch that and display a dialog if you really want to.
AssetManager am = getAssets();
try {
List<String> mapList = Arrays.asList(am.list("path/in/assets/folder"));
if (mapList.contains("file_to_check")) {
Log.e("ERROR", "exists");
} else {
Log.e("ERROR", "not exists");
}
} catch ( IOException ex){
ex.printStackTrace();
}
Convert to function or method can be easy ;)
I think you should be OK. From having a root around in my phone I can't see any way of deleting the assests without deleting the app as it all seems to be wrapped up in the .apk file. You can do it but I think you need to be rooted or use adb.
I would personally surround any reading/writing with a try/catch block anyway, just to be safe.
Related
Having a problem writing out to a file, this code is taken directly from the android developer page and then tweaked a bit by me. Is there something i am missing? Quite new to Android development so sorry if it's something blatantly obvious.
send.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
FileOutputStream outputStream;
String data = "hello";
File fileDir = new File("data.txt");
if (!fileDir.exists())
fileDir.mkdirs();
try {
outputStream = openFileOutput("data.txt",Context.MODE_PRIVATE);
outputStream.write(data.getBytes());
outputStream.close();
} catch (Exception e) {
e.printStackTrace();
}
}
});
Basically, your problem is that you are trying to do it twice, once in a way that won't work, and once in a way that will, but hides the result.
File fileDir = new File("data.txt");
if (!fileDir.exists())
fileDir.mkdirs();
This would create a Java File object connected to a hypothetical file called "data.txt" located in the current working directory, which for an Android app is the root directory of the device - a place you most definitely are not allowed to write to. However, this may not obviously cause any errors, as the root directory exists so mkdirs() will do nothing, and you only create a File object, you don't actually try to create a file on "disk". Effectively this code does nothing for you - get rid of it.
Next you try something basically workable:
try {
outputStream = openFileOutput("data.txt",Context.MODE_PRIVATE);
outputStream.write(data.getBytes());
outputStream.close();
} catch (Exception e) {
e.printStackTrace();
}
openFileOutput() is a method of a Context (Activity or Service) which creates an output stream to write to an actual file located in the private internal storage area of your app. This is all fine and good, and normally a good choice for storing typical data. However, it is not a place that you will be able to examine when running a release app on a secured device, as neither ADB based tools nor Mass Storage or MTP access over USB have rights to it. So it's entirely possible that this code worked, but you had no way to discover that fact. If you are on an emulator, you can access this location with ADB or the DDMS browser, and if your apk is a debug one, you can use the run-as command line tool in the shell.
If you want to share the data, you might consider putting it on the External Storage instead.
I have been trying for the last couple of days to find the right way of writing a file to a subdirectory of the android data folder.
Most answers i found were not clear or didn't address the problem in a right and working way so i finally decided to ask.
I am giving a user the possibility of backing up his data on my server by basically uploading the database to the server through a php script.
The database is located in
'/data/data/com.package/databases/data.db'
The problem here is when a user wants to reload a backed up database.
The application Downloads the file and should then write it (Overwriting the old one) to the /databases/data.db' file, and then reload.
I have managed to get everything to work up until where i have to write the downloaded file because FileOutputStream throws an illegal argument exception saying that i can't use path separators in the path.
I understand that FileOutputStream can only write to the first level of the data folder and not to subdirectories.
How can this be done?
If it can't be done, is there any way to set the default database path to the first level of the 'data' directory to solve this problem?
If this is a completely wrong approach to what i want to obtain i am open to critique but it would still be nice to get an answer, just for future knowing.
public void aSyncDatabaseDownloadFileFinish(PhpWrapper feed) {
if (validateServerResponse(feed.Result)) {
// Copy Database to Directory
try {
FileOutputStream fos = ctx.openFileOutput(ctx.getDatabasePath(DataDatabaseHelper.DBNAME).getAbsolutePath(),
Context.MODE_PRIVATE);
fos.write(feed.DownloadedBytes, 0, feed.DownloadedBytes.length);
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
else
Toast.makeText(ctx, ctx.getResources().getString(R.string.nofilesonserver), Toast.LENGTH_SHORT).show();
}
Thanks in advance.
How can this be done?
In your case, use getDatabasePath() to write a file into the standard location for databases for your app.
Regardless of your path separator issue, openFileOutput() will work with files/ directory in your internal storage, not the databases/ directory.
Ok,
I got the answer thanks to Squonk, Still can't believe that it was that simple.
For anybody having the same problem here is an example:
if (validateServerResponse(feed.Result)) {
// Copy Database to Directory
try {
// This Solved the Exception
FileOutputStream fos = new FileOutputStream(ctx.getDatabasePath(DataDatabaseHelper.DBNAME), true);
fos.write(feed.DownloadedBytes, 0, feed.DownloadedBytes.length);
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
else
Toast.makeText(ctx, ctx.getResources().getString(R.string.nofilesonserver), Toast.LENGTH_SHORT).show();
Thank you Squonk!
Well I am debugging my android application on phone. There is a File Explorer in Eclipse, where I can navigate and delete some files if I want to. My application's database file is under "/data" (by default) but using the Eclipse's File Explorer I don't have access to this folder.
So my question is 'Why I don't have access'?
and
Is there a way for accessing this folder?
Thank you!
...
The way I am deleting my database file is:
context.deleteDatabase(DATABASE_NAME);
Try this:
private void writeToSD() throws IOException {
File f=new File("/data/data/yourPackageName/databases/DatabaseName");
FileInputStream fis=null;
FileOutputStream fos=null;
try{
fis=new FileInputStream(f);
fos=new FileOutputStream("/mnt/sdcard/dump.db");
while(true){
int i=fis.read();
if(i!=-1){
fos.write(i);
}
else{
break;
}
}
fos.flush();
}
catch(Exception e){
e.printStackTrace();
}
finally{
try{
fos.close();
fis.close();
}
catch(IOException ioe){
System.out.println(ioe);
}
}
}
Check for the exception when you call this file from within a try catch block, that will get you started. Cheers!!
So my question is 'Why I don't have access'?
You probably do not have read and write permissions to the folder
Is there a way for accessing this folder?
Yes. You need to have root access and remount the folder with read write permissions.
You need root access. Typically your device has to be rooted before you can do that.
Find out more about rooting:
http://www.androidcentral.com/root
Because your phone isn't rooted so Eclipse/DDMS doesn't have permission to view that folder. Which is quite correct from a security standpoint, otherwise you could edit/delete/compromise any app's data, not just your own.
I would like to make a xml file that will be modified during the execution of the application and i want to keep it after i close it for the next time i open it.
The first problem is that i don't know where do i have to put the file in the package explorer on Eclipse.
If i put the file on res/raw/ folder i could just read the file, but i can't modify.
I'm working with Jdom2.
The file is a score table for a game that will be modified every time the player finish a game.
That's the code i actually have to read the xml file stored on res/raw
try
{
puntf = getResources().openRawResource(R.raw.punt);
} catch (Exception ex)
{
Log.e("Ficheros", "Error");
}
And that's the code i actually have to modify the xml file(with Jdom2). But of course, that is wrong.
public void escritura()
{
try
{
xmlOutput.output(puntu, new FileOutputStream("punt.xml"));
}
catch (Exception e) {
e.printStackTrace();
}
}
Thanks a lot for your answers.
If you want to save a file and modify it programmatically I would suggest you to store it in this path:
/data/data/com.yourpackage.app/punt.xml
I have never worked with Jdom2, but you can have access to it by adding these lines of code:
File puntFile= new File("data/data/com.yourpackage.app/punt.xml");
FileOutputStream fos = new FileOutputStream(puntFile);
xmlOutput.output(puntu, fos);
You can also see the file in DDMS in file explorer. Just follow that path.
I can't understand if you want to save and edit the file during the process of your application or just save it somewhere before the app starts and edit it afterwords. If so, please give more details about that.
Hope I helped...
You should read uo on storage options on Andriod: THere's an article on this.... Use the resulting input and output streams for JDOM.
First: see my question Reading XML online and Storing It (Using Java). Read the approved answers and the comments underneath that answer.
So, what my question here is: even though I've run through the process described in the linked question, and the .xml file saves to the /res/values folder in my Android App, its not showing up at all - not when I'm running the app, nor after I close the app.
Does anyone have any ideas on how to fix this so that when I generate the file, it will be available right away, even while the app is running, to read and use?
just use this code,
FileOutputStream fOut = null;
try {
fOut = this.openFileOutput("your xml file name.xml", MODE_PRIVATE);
try {
InputStream is = new FileInputStream("your source file");
int size = is.available();
byte[] buffer = new byte[size];
is.read(buffer);
is.close();
fOut.write(buffer);
} catch(Exception e) {
e.printStackTrace();
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} finally {
try {
fOut.close();
} catch (IOException e) {
e.printStackTrace();
}
}
and you can see your xml file at the data/data/packagename/file folder Thnx. Hope this will help you.
I'm not 100% sure if you're running the XML parsing in Java or actually in your Android app.
If you're running in Java, be aware that your project structure isn't live in the emulator - the .apk was packaged up and installed before running. You need to use adb to push files into the emulator (or your Android device) before your app can see the file.
If you're accessing the file in the app:
If you use file access methods such as openFileOutput() it will show up in the private directory on the device, which would be /data/data//files/
However, if you're using "new File(" rather than "context.openFileOutput" then the file is wherever you put it.