open failed: EACCES (Permission denied)

问题

I am having a very weird problem with storage accessing on some devices. The app works on my testing devices (Nexus 4 & 7, Samsung GS5). All my devices running Android 4.4.2. But I received many emails from users saying that the app can not write to the storage (neither the internal storage nor the sd card). From the log file received from user feedback, I can see the problem is the following code:

try {
    if (fStream == null) {
    fStream = new FileOutputStream(filename, true);
}
    fStream.write(data, 0, bytes);
    return;
} catch (IOException ex) {
    ex.printStackTrace();
}

It throws exception at the line fStream = new FileOutputStream(filename, true); when creating FileOutputStream.

The stack log is:

W/System.err( 8147): Caused by: java.io.FileNotFoundException: /storage/emulated/0/my_folder/test_file_name.png: open failed: EACCES (Permission denied)
w/System.err( 8147):    at libcore.io.IoBridge.open(IoBridge.java:409)
W/System.err( 8147):    at java.io.FileOutputStream.<init>(FileOutputStream.java:88)
W/System.err( 8147):    at java.io.FileOutputStream.<init>(FileOutputStream.java:128)
W/System.err( 8147):    at myapp.save(SourceFile:515)
W/System.err( 8147):    ... 8 more
W/System.err( 8147): Caused by: libcore.io.ErrnoException: open failed: EACCES (Permission denied)
W/System.err( 8147):    at libcore.io.Posix.open(Native Method)
W/System.err( 8147):    at libcore.io.BlockGuardOs.open(BlockGuardOs.java:110)
W/System.err( 8147):    at libcore.io.IoBridge.open(IoBridge.java:393)
W/System.err( 8147):    ... 11 more

In the AndroidManifest.xml I have the following permissions declared:

 <uses-sdk android:minSdkVersion=\"14\" android:targetSdkVersion=\"19\"/>
    <uses-permission android:name=\"android.permission.INTERNET\"/>
<uses-permission android:name=\"android.permission.ACCESS_NETWORK_STATE\"/>
<uses-permission android:name=\"android.permission.ACCESS_WIFI_STATE\"/>
<uses-permission android:name=\"android.permission.READ_EXTERNAL_STORAGE\" />
<uses-permission android:name=\"android.permission.WRITE_EXTERNAL_STORAGE\"/>

I\'ve confirmed that the users are using the correct app\'s private on the SD card. And what\'s more weird is that it fails to write to internal storage as well. How can this happen if I have both read & write permissions? The users say they are not connecting their devices to the PC at that time.

Update

It turns out I am calling open and close FileOutputStream too frequently, which throws the FileNotFoundException at some point. Sounds more like a threading issue.

回答1:

I ran into a similar issue a while back.

Your problem could be in two different areas. It's either how you're creating the file to write to, or your method of writing could be flawed in that it is phone dependent.

If you're writing the file to a specific location on the SD card, try using Environment variables. They should always point to a valid location. Here's an example to write to the downloads folder:

java.io.File xmlFile = new java.io.File(Environment
    .getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS)
     + "/Filename.xml");

If you're writing the file to the application's internal storage. Try this example:

java.io.File xmlFile = new java.io.File((getActivity()
   .getApplicationContext().getFileStreamPath("FileName.xml")
   .getPath()));

Personally I rely on external libraries to handle the streaming to file. This one hasn't failed me yet.

org.apache.commons.io.FileUtils.copyInputStreamToFile(is, file);

I've lost data one too many times on a failed write command, so I rely on well-known and tested libraries for my IO heavy lifting.

If the files are large, you may also want to look into running the IO in the background, or use callbacks.

If you're already using environment variables, it could be a permissions issue. Check out Justin Fiedler's answer below.

回答2:

For API 23+ you need to request the read/write permissions even if they are already in your manifest.

// Storage Permissions
private static final int REQUEST_EXTERNAL_STORAGE = 1;
private static String[] PERMISSIONS_STORAGE = {
        Manifest.permission.READ_EXTERNAL_STORAGE,
        Manifest.permission.WRITE_EXTERNAL_STORAGE
};

/**
 * Checks if the app has permission to write to device storage
 *
 * If the app does not has permission then the user will be prompted to grant permissions
 *
 * @param activity
 */
public static void verifyStoragePermissions(Activity activity) {
    // Check if we have write permission
    int permission = ActivityCompat.checkSelfPermission(activity, Manifest.permission.WRITE_EXTERNAL_STORAGE);

    if (permission != PackageManager.PERMISSION_GRANTED) {
        // We don't have permission so prompt the user
        ActivityCompat.requestPermissions(
                activity,
                PERMISSIONS_STORAGE,
                REQUEST_EXTERNAL_STORAGE
        );
    }
}

AndroidManifest.xml

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

回答3:

Apps targeting Android Q - API 29 by default are given a filtered view into external storage. A quick fix for that is to add this code in the AndroidManifest.xml:

<manifest ... >
    <!-- This attribute is "false" by default on apps targeting Android Q. -->
    <application android:requestLegacyExternalStorage="true" ... >
     ...
    </application>
</manifest>

Read more about it here: https://developer.android.com/preview/privacy/scoped-storage

回答4:

In my case I had the wrong case in

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

android.permission must be lowercase, and somehow the entire string was uppercase in our source.

回答5:

I also faced the same issue. After lot of hard work, I found what was wrong in my case. My device was connected to computer via USB cable. There are types for USB connections like Mass Storage, Media Device(MTP), Camera(PTP) etc. My connection type was - 'Mass Storage', and this was causing the problems. When I changed the connection type, the issue was solved.

Always remember while accessing filesystem on android device :-

DON'T CONNECT AS MASS STORAGE to the computer/pc.

回答6:

In my case it was permissions issue. The catch is that on device with Android 4.0.4 I got access to file without any error or exception. And on device with Android 5.1 it failed with ACCESS exception (open failed: EACCES (Permission denied)). Handled it with adding follow permission to manifest file:

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

So I guess that it's the difference between permissions management in OS versions that causes to failures.

回答7:

First give or check permissions like

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

If these two permissions are OK, then check your output streams are in correct format.

Example:

FileOutputStream fos=new FileOutputStream(Environment.getExternalStorageDirectory()+"/rahul1.jpg");

回答8:

I ran into the same problem and found that I have to request the permissions at run time, even if I have declared it in the manifest. Just as stated as Justin Fiedler's answer.

The official documentation about this are here: https://developer.android.com/training/permissions/requesting.html

My implementation is slightly different from Justin Fiedler's answer that it also implement v4 fragment's onRequestPermissionsResult method to handle the permissions request response.

public static final int REQUEST_EXTERNAL_PERMISSION_CODE = 666;

@RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN)
public static final String[] PERMISSIONS_EXTERNAL_STORAGE = {
        READ_EXTERNAL_STORAGE,
        WRITE_EXTERNAL_STORAGE
};

public boolean checkExternalStoragePermission(Activity activity) {
    if (android.os.Build.VERSION.SDK_INT < android.os.Build.VERSION_CODES.JELLY_BEAN) {
        return true;
    }

    int readStoragePermissionState = ContextCompat.checkSelfPermission(activity, READ_EXTERNAL_STORAGE);
    int writeStoragePermissionState = ContextCompat.checkSelfPermission(activity, WRITE_EXTERNAL_STORAGE);
    boolean externalStoragePermissionGranted = readStoragePermissionState == PackageManager.PERMISSION_GRANTED &&
            writeStoragePermissionState == PackageManager.PERMISSION_GRANTED;
    if (!externalStoragePermissionGranted) {
        requestPermissions(PERMISSIONS_EXTERNAL_STORAGE, REQUEST_EXTERNAL_PERMISSION_CODE);
    }

    return externalStoragePermissionGranted;
}

@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
        if (requestCode == REQUEST_EXTERNAL_PERMISSION_CODE) {
            if (checkExternalStoragePermission(getActivity())) {
                // Continue with your action after permission request succeed
            }
        }
    }
}

回答9:

In my case I used the option android:isolatedProcess="true" for a service in the AndroidManifest.xml.

As soon as I removed it, the error disappeared...

回答10:

Also I found solving for my way.

Before launch app i granted root to file-explorer and did not disable permission on write/read when exit from app.

My app can not use external memory while i did restrat device for resetting all permissions.

回答11:

I got the same issue but Sometimes, the most dificult issue get simple answer.

I recheck the manifest permisions and there WAS_NOT write permision shame of me!!!

回答12:

If the clients are using Android 6.0, Android added new permission model for (Marshmallow).

Trick: If you are targeting version 22 or below, your application will request all permissions at install time just as it would on any device running an OS below Marshmallow

回答13:

In my case the issue was the WIFI Configuration that was static had a conflict with another device using the same IP Address.

回答14:

@Uriel Frankel is correct that the Android 10 storage access has changed. But the right way is not to use legacy storage flag but to request the storage of your app like so:

val screenShotDirPath = getApplication<Application>().getExternalFilesDir(Environment.DIRECTORY_PICTURES)?.path

getExternalFilesDir is what you need.

回答15:

in my case i forgot to add / in front of file name after i added i got rid of from it

bitmap.compress(Bitmap.CompressFormat.PNG,100,new FileOutputStream(Environment.getExternalStorageDirectory()+"/arjunreddy.png"));

来源：https://stackoverflow.com/questions/23527767/open-failed-eacces-permission-denied

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android

filenotfoundexception