java.io.FileNotFoundException: /storage/emulated/0/New file.txt: open failed: EACCES (Permission denied)

I've been trying to encrypt files and write those files back on to the same place. But I got the error message saying "java.io.FileNotFoundException: /storage/emulated/0/New file.txt: open failed: EACCES (Permission denied)".

My Manifest file is this 

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.tdk.mytestapplication2">


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




<application
android:allowBackup="true"

I think I have provided correct permission there. And the code I am using to encrypt files is this. 

public static void encrypt(SecretKey secretKey, String filePath){
try {
// Here you read the cleartext.
FileInputStream fis = new FileInputStream(filePath);
// This stream write the encrypted text. This stream will be wrapped by another stream.
FileOutputStream fos = new FileOutputStream(filePath);


// Create cipher
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, secretKey);
// Wrap the output stream
CipherOutputStream cos = new CipherOutputStream(fos, cipher);


// Write bytes
int b;
byte[] d = new byte[8];
while ((b = fis.read(d)) != -1) {
cos.write(d, 0, b);
}


// Flush and close streams.
cos.flush();
cos.close();
fis.close();


}catch(IOException e){
e.printStackTrace();
}catch (NoSuchAlgorithmException e){
e.printStackTrace();
}catch(NoSuchPaddingException e){
e.printStackTrace();
}catch(InvalidKeyException e){
e.printStackTrace();
}
}

And I used this method inside a button 

Button btnEncrypt = (Button) findViewById(R.id.btnEnc);
btnEncrypt.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
aesKey = EncAndDec.generateKey();
String filePath = editText.getText().toString();
//Generating the file hash
String md5Hash = MD5Hash.getMD5(filePath);


System.out.println(aesKey.toString());
System.out.println(filePath);
System.out.println(md5Hash);


//Encrypting the file
for(int i=1; i<100; i++) {
EncAndDec.encrypt(aesKey, filePath);
}
}
});

Still I couldn't configure this error. Please someone help!

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最佳答案

I suspect you are running Android 6.0 Marshmallow (API 23) or later. If this is the case, you must implement runtime permissions before you try to read/write external storage.

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Implement runtime permission for running your app on Android 6.0 Marshmallow (API 23) or later.

or you can manually enable the storage permission-

goto settings>apps> "your_app_name" >click on it >then click permissions> then enable the storage. Thats it.

But i suggest go the for first one which is, Implement runtime permissions in your code.

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If you are running in Android 29 then you have to use scoped storage or for now, you can bypass this issue by using:

android:requestLegacyExternalStorage="true"

in manifest in the application tag.

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For SDK 29 :

String str1 = "";
folder1 = new File(String.valueOf(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_MOVIES)));
if (folder1.exists()) {str1 = folder1.toString() + File.separator;}


public static void createTextFile(String sBody, String FileName, String Where) {
try {
File gpxfile = new File(Where, FileName);
FileWriter writer = new FileWriter(gpxfile);
writer.append(sBody);
writer.flush();
writer.close();
} catch (IOException e) {
e.printStackTrace();
}
}

Then you can save your file like this :

createTextFile("This is Content","file.txt",str1);
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On Android 11, apps can no longer access files in any other app's dedicated, app-specific directory within external storage. To protect user privacy, on devices that run Android 11 or higher, the system further restricts your app's access to other apps' private directories.

Request MANAGE_EXTERNAL_STORAGE permission

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE"
tools:ignore="ScopedStorage"/>

Request External Storage Permissions

ActivityCompat.requestPermissions( this,
new String[]{
Manifest.permission.READ_EXTERNAL_STORAGE,
Manifest.permission.MANAGE_EXTERNAL_STORAGE
}, 1
);

Checking permission of MANAGE_EXTERNAL_STORAGE

// If you have access to the external storage, do whatever you need
if (Environment.isExternalStorageManager()){


// If you don't have access, launch a new activity to show the user the system's dialog
// to allow access to the external storage
}else{
Intent intent = new Intent();
intent.setAction(Settings.ACTION_MANAGE_APP_ALL_FILES_ACCESS_PERMISSION);
Uri uri = Uri.fromParts("package", this.getPackageName(), null);
intent.setData(uri);
startActivity(intent);
}

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