Question

我想从SD卡中选择图片并对其进行加密。我对java io异常有一些问题-权限被拒绝。我在android清单READ和WRITE EXTERNAL STORAGE中声明了使用权限，但不起作用

然后我打开设备文件资源管理器并检查权限，所有这些人都没有写权限

我的代码：

File file = new File(uri_result);//create path from uri
            final String[] split = file.getPath().split(":");//split the path.
            String filePath = split[2];

            try {
                FileInputStream fis = new FileInputStream(filePath);
                File fos_enc = new File( Environment.getExternalStorageDirectory().getAbsolutePath()+"/abcd.jpg");
                fos_enc.createNewFile();
                FileOutputStream fos = new FileOutputStream(fos_enc);

                byte[] k = "123456".getBytes();
                SecretKeySpec key = new SecretKeySpec(k,"DES");
                Cipher enc = Cipher.getInstance("DES");
                enc.init(Cipher.ENCRYPT_MODE, key);
                CipherOutputStream cos = new CipherOutputStream(fos, enc);
                byte[] buf = new byte[1024];
                int read;
                while ((read = fis.read(buf)) != -1) {
                    cos.write(buf,0,read);
                }
                fis.close();
                fos.flush();
                cos.close();
                showAlertDialog("Encrypt Successfully");
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (NoSuchPaddingException e) {
                e.printStackTrace();
            } catch (NoSuchAlgorithmException e) {
                e.printStackTrace();
            } catch (InvalidKeyException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }

权限被拒绝，因为sdcard无法访问写入文件，而且我不知道要解决此问题。请帮助我:)
fos_enc = newFile（Environment.getExternalStorageDirectory（）。getAbsolutePath（）+“ / abcd.jpg”）;

Answer 1

使用外部存储需要获得用户的许可。您需要在运行时向用户询问。 Check this doc。或在测试应用程序设置中手动访问权限。

Answer 2

您需要为其添加权限。因为您需要外部文件的读写权限

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

您需要先在运行时请求权限，然后再执行以下操作（对于使用棒棒糖的设备以及android os以上的设备，这是必需的）

if (ContextCompat.checkSelfPermission(thisActivity,Manifest.permission.WRITE_EXTERNAL_STORAGE)!= PackageManager.PERMISSION_GRANTED) {
    // Permission is not granted
     if (ActivityCompat.shouldShowRequestPermissionRationale(thisActivity,
            Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
        // Show an explanation to the user *asynchronously* -- don't block
        // this thread waiting for the user's response! After the user
        // sees the explanation, try again to request the permission.
    } else {
        // No explanation needed; request the permission
        ActivityCompat.requestPermissions(thisActivity,
                new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
                MY_PERMISSIONS_WRITE_EXTERNAL_STORAGE);
    }
}

Answer 3

android:requestLegacyExternalStorage="true" 解决了我的问题

创建文件时android中的权限被拒绝

3 个答案: