Question

我有一个Android 7.0测试设备和我的APK目标=“targetSdkVersion 22”，其中包含：

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

使用：

final File f = new 
File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES) + File.separator + "DressUpBaby" + photonumber + ".png");
f.createNewFile();

此时我收到警告：

W/System.err: java.io.IOException: Permission denied

如何保存文件？当我在Eclipse上创建它时，这是有效的，但是现在我已经更新并转移到Android Studio，它似乎已经破坏了一些东西。

Answer 1

如果您定位到 SDK 29 ，并且在成功请求WRITE_EXTERNAL_STORAGE权限后仍然出现“拒绝权限”错误，则应添加

android:requestLegacyExternalStorage="true"

转到AndroidManifest.xml中的应用程序定义。

<manifest ... >
  <!-- This attribute is "false" by default on apps targeting
       Android 10 or higher. -->
    <application android:requestLegacyExternalStorage="true" ... >
      ...
    </application>
</manifest>

请参阅https://developer.android.com/training/data-storage/compatibility

Answer 2

如果您在API级别23或更高级别上运行应用程序，则必须在运行时请求权限。

请求权限：

String[] permissions = {Manifest.permission.WRITE_EXTERNAL_STORAGE};
requestPermissions(permissions, WRITE_REQUEST_CODE);

然后处理结果：

@Override
public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
    switch (requestCode) {
       case WRITE_REQUEST_CODE:
         if(grantResults[0] == PackageManager.PERMISSION_GRANTED){
           //Granted.


         }
       else{
           //Denied.
         }
        break;
    }
}

有关详细信息，请访问Requesting Permissions at Run Time - Android Doc

Answer 3

Android N引入了一种新的权限模型，该模式仅在应用程序真正需要时才会请求权限，而不是像以前那样在安装期间。

使用以下代码询问权限

注意 - 还要在清单文件中添加所需的权限

如果您没有要求主要活动的权限传递对上下文/活动的引用

以下示例显示了要求写入外部存储的权限的示例，可以同时重新安排多个permisisons（谷歌不推荐）。

public class MainActivity extends AppCompatActivity {
/**
 * Variables for requiesting permissions, API 25+
 */
private int requestCode;
private int grantResults[];


/** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {if(ContextCompat.checkSelfPermission(this,Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_DENIED ){
        //if you dont have required permissions ask for it (only required for API 23+)
        ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},requestCode);


        onRequestPermissionsResult(requestCode,new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},grantResults);
    }

    @Override // android recommended class to handle permissions
    public void onRequestPermissionsResult(int requestCode,
                                       String permissions[], int[] grantResults) {
        switch (requestCode) {
            case 1: {

            // If request is cancelled, the result arrays are empty.
            if (grantResults.length > 0
                    && grantResults[0] == PackageManager.PERMISSION_GRANTED) {

                Log.d("permission","granted");
            } else {

                // permission denied, boo! Disable the
                // functionality that depends on this permission.uujm
                Toast.makeText(MainActivity.this, "Permission denied to read your External storage", Toast.LENGTH_SHORT).show();

                //app cannot function without this permission for now so close it...
                onDestroy();
            }
            return;
        }

        // other 'case' line to check fosr other
        // permissions this app might request
    }
}

Answer 4

如果即使授予了权限并且您已经实施了权限检查，您也会得到拒绝权限错误，

确保您未定位到api级别29：

将 targetSdkVersion 和 compilesdkversion 从 29 更改为 28 或其他任何较低级别。

Answer 5

与答案“确保您未针对api级别29 ...”有关，我发现了这一点。

https://developer.android.com/reference/android/os/Environment#getExternalStorageDirectory

。。。。。。。。

“ getExternalStoragePublicDirectory”

此方法已在API级别29中弃用。

为了提高用户隐私，不建议直接访问共享/外部存储设备。当应用程序定位到Build.VERSION_CODES.Q时，此方法返回的路径不再可供应用程序直接访问。通过迁移到Context＃getExternalFilesDir（String），MediaStore或Intent＃ACTION_OPEN_DOCUMENT之类的替代方案，应用程序可以继续访问共享/外部存储中存储的内容。

。。。。。。。。

因此，在这种情况下，您必须用其他方法替换“ getExternalStoragePublicDirectory”。

Answer 6

这是我在类似情况下所做的：

步骤1：为清单文件添加权限

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

步骤2：创建权限检查功能

void checkForPermissions()
{
    // Here, thisActivity is the current activity
    if (ContextCompat.checkSelfPermission(this,
            Manifest.permission.WRITE_EXTERNAL_STORAGE)
            != PackageManager.PERMISSION_GRANTED) {

        // Permission is not granted
        // Should we show an explanation?
        if (ActivityCompat.shouldShowRequestPermissionRationale(this,
                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.
            // This part I didn't implement,because for my case it isn't needed
            Log.i(TAG,"Unexpected flow");
        } else {
            // No explanation needed; request the permission
            ActivityCompat.requestPermissions(this,
                    new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
                    MY_PERMISSIONS_REQUEST_EXTERNAL_STORAGE);

            // MY_PERMISSIONS_REQUEST_EXTERNAL_STORAGE is an
            // app-defined int constant. The callback method gets the
            // result of the request.
        }
    } else {
        // Permission is already granted, call the function that does what you need

        onFileWritePermissionGranted();
    }
}

步骤3：实现onRequestPermissionsResult

 @Override
    public void onRequestPermissionsResult(int requestCode,
                                           String[] permissions, int[] grantResults) {
        switch (requestCode) {
            case MY_PERMISSIONS_REQUEST_EXTERNAL_STORAGE: {
                // If request is cancelled, the result arrays are empty.
                if (grantResults.length > 0
                        && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    // permission was granted, yay! 
                    // call the function that does what you need
                    onFileWritePermissionGranted();
                } else {
                    Log.e(TAG, "Write permissions has to be granted tp ATMS, otherwise it cannot operate properly.\n Exiting the program...\n");
                }
                return;
            }

            // other 'case' lines to check for other
            // permissions this app might request.
        }
    }

第4步：使用权限：）

void onFileWritePermissionGranted()
{
   // Write to some file
}

Answer 7

在最新版本的android中，请求权限有点不同，例如，如果您想先访问存储权限您需要从 Manifest.xml 请求访问权限

喜欢：

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

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

最重要的是不要忘记从 Manifets.xml 的应用程序标签中允许这一点，

`android:requestLegacyExternalStorage="true"'

//并从您的活动中创建方法以请求运行权限从任何需要的活动中调用此函数。

private boolean requestPermission(){
        boolean request=true;
        String[] permissions={Manifest.permission.CAMERA,
                                Manifest.permission.ACCESS_FINE_LOCATION,
                                Manifest.permission.READ_EXTERNAL_STORAGE,
                                Manifest.permission.WRITE_EXTERNAL_STORAGE,
                                Manifest.permission.ACCESS_COARSE_LOCATION,
                                Manifest.permission.ACCESS_FINE_LOCATION};
        if (permissions.length!=0){
            ActivityCompat.requestPermissions(this,permissions,102);
            request= true;
        }

        else{
            toastMsg("Permissions Denied");
            println("Permissions not allowed by User...");
            request=false;
        }

        return request;

    }

尽管获得许可，但写入外部存储器的权限仍被拒绝

7 个答案:

确保您未定位到api级别29：

步骤1：为清单文件添加权限

步骤2：创建权限检查功能

步骤3：实现onRequestPermissionsResult

第4步：使用权限：）