Android 7.0 中的运行时权限检查

Question

当我尝试在 sdcard 中创建文件时：

newFile.createNewFile();

我得到的日志如下：

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

W/System.err：在 java.io.UnixFileSystem.createFileExclusively0(Native Method)

W/System.err：在 java.io.UnixFileSystem.createFileExclusively(UnixFileSystem.java:280)

W/System.err：在 java.io.File.createNewFile(File.java:948)

我知道原因是没有授予危险的运行时权限（WRITE_EXTERNAL_STORAGE），但是当我尝试在 PackageManagerService.java checkUidPermission() 中打印日志时，发现它没有被调用。

我想知道原生方法（如java.io.UnixFileSystem.createFileExclusively0）如何判断未授予运行时权限？

Answer 1

在 Android M 中，权限可以由用户在运行时授予/撤销，而不是在安装时。

因此，当针对具有 M 及更高版本的设备时，您需要检查权限是否被授予我使用此类来检查权限，希望对您有所帮助：

/**
 * Created by Mani on 17/09/16.
 * Making the runtime app permissions for android marshmallow+ devices cleaner
 * Specify all the requests here
 */
public class MarshMallowPermission {
    private static final int CALL_PERMISSION_REQUEST_CODE = 1;
    public static final int EXTERNAL_STORAGE_PERMISSION_REQUEST_CODE = 2;
    public static final int CAMERA_PERMISSION_REQUEST_CODE = 3;
    public static final int SHORT_CUT_PERMISSION_REQUEST_CODE = 4;
    private Activity activity;


    public MarshMallowPermission(Activity activity) {
        this.activity = activity;
    }

    public boolean checkPermissionForCall(){
        int result = ContextCompat.checkSelfPermission(activity, Manifest.permission.CALL_PHONE);
        return result == PackageManager.PERMISSION_GRANTED;
    }

    @RequiresApi(api = Build.VERSION_CODES.KITKAT)
    public boolean checkPermissionForShortCut(){


        int result = PermissionChecker.checkSelfPermission(activity,Manifest.permission.INSTALL_SHORTCUT);
        return result == PermissionChecker.PERMISSION_GRANTED;
    }


    public boolean checkPermissionForExternalStorage(){
        int result = ContextCompat.checkSelfPermission(activity, Manifest.permission.WRITE_EXTERNAL_STORAGE);
        int readStorage = 0;
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
            readStorage = ContextCompat.checkSelfPermission(activity, Manifest.permission.READ_EXTERNAL_STORAGE);
        }

        return result == PackageManager.PERMISSION_GRANTED && readStorage == PackageManager.PERMISSION_GRANTED;
    }

    public boolean checkPermissionForCamera(){
        int result = ContextCompat.checkSelfPermission(activity, Manifest.permission.CAMERA);
        return result == PackageManager.PERMISSION_GRANTED;
    }


    public void requestPermissionForCall(){
        if (ActivityCompat.shouldShowRequestPermissionRationale(activity, Manifest.permission.CALL_PHONE)){
            Toast.makeText(activity, "Call Phone Permission required to launch Dialer. Please allow in App Settings for additional functionality.", Toast.LENGTH_LONG).show();
        } else {
            ActivityCompat.requestPermissions(activity,new String[]{Manifest.permission.CALL_PHONE},CALL_PERMISSION_REQUEST_CODE);
        }
    }

    public void requestPermissionForExternalStorage(){
        if (ActivityCompat.shouldShowRequestPermissionRationale(activity, Manifest.permission.WRITE_EXTERNAL_STORAGE)){
            Toast.makeText(activity, "External Storage permission required. Please allow in App Settings for additional functionality.", Toast.LENGTH_LONG).show();
        } else {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
                ActivityCompat.requestPermissions(activity,new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE,Manifest.permission.READ_EXTERNAL_STORAGE},EXTERNAL_STORAGE_PERMISSION_REQUEST_CODE);
            }else{
                ActivityCompat.requestPermissions(activity,new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},EXTERNAL_STORAGE_PERMISSION_REQUEST_CODE);
            }
        }
    }

    public void requestPermissionForCamera(){
        if (ActivityCompat.shouldShowRequestPermissionRationale(activity, Manifest.permission.CAMERA)){
            Toast.makeText(activity, "Camera permission required. Please allow in App Settings for additional functionality.", Toast.LENGTH_LONG).show();
        } else {
            ActivityCompat.requestPermissions(activity,new String[]{Manifest.permission.CAMERA},CAMERA_PERMISSION_REQUEST_CODE);
        }
    }

    public void requestPermissionForShortCut(){
        if (ActivityCompat.shouldShowRequestPermissionRationale(activity, Manifest.permission.INSTALL_SHORTCUT)){
            Toast.makeText(activity, "Create ShortCut permission required. Please allow in App Settings for additional functionality.", Toast.LENGTH_LONG).show();
        } else {
            ActivityCompat.requestPermissions(activity,new String[]{Manifest.permission.INSTALL_SHORTCUT},SHORT_CUT_PERMISSION_REQUEST_CODE);
        }
    }
}

活动内部使用：

MarshMallowPermission marshMallowPermission = new MarshMallowPermission(MyActivity.this);

marshMallowPermission.checkPermissionForCall();

marshMallowPermission.requestPermissionForCall();

如果您有任何疑问，请在下方评论。