我必须实现相机的动态权限。有三种可能的情况:允许2。否认,3。别再问了。

 @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {

    for (String permission : permissions) {
        if (ActivityCompat.shouldShowRequestPermissionRationale(getActivity(), permission)) {
            //denied
            Log.e("denied", permission);
        } else {
            if (ActivityCompat.checkSelfPermission(getActivity(), permission) == PackageManager.PERMISSION_GRANTED) {
                //allowed
                Log.e("allowed", permission);
            } else {
                //set to never ask again
                Log.e("set to never ask again", permission);
                //do something here.
            }
        }
    }
    if (requestCode != MaterialBarcodeScanner.RC_HANDLE_CAMERA_PERM) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        return;
    }
    if (grantResults.length != 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
        mScannerView.setResultHandler(this);
        mScannerView.startCamera(mCameraId);
        mScannerView.setFlash(mFlash);
        mScannerView.setAutoFocus(mAutoFocus);
        return;
    } else {
        //set to never ask again
        Log.e("set to never ask again", permissions[0]);
    }
    DialogInterface.OnClickListener listener = new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int id) {
            dialog.cancel();
        }
    };
    AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
    builder.setTitle("Error")
            .setMessage(R.string.no_camera_permission)
            .setPositiveButton(android.R.string.ok, listener)
            .show();


}

private void insertDummyContactWrapper() {
        int hasWriteContactsPermission = checkSelfPermission(Manifest.permission.CAMERA);
        if (hasWriteContactsPermission != PackageManager.PERMISSION_GRANTED) {
            requestPermissions(new String[]{Manifest.permission.CAMERA},
                    REQUEST_CODE_ASK_PERMISSIONS);
            return;
        }
        mScannerView.setResultHandler(this);
        mScannerView.startCamera(mCameraId);
        mScannerView.setFlash(mFlash);
        mScannerView.setAutoFocus(mAutoFocus);
    }

private int checkSelfPermission(String camera) {
    if (ContextCompat.checkSelfPermission(getActivity(), Manifest.permission.CAMERA)
            != PackageManager.PERMISSION_GRANTED) {
        return REQUEST_CODE_ASK_PERMISSIONS;
    } else {
        return REQUEST_NOT_CODE_ASK_PERMISSIONS;
    }
}

可能对某人有用:——

我注意到的是，如果我们在onRequestPermissionsResult()回调方法中检查shouldshowrequestpermissionration理()标志，它只显示两种状态。

状态1:-返回true:——任何时候用户单击Deny permissions(包括第一次)。

状态2:-返回false:-如果用户选择“永不再问”。

详细工作实例链接

这里有一个很好的和简单的方法来检查当前的权限状态:

    @Retention(RetentionPolicy.SOURCE)
    @IntDef({GRANTED, DENIED, BLOCKED_OR_NEVER_ASKED })
    public @interface PermissionStatus {}

    public static final int GRANTED = 0;
    public static final int DENIED = 1;
    public static final int BLOCKED_OR_NEVER_ASKED = 2;

    @PermissionStatus 
    public static int getPermissionStatus(Activity activity, String androidPermissionName) {
        if(ContextCompat.checkSelfPermission(activity, androidPermissionName) != PackageManager.PERMISSION_GRANTED) {
            if(!ActivityCompat.shouldShowRequestPermissionRationale(activity, androidPermissionName)){
                return BLOCKED_OR_NEVER_ASKED;
            }
            return DENIED;
        }
        return GRANTED;
    }

警告:在用户通过用户提示接受/拒绝权限之前，在第一个应用程序启动时返回BLOCKED_OR_NEVER_ASKED(在sdk 23+设备上)

更新:

Android支持库现在似乎也有一个非常类似的类Android .support.v4.content。PermissionChecker，包含checkSelfPermission()，返回:

public static final int PERMISSION_GRANTED = 0;
public static final int PERMISSION_DENIED = -1;
public static final int PERMISSION_DENIED_APP_OP = -2;

我有点晚了，我也遇到过类似的问题。解决此问题如下

假设您需要位置权限

请求权限启动器

private final ActivityResultLauncher<String> requestPermissionLauncher =
      registerForActivityResult(
          new RequestPermission(),
          isGranted -> {
            if (isGranted) {
              // Permission is granted go ahead
            } else {
              shouldShowRequestPermissionRationale();
            }
          });

权限检查

  private boolean hasPermissions() {
        if (checkSelfPermission(requireActivity(), ACCESS_FINE_LOCATION) == PERMISSION_GRANTED) {
          // Permission is granted go ahead
        } else {
          requestPermissionLauncher.launch(ACCESS_FINE_LOCATION);
        }
      }

检查是否需要显示权限理性/自定义对话来教育用户

private void shouldShowRequestPermissionRationale() {
        if (!shouldShowRequestPermissionRationale(ACCESS_FINE_LOCATION)) {
          // need to show permission rational custom dialog.
        } 
    }

一旦用户标记了“不要再问”，该问题就不能再次显示。 但是可以向用户解释，他之前拒绝了权限，必须在设置中授予权限。并参考他的设置，使用以下代码:

@Override
public void onRequestPermissionsResult(int permsRequestCode, String[] permissions, int[] grantResults) {

    if (grantResults.length > 0
            && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
        // now, you have permission go ahead
        // TODO: something

    } else {

        if (ActivityCompat.shouldShowRequestPermissionRationale(MainActivity.this,
                Manifest.permission.READ_CALL_LOG)) {
            // now, user has denied permission (but not permanently!)

        } else {

            // now, user has denied permission permanently!

            Snackbar snackbar = Snackbar.make(findViewById(android.R.id.content), "You have previously declined this permission.\n" +
                "You must approve this permission in \"Permissions\" in the app settings on your device.", Snackbar.LENGTH_LONG).setAction("Settings", new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                startActivity(new Intent(android.provider.Settings.ACTION_APPLICATION_DETAILS_SETTINGS, Uri.parse("package:" + BuildConfig.APPLICATION_ID)));

            }
        });
        View snackbarView = snackbar.getView();
        TextView textView = (TextView) snackbarView.findViewById(android.support.design.R.id.snackbar_text);
        textView.setMaxLines(5);  //Or as much as you need
        snackbar.show();

        }

    }
    return;
}

我在Android m中写了一个权限请求的简写，这段代码还处理了对旧Android版本的向后兼容性。

所有丑陋的代码都被提取到一个片段中，该片段将自己附加到请求权限的活动上。PermissionRequestManager的使用方法如下:

new PermissionRequestManager()
        // We need a AppCompatActivity here, if you are not using support libraries you will have to slightly change 
        // the PermissionReuqestManager class
        .withActivity(this)

        // List all permissions you need
        .withPermissions(android.Manifest.permission.CALL_PHONE, android.Manifest.permission.READ_CALENDAR)

        // This Runnable is called whenever the request was successfull
        .withSuccessHandler(new Runnable() {
            @Override
            public void run() {
                // Do something with your permissions!
                // This is called after the user has granted all 
                // permissions, we are one a older platform where 
                // the user does not need to grant permissions 
                // manually, or all permissions are already granted

            }
        })

        // Optional, called when the user did not grant all permissions
        .withFailureHandler(new Runnable() {
            @Override
            public void run() {
                // This is called if the user has rejected one or all of the requested permissions
                L.e(this.getClass().getSimpleName(), "Unable to request permission");

            }
        })

        // After calling this, the user is prompted to grant the rights
        .request();

来看看:https://gist.github.com/crysxd/385b57d74045a8bd67c4110c34ab74aa