Question

我想仅在用户授予存储权限时才从活动中启动片段。我的主要活动布局如下所示

VerticalAlignment

现在，在主要活动开始时会显示此布局。我设置代码以获得存储权限。并希望用我的片段布局替换这个布局，但只有在授予存储权限后，它才能正常工作，我的片段正在加载一切正常，除了我的片段在授予权限之前启动。有没有办法在权限函数上设置回调方法，只有在授予权限的情况下才启动片段？

我的onCreate方法看起来像

Top

我的获取权限方法如下所示

<Border BorderThickness="1" Margin="44,135,0,0" BorderBrush="#FF000000" HorizontalAlignment="Left" VerticalAlignment="Top">
    <Image x:Name="imageHelmet" HorizontalAlignment="Left" Height="116" Margin="-1" VerticalAlignment="Top" Width="127" MouseEnter="helmet_MouseEnter"/>
</Border>

当我授予权限时，getPermission返回true，但是当应用程序首次运行时，它会在获取getPermission（）方法的结果之前启动片段，当我第二次运行应用程序时，它会显示片段布局。 / p>

Answer 1

您应该使用onRequestPermissionsResult来处理结果：

private static final int REQUEST_CODE = 404;

@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
    // Your code

    if (savedInstanceState == null) {
        tryToOpenHomeFragment();
    }
}

private void tryToOpenHomeFragment() {
    if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
        showHomeFragment();
    } else {
        ActivityCompat.requestPermissions(this,
                new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, REQUEST_CODE);
    }
}

@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults);
    if (requestCode == REQUEST_CODE) {
        if (grantResults.length == 1 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
            showHomeFragment();
        } else {
            // Permission was not granted
        }
    }
}

private void showHomeFragment() {
    HomeFragment fragment = new HomeFragment();
    getSupportFragmentManager()
            .beginTransaction()
            .replace(R.id.root_container, fragment)
            .commit();
}

Answer 2

您需要做的是：授予权限后，打开。

@Override
public void onRequestPermissionsResult(int requestCode,
    String permissions[], int[] grantResults) {
switch (requestCode) {
    case READ_EXTERNAL_STORAGE: {
        // If request is cancelled, the result arrays are empty.
        if (grantResults.length > 0
            && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
            // permission was granted
            HomeFragment fragment = new HomeFragment();
            FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
            transaction.replace(R.id.root_container, fragment).commit();
        } else {

            // permission denied, boo! Disable the
            // functionality that depends on this permission.

        }
        return;
    }
}

按照授予检查权限的https://developer.android.com/training/permissions/requesting上的示例进行操作。

获得许可后开始片段

2 个答案: