android - 我如何获得 Activity ？

Question

我在运行时请求权限，对于方法 requestPermissions() 我需要通过一个 Activity 。但是，当我在 onClick() 中调用它时，我不能只通过 this。那么，我该如何通过它呢？

我需要 Activity 的地方在 onRequestPermissionsResult() 中，在 case locationPerm:

public class LoginActivity extends AppCompatActivity implements LocationListener {

    final int locationPerm = 0;
    final int cameraPerm = 1;

    Context context;
    Activity activity;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.login_nav_bar);

        context = this;


        int locationPermissionCheck = ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION);

        int cameraPermissionCheck = ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA);

        if (locationPermissionCheck != PackageManager.PERMISSION_GRANTED) {
                ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, locationPerm);
        }

        if (cameraPermissionCheck != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA}, cameraPerm);
        }
     }

    @Override
    public void onRequestPermissionsResult(int requestCode,
                                           String permissions[], int[] grantResults) {
        switch (requestCode) {
            case locationPerm: {
                // If request is cancelled, the result arrays are empty.
                if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) { // permission was granted, yay! Do the

                } else { // permission denied,
                    new AlertDialog.Builder(this)
                            .setTitle("Location Permission")
                            .setMessage("Message")
                            .setPositiveButton("Set a custom location later", new DialogInterface.OnClickListener() {
                                @Override
                                public void onClick(DialogInterface dialogInterface, int i) {
                                    ActivityCompat.requestPermissions(/* NEED ACTIVITY HERE */, new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, locationPerm);
                                }
                            })
                            .setNegativeButton("Re-Prompt Request", new DialogInterface.OnClickListener() {
                                @Override
                                public void onClick(DialogInterface dialogInterface, int i) {

                                }
                            })
                            .show();
                }
                return;
            }
            case cameraPerm: {
                if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) { // permission was granted, yay! Do the

                } else { // permission denied,

                }
                return;
            }
        }
    }

抱歉，如果这是一个简单的修复，我是 Android 应用程序开发的新手。

Answer 1

简单的回答就是“this”指的是这里的Button。为了通过 Activity ，有两种方式:

• LoginActivity.this [确定]

• getApplicationcontext() [如果要传递应用上下文]