在用户输入之前 Android 权限请求运行代码出现问题

Question

我有以下辅助方法来检查权限：

private boolean canAccessLocation() {
        return(hasPermission(Manifest.permission.ACCESS_FINE_LOCATION));
    }
private boolean hasPermission(String perm) {
        return(PackageManager.PERMISSION_GRANTED==checkCallingOrSelfPermission(perm));
    }

我有一个请求方法来提示用户访问他们的位置

public void requestLocationPermissions(){
        if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.ACCESS_COARSE_LOCATION) || ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.ACCESS_FINE_LOCATION)) {
            Log.d("permissions",
                    "Displaying contacts permission rationale to provide additional context.");
            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION, Manifest.permission.ACCESS_COARSE_LOCATION},
                    REQUEST_LOCATION);

        } else {
            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION, Manifest.permission.ACCESS_COARSE_LOCATION},
                    REQUEST_LOCATION);
        }
    }

在需要位置权限的地方，我写

if(!canAccessLocation()){
            requestLocationPermissions();
        } else {

}
startActivity(new Intent(MyActivity.this, MyOtherActivity.class));

我遇到的问题是，在向用户显示允许或拒绝权限的对话框之前，新的 activity 是通过意图启动的。因此，如果我在下一个 activity 中有代码要求用户授予或拒绝权限，它将崩溃，然后然后询问用户是否要授予权限。我很难让 API 23 权限系统在此应用程序上正常工作，我真的需要一些帮助。

所以我的问题是：在用户选择是否拒绝或允许权限之前，如何阻止后续代码行的执行？

Answer 1

如果发布的片段正是您在项目中尝试的片段，那么解决方案很简单 :D

if(!canAccessLocation()){
    requestLocationPermissions();
  } else {
//start only if permission is granted
startActivity(new Intent(MyActivity.this, MyOtherActivity.class)); 
}

Answer 2

您确实需要在请求权限的 Activity 中实现此回调

void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults);

在该回调中，只需验证 requestCode 是否是您请求的，如果 grantResults[0] == PackageManager.PERMISSION_GRANTED，如果是，则在授予权限后执行您需要执行的操作，例如生成一个新的 [=20] =].

此外，如果 ActivityCompat.shouldShowRequestPermissionRationale 调用 returns 为真，您应该向用户显示一条提示，说明请求权限的理由。一旦用户按下 'Ok'，您将再次请求权限。

Answer 3

我为此苦苦挣扎了几个小时，所以我只是想把它放在那里以防它对某人有用。

我改编了以下代码： https://developer.android.com/training/permissions/requesting.html

在我的例子中，应用程序需要请求多个 ('dangerous') 权限。我会在应用程序启动时执行此操作，然后再显示启动画面。

P.S。我应该提到我没有运气同时请求所有权限，因此递归。希望这是可能的，并且有人可以解决这个问题。另外，我已经注释掉了 'Should we show an explanation' 块。下面的逻辑不适合这种行为，但我把它留给了后代，因为它来自上面的 link。

package a.dangerous.app;

import android.Manifest;
import android.app.Activity;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;

public class AskMultiplePermsThenSpashActivity extends Activity  {

    static final String[] _requestPermissions = {
            Manifest.permission.WRITE_EXTERNAL_STORAGE,
            Manifest.permission.READ_EXTERNAL_STORAGE,
            Manifest.permission.READ_SMS,
            Manifest.permission.READ_CONTACTS,
            Manifest.permission.WRITE_CONTACTS
    };

    @Override
    protected void onStart() {
        super.onStart();

        this.checkPermissions(0);   //start at zero, of course
    }

    private void checkPermissions(int permissionIndex) {
        if(permissionIndex >= _requestPermissions.length) {
            //i.e. we have requested all permissions, so show the splash screen
            this.showSplash();
        }
        else {
            this.askForPermission(_requestPermissions[permissionIndex], permissionIndex);
        }
    }

    private void askForPermission(String permission, int permissionIndex) {
        if (ContextCompat.checkSelfPermission(
                this,
                permission)
                != PackageManager.PERMISSION_GRANTED) {

            // Should we show an explanation?
            //  if (ActivityCompat.shouldShowRequestPermissionRationale(this, permission)) {

                // 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.

            //} else {

            // No explanation needed, we can request the permission.

            ActivityCompat.requestPermissions(
                    this,
                    new String[]{permission},
                    permissionIndex //permissionIndex will become the requestCode on callback
            );
        }
        else {
            this.checkPermissions(permissionIndex+1); //check the next permission
        }
    }

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

        //Regardless of whether the permission was granted we carry on.
        //If perms have been denied then the app must cater for it

        this.checkPermissions(requestCode+1); //check the next permission
    }

    private void showSplash() {
        //(ta da)

        //once splashed, start the main activity
        this.startMainActivity();
    }

    private void startMainActivity() {
        Intent mainIntent = new Intent(
                this,
                MainActivity.class
        );
        mainIntent.addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);

        this.startActivity(mainIntent);

        this.finish();
    }
}

在用户输入之前 Android 权限请求运行代码出现问题

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在用户输入之前 Android 权限请求运行代码出现问题