java - 如何*正确*请求权限？

Question

我正在开发一个启动时需要 3 个权限的 Android 应用程序。我必须等到用户在对话框中做出响应，否则应用程序会崩溃，因为权限是强制性的。

请求这些权限的正确方法是什么？我编写了以下代码，但应用程序在响应第一个权限(拒绝或接受)时卡住。

这是我做的:

    String[] perms = {"Manifest.permission.READ_PHONE_STATE", "Manifest.permission.ACCESS_COARSE_LOCATION","Manifest.permission.CALL_PHONE"};

    int result1 = ContextCompat.checkSelfPermission(getApplicationContext(), Manifest.permission.READ_PHONE_STATE);
    int result2 = ContextCompat.checkSelfPermission(getApplicationContext(), Manifest.permission.ACCESS_COARSE_LOCATION);
    int result3 = ContextCompat.checkSelfPermission(getApplicationContext(), Manifest.permission.CALL_PHONE);

    if ((result1 == PackageManager.PERMISSION_GRANTED) && (result2 == PackageManager.PERMISSION_GRANTED) && (result3 == PackageManager.PERMISSION_GRANTED)) {
        onPermissionGranted();
    } else {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            requestPermissions(perms, PERMISSION_REQUEST_CODE);
        } else {
            ActivityCompat.requestPermissions(this, perms, PERMISSION_REQUEST_CODE);
        }

    }

@Override
public void onRequestPermissionsResult(int requestCode,
                                       String permissions[], int[] grantResults) {
    switch (requestCode) {
        case PERMISSION_REQUEST_CODE: {
            // If request is cancelled, the result arrays are empty.
            if (grantResults.length > 0
                    && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                onPermissionGranted();
                // permission was granted, yay! Do the
                // contacts-related task you need to do.

            } else {
                Toast.makeText(MainActivity.this, R.string.permission_required, Toast.LENGTH_LONG).show();
                // permission denied, boo! Disable the
                // functionality that depends on this permission.


            }
            return;
        }

        // other 'case' lines to check for other
        // permissions this app might request
    }
}

Answer 1

无需阻塞，无论是使用 Thread#sleep 还是使用 while 循环，因为权限请求是异步的。以下是您的 Activity 的流程:

首先，定义需要权限才能运行的逻辑:

private void onPermissionGranted() {
   //code to execute
}

然后，在 onCreate() 中，检查您是否拥有这些权限。如果这样做，请执行您的代码。如果不这样做，请请求许可:

if (ContextCompat.checkSelfPermission(this,/*permissions*/) == PackageManager.PERMISSION_GRANTED) {
    onPermissionGranted();
} else {
   ActivityCompat.requestPermissions(this, /*permissions*/, /*request_code*/); 
}

当权限状态更新后，它会调用 onRequestPermissionsResult。如果获得许可，则在此处执行操作。否则，执行其他操作(重新显示对话框或完成 Activity )。

@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
    switch (requestCode) {
        case /*our request code from before*/: {
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                onPermissionGranted();
            } else {
                Toast.makeText(this, "Permissions are required in order to run this app!", Toast.LENGTH_SHORT).show();
                finish();
            }
            return;
        }
    }
}