Android检查权限

Question

我正在permissions 23中开发我的项目，其中新引入了应用程序权限。在一些指南中，他们使用下面的代码读取电话状态，是否授予了权限。

if (ContextCompat.checkSelfPermission(serviceContext, Manifest.permission.READ_PHONE_STATE) == PackageManager.PERMISSION_GRANTED) {
    //Read Phone state
   }else{
}

但我正在直接访问checkSelfPermission，如下所示

if(serviceContext.checkSelfPermission(Manifest.permission.READ_PHONE_STATE) == PackageManager.PERMISSION_GRANTED) {
      //Read Phone state
   }else{
}

它很好用。我的问题是，上面这些codes?.which之间有什么区别，是检查许可是否被授予的正确方式吗？

Answer 1

我的问题是，以上这些代码之间有什么区别？

没有，在API 23(+)设备上。

然而，运行较旧版本安卓的设备在尝试直接调用context.checkSelfPermission()时会产生错误。此方法直到API 23才可用。

ContextCompat还提供了一种向后兼容的方式来在旧API上运行checkSelfPermission()。如果您查看实现，您将看到它通过使用应用程序自己的流程参数将调用委托给checkPermission()来实现这一点。checkPermission()自第一个API发布以来就已经可用，因此它将全面运行。

public static int checkSelfPermission(@NonNull Context context, @NonNull String permission) {
    if (permission == null) {
        throw new IllegalArgumentException("permission is null");
    }

    return context.checkPermission(permission, android.os.Process.myPid(), Process.myUid());
}

哪一种检查批准许可的方法是正确的？

因此，要回答这个问题:如果您只支持运行Android 'Marshmallow‘6.0及更新版本的设备，那么您可以使用任何一种方法。但是，由于更有可能您也希望支持一些旧版本的Android，所以使用

Answer 2

在官方和近期方式上编写代码，以便在下面使用的所有设备中支持

请求需要的权限

 // Here, thisActivity is the current activity
    if (ContextCompat.checkSelfPermission(thisActivity,
                    Manifest.permission.READ_CONTACTS)
            != PackageManager.PERMISSION_GRANTED) {

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

            // Show an expanation 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(thisActivity,
                    new String[]{Manifest.permission.READ_CONTACTS},
                    MY_PERMISSIONS_REQUEST_READ_CONTACTS);

            // MY_PERMISSIONS_REQUEST_READ_CONTACTS is an
            // app-defined int constant. The callback method gets the
            // result of the request.
        }
    }

处理权限请求响应

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

                // permission was granted, yay! Do the
                // contacts-related task you need to do.

            } else {

                // 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 3

另一种解决办法是：

//Requesting permission
private void requestStoragePermission(){

    if (ActivityCompat.shouldShowRequestPermissionRationale(this,Manifest.permission.READ_EXTERNAL_STORAGE)){
        //If the user has denied the permission previously your code will come to this block
        //Here you can explain why you need this permission
        //Explain here why you need this permission
    }

    //And finally ask for the permission
    ActivityCompat.requestPermissions(this,new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},STORAGE_PERMISSION_CODE);
}

//This method will be called when the user will tap on allow or deny
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {

    //Checking the request code of our request
    if(requestCode == STORAGE_PERMISSION_CODE){

        //If permission is granted
        if(grantResults.length >0 && grantResults[0] == PackageManager.PERMISSION_GRANTED){

            //Displaying a toast
            Toast.makeText(this,"Permission granted now you can read the storage",Toast.LENGTH_LONG).show();
        }else{
            //Displaying another toast if permission is not granted
            Toast.makeText(this,"Oops you just denied the permission",Toast.LENGTH_LONG).show();
        }
    }
}