了解Android 6权限方法

Question

我正在尝试从Gallery中获取图像并将其设置为imageview,但在Android 6中存在一些权限问题.以下是要求许可的方法.我应该要求读外部存储还是写外部存储？

这是我到目前为止所做的:

    private static final int READ_CONTACTS_PERMISSIONS_REQUEST = 1;


    public void getPermissionToReadExternalStorage() {

    if (ContextCompat.checkSelfPermission(getActivity(), Manifest.permission.READ_EXTERNAL_STORAGE)
            != PackageManager.PERMISSION_GRANTED) {

        if (shouldShowRequestPermissionRationale(
                Manifest.permission.READ_EXTERNAL_STORAGE)) {

            requestPermissions(new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},
                    READ_CONTACTS_PERMISSIONS_REQUEST);
        }}}
    @Override
            public void onRequestPermissionsResult(int requestCode,
                                                   @NonNull String permissions[],
                                                   @NonNull int[] grantResults){
                // Make sure it's our original READ_CONTACTS request
                if (requestCode == READ_CONTACTS_PERMISSIONS_REQUEST) {
                    if (grantResults.length == 1 &&
                            grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                        Toast.makeText(getActivity(), "Read Contacts permission granted", Toast.LENGTH_SHORT).show();

                    } else {
                        Toast.makeText(getActivity(), "Read Contacts permission denied", Toast.LENGTH_SHORT).show();
                    }
                } else {
                    super.onRequestPermissionsResult(requestCode, permissions, grantResults);
                }
            }

现在我的点击监听器从图库中选择数据:

     pro.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            Intent intent = new Intent(Intent.ACTION_PICK, android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
            intent.setType("image/*");
            if (android.os.Build.VERSION.SDK_INT >= 23) {
                getPermissionToReadExternalStorage();
                if (getPermissionToReadExternalStorage () this???? <==)
                startActivityForResult(Intent.createChooser(intent, "Select Picture"), 0);
            } else {
                startActivityForResult(Intent.createChooser(intent, "Select Picture"), 0);
        }}

    });
    return v;
}

现在我想获得方法的结果,getPermissionToReadExternalStorage()这样我就可以开始为Android 6挑选图库的活动了.如何获得void类的结果？另一件事是我必须为我的应用程序要求的每个权限编写方法吗？

Answer 1

所以我完全重写了代码以请求权限.现在它支持请求多个权限并运行具有适当结果的代码.它也适用于preMarshmallow设备,因此在这种情况下您不必检查和复制代码.

首先,使用此代码创建一个Activity类(您可以扩展您需要的任何活动之王,例如AppCompatActivity):

public abstract class PermissionActivity extends AppCompatActivity {

    private final ArrayList<PermissionListener> permissionListeners = new ArrayList<>();

    @SuppressWarnings("unused")
    public void requestPermissions(int requestCode, String[] requestPermissions, PermissionListener permissionListener) {
        requestPermissions(requestCode, requestPermissions, null, permissionListener);
    }

    @SuppressWarnings("unused")
    public void requestPermissions(final int requestCode, String[] requestPermissions, String message, final PermissionListener permissionListener) {
        final int[] grantResults = new int[requestPermissions.length];

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            ArrayList<String> list_notGranted = new ArrayList<>();

            for (String requestPermission : requestPermissions)
                if (ContextCompat.checkSelfPermission(this, requestPermission) != PackageManager.PERMISSION_GRANTED)
                    list_notGranted.add(requestPermission);

            if (list_notGranted.size() > 0) {
                permissionListeners.add(permissionListener);

                requestPermissions = list_notGranted.toArray(new String[list_notGranted.size()]);

                if (message != null) {
                    boolean shouldShowRequestPermissionRationale = false;

                    for (String permission : requestPermissions)
                        if (ActivityCompat.shouldShowRequestPermissionRationale(this, permission)) {
                            shouldShowRequestPermissionRationale = true;
                            break;
                        }

                    if (shouldShowRequestPermissionRationale) {
                        final String[] f_requestPermissions = requestPermissions;

                        AlertDialog.Builder builder = new AlertDialog.Builder(this);

                        builder.setMessage(message);

                        DialogInterface.OnClickListener onClickListener = new DialogInterface.OnClickListener() {

                            @TargetApi(Build.VERSION_CODES.M)
                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                                switch (which) {
                                    case DialogInterface.BUTTON_POSITIVE:
                                        PermissionActivity.super.requestPermissions(f_requestPermissions, requestCode);
                                        break;
                                    default:
                                        for (int i = 0; i < grantResults.length; i++)
                                            grantResults[i] = PackageManager.PERMISSION_DENIED;

                                        if (permissionListener != null)
                                            permissionListener.onResult(requestCode, f_requestPermissions, grantResults);
                                        break;
                                }
                            }
                        };

                        builder.setPositiveButton("OK", onClickListener);
                        builder.setNegativeButton("Cancel", onClickListener);

                        builder.show();
                    } else {
                        super.requestPermissions(requestPermissions, requestCode);
                    }
                } else {
                    super.requestPermissions(requestPermissions, requestCode);
                }
            } else {
                for (int i = 0; i < grantResults.length; i++)
                    grantResults[i] = PackageManager.PERMISSION_GRANTED;

                if (permissionListener != null)
                    permissionListener.onResult(requestCode, requestPermissions, grantResults);
            }
        } else {
            if (permissionListener != null) {
                for (int i = 0; i < grantResults.length; i++)
                    grantResults[i] = PackageManager.PERMISSION_GRANTED;

                permissionListener.onResult(requestCode, requestPermissions, grantResults);
            }
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String permissions[], @NonNull int[] grantResults) {
        for (Iterator<PermissionListener> it = permissionListeners.iterator(); it.hasNext(); ) {
            PermissionListener permissionListener = it.next();
            if (permissionListener.onResult(requestCode, permissions, grantResults)) {
                it.remove();
            }
        }
    }

    public interface PermissionListener {

        boolean onResult(int requestCode, String[] requestPermissions, int[] grantResults);

    }
}

如果要从Fragments请求权限,请添加以下类:

public class PermissionFragment extends Fragment {

    @SuppressWarnings("unused")
    public void requestPermissions(int requestCode, String[] requestPermissions, PermissionActivity.PermissionListener permissionListener) {
        requestPermissions(requestCode, requestPermissions, null, permissionListener);
    }

    @SuppressWarnings("unused")
    public void requestPermissions(final int requestCode, String[] requestPermissions, String message, PermissionActivity.PermissionListener permissionListener) {
        ((PermissionActivity) getActivity()).requestPermissions(requestCode, requestPermissions, message, permissionListener);
    }
}

您的活动和碎片应该扩展这些类而不是标准类.

现在,您已准备好通过调用方法来请求权限:

requestPermissions(int requestCode, String[] requestPermissions, PermissionListener permissionListener)

如果应用程序需要权限才能使用,则应调用此方法并指定说明为何需要权限的消息.

requestPermissions(int requestCode, String[] requestPermissions, String message, PermissionListener permissionListener)

不要破坏默认方法,就是这样

// DON'T USE THIS ONE!
requestPermissions(String[] requestPermissions, int requestCode)
// DON'T USE THIS ONE!

以下是请求联系人的示例:

private void requestAndLoadContacts() {
    String[] permissions = new String[]{Manifest.permission.READ_CONTACTS};

    requestPermissions(REQUEST_PERMISSIONS_CONTACTS, permissions, "Read contacts permission is required for the app to work!", new PermissionListener() {

        @Override
        public boolean onResult(int requestCode, String[] requestPermissions, int[] grantResults) {
            // Check if the requestCode is ours
            if (requestCode == REQUEST_PERMISSIONS_CONTACTS) {
                // Check if the permission is correct and is granted
                if (requestPermissions[0].equals(Manifest.permission.READ_CONTACTS) && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    // Permission granted
                    // Calling a method to actually load the contacts
                    loadContacts();
                } else {
                    // Permission not granted
                    Toast.makeText(MainActivity.this, "Access denied!", Toast.LENGTH_SHORT).show();
                }

                return true;
            }

            return false;
        }
    });
}

注意:当您实现PermissionListener时,请不要忘记在requestCode是正确的时返回true,否则PermissionListener 将不会从ArrayList中删除,并且您很可能会得到一个小的内存泄漏.