Bluetooth LE 扫描在后台失败 - 权限

Question

以下代码在我的 Nexus 9 运行 Android 5.1.1（Build LMY48M）上运行良好，但在 Nexus 9 运行 Android 6.0（构建 MPA44l）

List<ScanFilter> filters = new ArrayList<ScanFilter>();
ScanSettings settings = (new ScanSettings.Builder().setScanMode(ScanSettings.SCAN_MODE_LOW_POWER)).build();
ScanFilter.Builder builder = new ScanFilter.Builder();
builder.setManufacturerData((int) 0x0118, new byte[]{(byte) 0xbe, (byte) 0xac}, new byte[]{(byte) 0xff, (byte)0xff});
ScanFilter scanFilter = builder.build();
filters.add(scanFilter);
mBluetoothLeScanner.startScan(filters, settings, new ScanCallback() {
  ...
});

在 Android 5.x，上面的代码在看到与扫描过滤器匹配的制造商广告时产生回调。（请参阅下面的示例 Logcat 输出。）在带有 MPA44l 的 Nexus 9 上，没有收到任何回调。如果您注释掉扫描过滤器，则在 Nexus 9 上会成功接收到回调。

09-22 00:07:28.050    1748-1796/org.altbeacon.beaconreference D/BluetoothLeScanner﹕ onScanResult() - ScanResult{mDevice=00:07:80:03:89:8C, mScanRecord=ScanRecord [mAdvertiseFlags=6, mServiceUuids=null, mManufacturerSpecificData={280=[-66, -84, 47, 35, 68, 84, -49, 109, 74, 15, -83, -14, -12, -111, 27, -87, -1, -90, 0, 1, 0, 1, -66, 0]}, mServiceData={}, mTxPowerLevel=-2147483648, mDeviceName=null], mRssi=-64, mTimestampNanos=61272522487278}

有人见过 ScanFilters 在 Android M 上工作吗？

Answer 1

问题不是扫描过滤器，而是后台权限。

Android 10-11:

为了在后台检测 BLE 设备，您必须在清单中具有多个权限。将以下内容放入您的 AndroidManifest.xml:

<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.ACCESS_BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.ACCESS_BACKGROUND_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

然后将如下代码添加到您的 Activity 以动态地向用户请求这些权限：

    private static final int PERMISSION_REQUEST_FINE_LOCATION = 1;
    private static final int PERMISSION_REQUEST_BACKGROUND_LOCATION = 2;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ...



        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            if (this.checkSelfPermission(Manifest.permission.ACCESS_FINE_LOCATION)
                    == PackageManager.PERMISSION_GRANTED) {
                if (this.checkSelfPermission(Manifest.permission.ACCESS_BACKGROUND_LOCATION)
                        != PackageManager.PERMISSION_GRANTED) {
                    if (this.shouldShowRequestPermissionRationale(Manifest.permission.ACCESS_BACKGROUND_LOCATION)) {
                        final AlertDialog.Builder builder = new AlertDialog.Builder(this);
                        builder.setTitle("This app needs background location access");
                        builder.setMessage("Please grant location access so this app can detect beacons in the background.");
                        builder.setPositiveButton(android.R.string.ok, null);
                        builder.setOnDismissListener(new DialogInterface.OnDismissListener() {

                            @TargetApi(23)
                            @Override
                            public void onDismiss(DialogInterface dialog) {
                                requestPermissions(new String[]{Manifest.permission.ACCESS_BACKGROUND_LOCATION},
                                        PERMISSION_REQUEST_BACKGROUND_LOCATION);
                            }

                        });
                        builder.show();
                    }
                    else {
                        final AlertDialog.Builder builder = new AlertDialog.Builder(this);
                        builder.setTitle("Functionality limited");
                        builder.setMessage("Since background location access has not been granted, this app will not be able to discover beacons in the background.  Please go to Settings -> Applications -> Permissions and grant background location access to this app.");
                        builder.setPositiveButton(android.R.string.ok, null);
                        builder.setOnDismissListener(new DialogInterface.OnDismissListener() {

                            @Override
                            public void onDismiss(DialogInterface dialog) {
                            }

                        });
                        builder.show();
                    }

                }
            } else {
                if (!this.shouldShowRequestPermissionRationale(Manifest.permission.ACCESS_FINE_LOCATION)) {
                    requestPermissions(new String[]{Manifest.permission.ACCESS_FINE_LOCATION,
                                    Manifest.permission.ACCESS_BACKGROUND_LOCATION},
                            PERMISSION_REQUEST_FINE_LOCATION);
                }
                else {
                    final AlertDialog.Builder builder = new AlertDialog.Builder(this);
                    builder.setTitle("Functionality limited");
                    builder.setMessage("Since location access has not been granted, this app will not be able to discover beacons.  Please go to Settings -> Applications -> Permissions and grant location access to this app.");
                    builder.setPositiveButton(android.R.string.ok, null);
                    builder.setOnDismissListener(new DialogInterface.OnDismissListener() {

                        @Override
                        public void onDismiss(DialogInterface dialog) {
                        }

                    });
                    builder.show();
                }

            }
        }
    }

当您提示用户位置权限时，OS 对话框会为他们提供将该权限请求降级为“仅在使用应用程序时允许”与“始终允许”的选项。如果用户选择第一个选项，您将不会在后台进行检测，即使上面的所有其他设置都已设置。

在 Android 11 上，事情变得更加复杂，因为 OS 为权限请求提供了“仅这一次”的另一个选项。如果您的应用程序以 SDK 30 (Android 11) 为目标，它甚至不会为用户提供“始终允许”的选项，用户将不得不转到“设置”作为一个单独的步骤来打开所有时间访问。有关此在 Android 11.

上的工作方式的更多详细信息，请参阅 here

有关权限提示演变的更广泛讨论，请参阅我的博客 post here。

之前 Android 10:

从 Android M 开始，除非应用程序具有以下两种权限之一，否则后台蓝牙 LE 扫描将被阻止：

android.permission.ACCESS_COARSE_LOCATION
android.permission.ACCESS_FINE_LOCATION

我正在测试的应用程序没有请求这些权限中的任何一个，因此它在 Android M 上无法在后台运行（唯一一次扫描过滤器处于活动状态）。添加第一个解决了问题。

我意识到这是问题所在，因为我在 Logcat 中看到以下行：

09-22 22:35:20.152  5158  5254 E BluetoothUtils: Permission denial: Need ACCESS_COARSE_LOCATION or ACCESS_FINE_LOCATION permission to get scan results

详情请看这里：https://code.google.com/p/android-developer-preview/issues/detail?id=2964

Answer 2

我在连接蓝牙的应用程序中遇到了类似的问题。不是 LE ScanFilter，但这是一个权限问题，就像 OP 一样。

根本原因是从 SDK 23 开始，您需要使用 Activity 的 requestPermissions() 方法在运行时提示用户权限。

这对我有用：

将以下两行之一添加到 AndroidManifest.xml，在根节点内：

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

在您的 Activity 中，在尝试连接到蓝牙之前，调用 Activity 的 requestPermissions() 方法，这会打开一个系统对话框提示用户输入许可。权限对话框在不同的线程中打开，所以在尝试连接蓝牙之前一定要等待结果。
覆盖 Activity 的 onRequestPermissionsResult() 来处理结果。如果用户拒绝授予权限，此方法实际上只需要做一些事情，告诉用户该应用无法进行蓝牙 activity.

This blog post 有一些示例代码使用 AlertDialogs 告诉用户发生了什么。这是一个很好的起点，但也有一些缺点：

它不处理等待 requestPermissions() 线程完成
包含对 requestPermissions() 的调用的 AlertDialog 对我来说似乎无关紧要。只调用 requestPermissions() 就足够了。

Answer 3

添加位置权限以及 BLE

<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

复制粘贴此方法以请求和授予位置权限

  @Override
    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
        switch (requestCode) {
            case REQUEST_CODE_ASK_MULTIPLE_PERMISSIONS: {
                Map<String, Integer> perms = new HashMap<String, Integer>();
                // Initial
                perms.put(Manifest.permission.ACCESS_FINE_LOCATION, PackageManager.PERMISSION_GRANTED);


                // Fill with results
                for (int i = 0; i < permissions.length; i++)
                    perms.put(permissions[i], grantResults[i]);

                // Check for ACCESS_FINE_LOCATION
                if (perms.get(Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED

                        ) {
                    // All Permissions Granted

                    // Permission Denied
                    Toast.makeText(ScanningActivity.this, "All Permission GRANTED !! Thank You :)", Toast.LENGTH_SHORT)
                            .show();


                } else {
                    // Permission Denied
                    Toast.makeText(ScanningActivity.this, "One or More Permissions are DENIED Exiting App :(", Toast.LENGTH_SHORT)
                            .show();

                    finish();
                }
            }
            break;
            default:
                super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        }
    }


    @TargetApi(Build.VERSION_CODES.M)
    private void fuckMarshMallow() {
        List<String> permissionsNeeded = new ArrayList<String>();

        final List<String> permissionsList = new ArrayList<String>();
        if (!addPermission(permissionsList, Manifest.permission.ACCESS_FINE_LOCATION))
            permissionsNeeded.add("Show Location");

        if (permissionsList.size() > 0) {
            if (permissionsNeeded.size() > 0) {

                // Need Rationale
                String message = "App need access to " + permissionsNeeded.get(0);

                for (int i = 1; i < permissionsNeeded.size(); i++)
                    message = message + ", " + permissionsNeeded.get(i);

                showMessageOKCancel(message,
                        new DialogInterface.OnClickListener() {

                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                                requestPermissions(permissionsList.toArray(new String[permissionsList.size()]),
                                        REQUEST_CODE_ASK_MULTIPLE_PERMISSIONS);
                            }
                        });
                return;
            }
            requestPermissions(permissionsList.toArray(new String[permissionsList.size()]),
                    REQUEST_CODE_ASK_MULTIPLE_PERMISSIONS);
            return;
        }

        Toast.makeText(ScanningActivity.this, "No new Permission Required- Launching App .You are Awesome!!", Toast.LENGTH_SHORT)
                .show();
    }

    private void showMessageOKCancel(String message, DialogInterface.OnClickListener okListener) {
        new AlertDialog.Builder(ScanningActivity.this)
                .setMessage(message)
                .setPositiveButton("OK", okListener)
                .setNegativeButton("Cancel", null)
                .create()
                .show();
    }

    @TargetApi(Build.VERSION_CODES.M)
    private boolean addPermission(List<String> permissionsList, String permission) {

        if (checkSelfPermission(permission) != PackageManager.PERMISSION_GRANTED) {
            permissionsList.add(permission);
            // Check for Rationale Option
            if (!shouldShowRequestPermissionRationale(permission))
                return false;
        }
        return true;
    }

然后在 onCreate 检查权限

 if (Build.VERSION.SDK_INT >= 23) {
            // Marshmallow+ Permission APIs
            fuckMarshMallow();
        }

希望它能节省您的时间。

Answer 4

如果您的应用针对 Android Q，仅粗略定位是不够的，您需要使用精细定位，否则会出现此错误：

E/BluetoothUtils: Permission denial: Need ACCESS_FINE_LOCATION permission to get scan results

请参阅 https://developer.android.com/preview/privacy/camera-connectivity#fine-location-telephony-wifi-bt 了解官方来源。

Bluetooth LE 扫描在后台失败 - 权限

Bluetooth LE Scan fails in the background - permissions

android

bluetooth-lowenergy

android-bluetooth

android-6.0-marshmallow