Android WifiManager getScanResult 抱怨需要 ACCESS_COARSE_LOCATION 或 ACCESS_FINE_LOCATION 权限，尽管声明了权限

Question

我正在开发一个应用来检查 Wifi 盒子。

我在 wifiManager.getScanResults() 处收到错误“java.lang.SecurityException：需要 ACCESS_COARSE_LOCATION 或 ACCESS_FINE_LOCATION 权限才能获取扫描结果”，即使我已经声明了这些权限。

主要活动

public class MainActivity extends AppCompatActivity {

WifiManager wifiManager;
String[] wifis;
WifiReceiver wifiReceiver;

ListView wifiListView;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    wifiListView = (ListView) findViewById(R.id.wifi_list);

    wifiManager = (WifiManager) getSystemService(Context.WIFI_SERVICE);
    wifiReceiver = new WifiReceiver();
    wifiManager.startScan();
}

protected void onPause() {
    unregisterReceiver(wifiReceiver);
    super.onPause();
}

protected void onResume() {
    registerReceiver(wifiReceiver, new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));
    super.onResume();
}

private class WifiReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        List<ScanResult> wifiScanList = wifiManager.getScanResults();
        wifis = new String[wifiScanList.size()];

        for (int i = 0; i < wifiScanList.size(); i++) {
            wifis[i] = wifiScanList.get(i).toString();
        }

        wifiListView.setAdapter(new ArrayAdapter<>(getApplicationContext(), android.R.layout.simple_list_item_1, wifis));
    }
}

清单

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.sample">

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

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

我使用的是 SDK 6.0

我观察到类似的question，但由于我已经声明了许可，因此解决方案不适用。

有人知道可能是什么问题吗？谢谢。

Answer 1

在Android M中，每次使用前都需要向用户询问PermissionModel中定义为危险的权限，如下：

private boolean mayRequestLocation() {
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
            return true;
        }
        if (checkSelfPermission(ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED) {
            return true;
        }
        if (shouldShowRequestPermissionRationale(ACCESS_FINE_LOCATION)) {
            Snackbar.make(mView, R.string.permission_rationale, Snackbar.LENGTH_INDEFINITE)
                    .setAction(android.R.string.ok, new View.OnClickListener() {
                        @Override
                        @TargetApi(Build.VERSION_CODES.M)
                        public void onClick(View v) {
                            requestPermissions(new String[]{ACCESS_FINE_LOCATION}, REQUEST_FINE_LOCATION);
                        }
                    });
        } else {
            requestPermissions(new String[]{ACCESS_FINE_LOCATION}, REQUEST_FINE_LOCATION);
        }
        return false;
    }

将此添加到您的活动中：

private static final int REQUEST_FINE_LOCATION=0

并在运行时加载它：

loadPermissions(Manifest.permission.ACCESS_FINE_LOCATION,REQUEST_FINE_LOCATION);

要评估您的权限请求的结果，您可以重写 onRequestPermissionsResult 方法：

@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
    switch (requestCode) {
        case REQUEST_FINE_LOCATION: {
            // If request is cancelled, the result arrays are empty.
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                // The requested permission is granted.
            }
            else{
                // The user disallowed the requested permission.
            }
            return;
        }

}

Answer 2

MADAO is right：你应该打开GPS来获取WIFI接入点列表。

但我不确定 PEERS_MAC_ADDRESS。如果您查看the source code（第 957 行）：

/**
 * Return the results of the most recent access point scan, in the form of
 * a list of {@link ScanResult} objects.
 * @return the list of results
 */
public List<ScanResult> getScanResults(String callingPackage) {
    enforceAccessPermission();
    int userId = UserHandle.getCallingUserId();
    int uid = Binder.getCallingUid();
    boolean canReadPeerMacAddresses = checkPeersMacAddress();
    boolean isActiveNetworkScorer =
            NetworkScorerAppManager.isCallerActiveScorer(mContext, uid);
    boolean hasInteractUsersFull = checkInteractAcrossUsersFull();
    long ident = Binder.clearCallingIdentity();
    try {
        if (!canReadPeerMacAddresses && !isActiveNetworkScorer
                && !isLocationEnabled()) {
            return new ArrayList<ScanResult>();
        }
        if (!canReadPeerMacAddresses && !isActiveNetworkScorer
                && !checkCallerCanAccessScanResults(callingPackage, uid)) {
            return new ArrayList<ScanResult>();
        }
        if (mAppOps.noteOp(AppOpsManager.OP_WIFI_SCAN, uid, callingPackage)
                != AppOpsManager.MODE_ALLOWED) {
            return new ArrayList<ScanResult>();
        }
        if (!isCurrentProfile(userId) && !hasInteractUsersFull) {
            return new ArrayList<ScanResult>();
        }
        return mWifiStateMachine.syncGetScanResultsList();
    } finally {
        Binder.restoreCallingIdentity(ident);
    }
}

第一个if 正在检查canReadPeerMacAddresses，checkPeersMacAddress() 的代码是：

/**
 * Returns true if the caller holds PEERS_MAC_ADDRESS.
 */
private boolean checkPeersMacAddress() {
    return mContext.checkCallingOrSelfPermission(
            android.Manifest.permission.PEERS_MAC_ADDRESS) == PackageManager.PERMISSION_GRANTED;
}

如果您添加权限，您可以绕过if (!canReadPeerMacAddresses && !isActiveNetworkScorer && !isLocationEnabled()) {。我已经测试过，但我无法通过仅使用权限和禁用位置来获取 WIFI MAC 列表。

Answer 3

ACCESS_FINE_LOCATION 或 ACCESS_COARSE_LOCATION 是必需的。要获得有效结果，您还必须打开 GPS 或获得PEERS_MAC_ADDRESS 权限，例如Setting。