Android O限制第三方应用进行wifi扫描

第三方app发送调用wifimanager.startscan发送不下去,因为:

@Override
    public void startScan(ScanSettings settings, WorkSource workSource, String packageName) {
        enforceChangePermission();

        mLog.info("startScan uid=%").c(Binder.getCallingUid()).flush();
        // Check and throttle background apps for wifi scan.
        if (isRequestFromBackground(packageName)) {
            long lastScanMs = mLastScanTimestamps.getOrDefault(packageName, 0L);
            long elapsedRealtime = mClock.getElapsedSinceBootMillis();

            if (lastScanMs != 0 && (elapsedRealtime - lastScanMs) < mBackgroundThrottleInterval) {
                sendFailedScanBroadcast();
                return;
            }
            // Proceed with the scan request and record the time.
            mLastScanTimestamps.put(packageName, elapsedRealtime);
        }

        ...
// Check if the request comes from background.
    private boolean isRequestFromBackground(String packageName) {
        // Requests from system or wifi are not background.
        if (Binder.getCallingUid() == Process.SYSTEM_UID
                || Binder.getCallingUid() == Process.WIFI_UID) {
            return false;
        }
        mAppOps.checkPackage(Binder.getCallingUid(), packageName);
        if (mBackgroundThrottlePackageWhitelist.contains(packageName)) {
            return false;
        }

        // getPackageImportance requires PACKAGE_USAGE_STATS permission, so clearing the incoming
        // identify so the permission check can be done on system process where wifi runs in.
        long callingIdentity = Binder.clearCallingIdentity();
        try {
            return mActivityManager.getPackageImportance(packageName)
                    > BACKGROUND_IMPORTANCE_CUTOFF;
        } finally {
            Binder.restoreCallingIdentity(callingIdentity);
        }
    }

这里return true,然后就会调用13行的sendFailedScanBroadcast,发送SCAN_RESULTS_AVAILABLE_ACTION广播并携带wifimanager.EXTRA_RESULTS_UPDATED为false的消息

// Send a failed scan broadcast to indicate the current scan request failed.
    private void sendFailedScanBroadcast() {
        // clear calling identity to send broadcast
        long callingIdentity = Binder.clearCallingIdentity();
        try {
            Intent intent = new Intent(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION);
            intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT);
            intent.putExtra(WifiManager.EXTRA_RESULTS_UPDATED, false);
            mContext.sendBroadcastAsUser(intent, UserHandle.ALL);
        } finally {
            // restore calling identity
            Binder.restoreCallingIdentity(callingIdentity);
        }

    }

总结就是Android O限制第三方应用进行wifi扫描