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Android 8 wifi 扫描时间间隔

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【Android 8 wifi 扫描时间间隔】一万年来谁著史，三千里外欲封侯。这篇文章主要讲述Android 8 wifi 扫描时间间隔相关的知识，希望能为你提供帮助。

wifi setting界面扫描时间间隔：10s 不在wifi setting界面，扫描时间间隔，最小20s，然后按找2倍的间隔进行递增，40s,60s..., 最大160s PNO 即Preferred Network Offload，用于系统在休眠的时候连接WiFi 1. wifi setting界面 packagesappsSettingssrccomandroidsettingswifiWifiSettings.java public void onStart() { mWifiTracker.startTracking(); frameworksasepackagesSettingsLibsrccomandroidsettingslibwifiWifiTracker.java public void startTracking() { synchronized (mLock) { registerScoreCache(); // 是否显示wifi评分的UI mNetworkScoringUiEnabled = Settings.Global.getInt( mContext.getContentResolver(), Settings.Global.NETWORK_SCORING_UI_ENABLED, 0) == 1; // 是否显示wifi速度 mMaxSpeedLabelScoreCacheAge = Settings.Global.getLong( mContext.getContentResolver(), Settings.Global.SPEED_LABEL_CACHE_EVICTION_AGE_MILLIS, DEFAULT_MAX_CACHED_SCORE_AGE_MILLIS); resumeScanning(); if (!mRegistered) { mContext.registerReceiver(mReceiver, mFilter); // NetworkCallback objects cannot be reused. http://b/20701525 . mNetworkCallback = new WifiTrackerNetworkCallback(); mConnectivityManager.registerNetworkCallback(mNetworkRequest, mNetworkCallback); mRegistered = true; } }} 扫描服务 public void resumeScanning() { if (mScanner == null) { mScanner = new Scanner(); }mWorkHandler.sendEmptyMessage(WorkHandler.MSG_RESUME); if (mWifiManager.isWifiEnabled()) { mScanner.resume(); // 发送扫描消息 } }// class Scanner extends Handler { static final int MSG_SCAN = 0; private int mRetry = 0; void resume() { if (!hasMessages(MSG_SCAN)) { sendEmptyMessage(MSG_SCAN); } }void forceScan() { removeMessages(MSG_SCAN); sendEmptyMessage(MSG_SCAN); }void pause() { mRetry = 0; removeMessages(MSG_SCAN); }@VisibleForTesting boolean isScanning() { return hasMessages(MSG_SCAN); }@Override public void handleMessage(Message message) { if (message.what != MSG_SCAN) return; if (mWifiManager.startScan()) {// 启动扫描 mRetry = 0; } else if (++mRetry > = 3) { mRetry = 0; if (mContext != null) { Toast.makeText(mContext, R.string.wifi_fail_to_scan, Toast.LENGTH_LONG).show(); } return; } // 扫描界面扫描间隔。 sendEmptyMessageDelayed(MSG_SCAN, WIFI_RESCAN_INTERVAL_MS); } } //private static final int WIFI_RESCAN_INTERVAL_MS = 10 * 1000; 2. 不在wifisetting界面，亮屏情况下。 frameworksopt etwifiservicejavacomandroidserverwifiWifiConnectivityManager.javapublic void handleScreenStateChanged(boolean screenOn) { localLog(" handleScreenStateChanged: screenOn=" + screenOn); mScreenOn = screenOn; mOpenNetworkNotifier.handleScreenStateChanged(screenOn); startConnectivityScan(SCAN_ON_SCHEDULE); }private void startConnectivityScan(boolean scanImmediately) { localLog(" startConnectivityScan: screenOn=" + mScreenOn + " wifiState=" + stateToString(mWifiState) + " scanImmediately=" + scanImmediately + " wifiEnabled=" + mWifiEnabled + " wifiConnectivityManagerEnabled=" + mWifiConnectivityManagerEnabled); if (!mWifiEnabled || !mWifiConnectivityManagerEnabled) { return; }// Always stop outstanding connecivity scan if there is any stopConnectivityScan(); // Don' t start a connectivity scan while Wifi is in the transition // between connected and disconnected states. if (mWifiState != WIFI_STATE_CONNECTED & & mWifiState != WIFI_STATE_DISCONNECTED) { return; }if (mScreenOn) { startPeriodicScan(scanImmediately); } else { if (mWifiState == WIFI_STATE_DISCONNECTED & & !mPnoScanStarted) { startDisconnectedPnoScan(); } } }// Start a periodic scan when screen is on private void startPeriodicScan(boolean scanImmediately) { // 从新设置PNO扫描的时间间隔。 // 当扫描的网络，Rssi比较低时，将会进行从新扫描 mPnoScanListener.resetLowRssiNetworkRetryDelay(); // 漫游关闭时，不进行扫描 // No connectivity scan if auto roaming is disabled. if (mWifiState == WIFI_STATE_CONNECTED & & !mEnableAutoJoinWhenAssociated) { return; }// Due to b/28020168, timer based single scan will be scheduled // to provide periodic scan in an exponential backoff fashion. if (scanImmediately) { resetLastPeriodicSingleScanTimeStamp(); } mPeriodicSingleScanInterval = PERIODIC_SCAN_INTERVAL_MS; startPeriodicSingleScan(); }@VisibleForTesting public static final int PERIODIC_SCAN_INTERVAL_MS = 20 * 1000; // 20 seconds// Start a single scan and set up the interval for next single scan. private void startPeriodicSingleScan() { long currentTimeStamp = mClock.getElapsedSinceBootMillis(); if (mLastPeriodicSingleScanTimeStamp != RESET_TIME_STAMP) { long msSinceLastScan = currentTimeStamp - mLastPeriodicSingleScanTimeStamp; if (msSinceLastScan < PERIODIC_SCAN_INTERVAL_MS) { localLog(" Last periodic single scan started " + msSinceLastScan + " ms ago, defer this new scan request." ); schedulePeriodicScanTimer(PERIODIC_SCAN_INTERVAL_MS - (int) msSinceLastScan); return; } }boolean isFullBandScan = true; // 判断wifi使用率是不是比较高，比较高只进行一部分扫描 // 通过发送和接收速率判断 // If the WiFi traffic is heavy, only partial scan is initiated. if (mWifiState == WIFI_STATE_CONNECTED & & (mWifiInfo.txSuccessRate > mFullScanMaxTxRate || mWifiInfo.rxSuccessRate > mFullScanMaxRxRate)) { localLog(" No full band scan due to ongoing traffic" ); isFullBandScan = false; } // 再次判断，如果发送接收速率超过最大值，将不进行扫描。 mLastPeriodicSingleScanTimeStamp = currentTimeStamp; if (mWifiState == WIFI_STATE_CONNECTED & & (mWifiInfo.txSuccessRate > MAX_TX_PACKET_FOR_PARTIAL_SCANS || mWifiInfo.rxSuccessRate > MAX_RX_PACKET_FOR_PARTIAL_SCANS)) { Log.e(TAG," Ignore scan due to heavy traffic" ); } else { startSingleScan(isFullBandScan, WIFI_WORK_SOURCE); }schedulePeriodicScanTimer(mPeriodicSingleScanInterval); // 设置下一次扫描时间间隔，是当前的2倍。 // 最大扫描时间间隔160s // public static final int MAX_PERIODIC_SCAN_INTERVAL_MS = 160 * 1000; // 160 seconds // Set up the next scan interval in an exponential backoff fashion. mPeriodicSingleScanInterval *= 2; if (mPeriodicSingleScanInterval > MAX_PERIODIC_SCAN_INTERVAL_MS) { mPeriodicSingleScanInterval = MAX_PERIODIC_SCAN_INTERVAL_MS; } }3. pno扫描 private void startDisconnectedPnoScan() { // TODO(b/29503772): Need to change this interface.// Initialize PNO settings PnoSettings pnoSettings = new PnoSettings(); List< PnoSettings.PnoNetwork> pnoNetworkList = mConfigManager.retrievePnoNetworkList(); int listSize = pnoNetworkList.size(); if (listSize == 0) { // No saved network localLog(" No saved network for starting disconnected PNO." ); return; }pnoSettings.networkList = new PnoSettings.PnoNetwork[listSize]; pnoSettings.networkList = pnoNetworkList.toArray(pnoSettings.networkList); pnoSettings.min5GHzRssi = mMin5GHzRssi; pnoSettings.min24GHzRssi = mMin24GHzRssi; pnoSettings.initialScoreMax = mInitialScoreMax; pnoSettings.currentConnectionBonus = mCurrentConnectionBonus; pnoSettings.sameNetworkBonus = mSameNetworkBonus; pnoSettings.secureBonus = mSecureBonus; pnoSettings.band5GHzBonus = mBand5GHzBonus; // Initialize scan settings ScanSettings scanSettings = new ScanSettings(); scanSettings.band = getScanBand(); scanSettings.reportEvents = WifiScanner.REPORT_EVENT_NO_BATCH; scanSettings.numBssidsPerScan = 0; scanSettings.periodInMs = DISCONNECTED_PNO_SCAN_INTERVAL_MS; // 20smPnoScanListener.clearScanDetails(); mScanner.startDisconnectedPnoScan(scanSettings, pnoSettings, mPnoScanListener); mPnoScanStarted = true; } 待续。。。


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