Android效能專項測試之耗電量統計API
耗電量API
Android
系統中很早就有耗電量的API
,只不過一直都是隱藏的,Android
系統的設定-電池功能
就是呼叫的這個API
,該API
的核心部分是呼叫了com.android.internal.os.BatteryStatsHelper
類,利用PowerProfile
類,讀取power_profile.xml
檔案,我們一起來看看具體如何計算耗電量,首先從最新版本6.0開始看
6.0的API
原始碼
BatteryStatsHelper
其中計算耗電量的方法為490行的processAppUsage
,下來一步一步來解釋該方法。
App耗電量的計算探究
private void processAppUsage(SparseArray<UserHandle> asUsers) {
方法的引數是一個SparseArray
陣列,儲存的物件是UserHandle
,官方文件給出的解釋是,代表一個使用者,可以理解為這個類裡面儲存了使用者的相關資訊.
final boolean forAllUsers = (asUsers.get(UserHandle.USER_ALL) != null);
mStatsPeriod = mTypeBatteryRealtime;
然後給公共變數int型別的mStatsPeriod
賦值,這個值mTypeBatteryRealtime
refreshStats
方法中:
mTypeBatteryRealtime = mStats.computeBatteryRealtime(rawRealtimeUs, mStatsType);
這裡面用到了BatteryStats(mStats)
類中的computeBatteryRealtime
方法,該方法計算出此次統計電量的時間間隔。好,歪樓了,回到BatteryStatsHelper
中。
BatterySipper osSipper = null;
final SparseArray<? extends Uid> uidStats = mStats.getUidStats();
final int NU = uidStats.size();
首先建立一個BatterySipper
物件osSipper
,該物件裡面可以儲存一些後續我們要計算的值,然後通過BatteryStats
類物件mStats
來得到一個包含Uid
的物件的SparseArray
組數,然後計算了一下這個陣列的大小,儲存在變數NU中。
for (int iu = 0; iu < NU; iu++) {
final Uid u = uidStats.valueAt(iu);
final BatterySipper app = new BatterySipper(BatterySipper.DrainType.APP, u, 0);
然後for
迴圈計算每個Uid
代表的App
的耗電量,因為BatterySipper
可計算的型別有三種:應用, 系統服務, 硬體型別,所以這個地方傳入的是DrainType.APP
,還有其他可選型別如下:
public enum DrainType {
IDLE,
CELL,
PHONE,
WIFI,
BLUETOOTH,
FLASHLIGHT,
SCREEN,
APP,
USER,
UNACCOUNTED,
OVERCOUNTED,
CAMERA
}
列舉了目前可計算耗電量的模組。
mCpuPowerCalculator.calculateApp(app, u, mRawRealtime, mRawUptime, mStatsType);
mWakelockPowerCalculator.calculateApp(app, u, mRawRealtime, mRawUptime, mStatsType);
mMobileRadioPowerCalculator.calculateApp(app, u, mRawRealtime, mRawUptime, mStatsType);
mWifiPowerCalculator.calculateApp(app, u, mRawRealtime, mRawUptime, mStatsType);
mBluetoothPowerCalculator.calculateApp(app, u, mRawRealtime, mRawUptime, mStatsType);
mSensorPowerCalculator.calculateApp(app, u, mRawRealtime, mRawUptime, mStatsType);
mCameraPowerCalculator.calculateApp(app, u, mRawRealtime, mRawUptime, mStatsType);
mFlashlightPowerCalculator.calculateApp(app, u, mRawRealtime, mRawUptime, mStatsType);
其中mStatsType
的值為BatteryStats.STATS_SINCE_CHARGED
,代表了我們的計算規則是從上次充滿電後資料,還有一種規則是STATS_SINCE_UNPLUGGED
是拔掉USB線後的資料。而mRawRealtime
是當前時間,mRawUptime
是執行時間。6.0的對各個模組的消耗都交給了單獨的類去計算,這些類都繼承於PowerCalculator
抽象類:
藍芽耗電:BluetoothPowerCalculator.java
攝像頭耗電:CameraPowerCalculator.java
Cpu耗電:CpuPowerCalculator.java
手電筒耗電:FlashlightPowerCalculator.java
無線電耗電:MobileRadioPowerCalculator.java
感測器耗電:SensorPowerCalculator.java
Wakelock耗電:WakelockPowerCalculator.java
Wifi耗電:WifiPowerCalculator.java
這一部分我一會單獨拿出來挨個解釋,現在我們還是回到BatteryStatsHelper
繼續往下走
final double totalPower = app.sumPower();
BatterySipper#sumPower
方法是統計總耗電量,方法詳情如下,其中usagePowerMah
這個值有點特殊,其他的上面都講過.
/**
* Sum all the powers and store the value into `value`.
* @return the sum of all the power in this BatterySipper.
*/
public double sumPower() {
return totalPowerMah = usagePowerMah + wifiPowerMah + gpsPowerMah + cpuPowerMah +
sensorPowerMah + mobileRadioPowerMah + wakeLockPowerMah + cameraPowerMah +
flashlightPowerMah;
}
然後根據是否是DEBUG版本列印資訊,這個沒啥可說的,然後會把剛才計算的電量值新增到列表中:
// Add the app to the list if it is consuming power.
if (totalPower != 0 || u.getUid() == 0) {
//
// Add the app to the app list, WiFi, Bluetooth, etc, or into "Other Users" list.
//
final int uid = app.getUid();
final int userId = UserHandle.getUserId(uid);
if (uid == Process.WIFI_UID) {
mWifiSippers.add(app);
} else if (uid == Process.BLUETOOTH_UID) {
mBluetoothSippers.add(app);
} else if (!forAllUsers && asUsers.get(userId) == null
&& UserHandle.getAppId(uid) >= Process.FIRST_APPLICATION_UID) {
// We are told to just report this user's apps as one large entry.
List<BatterySipper> list = mUserSippers.get(userId);
if (list == null) {
list = new ArrayList<>();
mUserSippers.put(userId, list);
}
list.add(app);
} else {
mUsageList.add(app);
}
if (uid == 0) {
osSipper = app;
}
}
首先判斷totalPower
的值和當前uid號
是否符合規則,規則為總耗電量不為0或者使用者id為0.當uid
表明為WIFI或者藍芽時,新增到下面對應的列表中,一般情況下正常的應用我們直接儲存到下面的mUsageList
中就行就行,但是也有一些例外:
/**
* List of apps using power.
*/
private final List<BatterySipper> mUsageList = new ArrayList<>();
/**
* List of apps using wifi power.
*/
private final List<BatterySipper> mWifiSippers = new ArrayList<>();
/**
* List of apps using bluetooth power.
*/
private final List<BatterySipper> mBluetoothSippers = new ArrayList<>();
如果我們的系統是單使用者系統,且當前的userId
號不在我們的統計範圍內,且其程序id
號是大於Process.FIRST_APPLICATION_UID
(10000,系統分配給普通應用的其實id號),我們就要將其存放到mUserSippers
陣列中,定義如下:
private final SparseArray<List<BatterySipper>> mUserSippers = new SparseArray<>();
最後判斷uid
為0的話,代表是Android
作業系統的耗電量,賦值給osSipper
(494行定義)就可以了,這樣一個app
的計算就完成了,遍歷部分就不說了,儲存這個osSipper
是為了最後一步計算:
if (osSipper != null) {
// The device has probably been awake for longer than the screen on
// time and application wake lock time would account for. Assign
// this remainder to the OS, if possible.
mWakelockPowerCalculator.calculateRemaining(osSipper, mStats, mRawRealtime,
mRawUptime, mStatsType);
osSipper.sumPower();
}
主流程我們已經介紹完了,下面來看各個子模組耗電量的計算
Cpu耗電量
<device name="Android">
<!-- Most values are the incremental current used by a feature,
in mA (measured at nominal voltage).
The default values are deliberately incorrect dummy values.
OEM's must measure and provide actual values before
shipping a device.
Example real-world values are given in comments, but they
are totally dependent on the platform and can vary
significantly, so should be measured on the shipping platform
with a power meter. -->
<item name="none">0</item>
<item name="screen.on">0.1</item> <!-- ~200mA -->
<item name="screen.full">0.1</item> <!-- ~300mA -->
<item name="bluetooth.active">0.1</item> <!-- Bluetooth data transfer, ~10mA -->
<item name="bluetooth.on">0.1</item> <!-- Bluetooth on & connectable, but not connected, ~0.1mA -->
<item name="wifi.on">0.1</item> <!-- ~3mA -->
<item name="wifi.active">0.1</item> <!-- WIFI data transfer, ~200mA -->
<item name="wifi.scan">0.1</item> <!-- WIFI network scanning, ~100mA -->
<item name="dsp.audio">0.1</item> <!-- ~10mA -->
<item name="dsp.video">0.1</item> <!-- ~50mA -->
<item name="camera.flashlight">0.1</item> <!-- Avg. power for camera flash, ~160mA -->
<item name="camera.avg">0.1</item> <!-- Avg. power use of camera in standard usecases, ~550mA -->
<item name="radio.active">0.1</item> <!-- ~200mA -->
<item name="radio.scanning">0.1</item> <!-- cellular radio scanning for signal, ~10mA -->
<item name="gps.on">0.1</item> <!-- ~50mA -->
<!-- Current consumed by the radio at different signal strengths, when paging -->
<array name="radio.on"> <!-- Strength 0 to BINS-1 -->
<value>0.2</value> <!-- ~2mA -->
<value>0.1</value> <!-- ~1mA -->
</array>
<!-- Different CPU speeds as reported in
/sys/devices/system/cpu/cpu0/cpufreq/stats/time_in_state -->
<array name="cpu.speeds">
<value>400000</value> <!-- 400 MHz CPU speed -->
</array>
<!-- Current when CPU is idle -->
<item name="cpu.idle">0.1</item>
<!-- Current at each CPU speed, as per 'cpu.speeds' -->
<array name="cpu.active">
<value>0.1</value> <!-- ~100mA -->
</array>
<!-- This is the battery capacity in mAh (measured at nominal voltage) -->
<item name="battery.capacity">1000</item>
<array name="wifi.batchedscan"> <!-- mA -->
<value>.0002</value> <!-- 1-8/hr -->
<value>.002</value> <!-- 9-64/hr -->
<value>.02</value> <!-- 65-512/hr -->
<value>.2</value> <!-- 513-4,096/hr -->
<value>2</value> <!-- 4097-/hr -->
</array>
</device>
這個裡面儲存了Cpu(cpu.speeds)的主頻等級,以及每個主頻每秒消耗的毫安(cpu.active),好,現在回到CpuPowerCalculator
中,先來看構造方法
public CpuPowerCalculator(PowerProfile profile) {
final int speedSteps = profile.getNumSpeedSteps();
mPowerCpuNormal = new double[speedSteps];
mSpeedStepTimes = new long[speedSteps];
for (int p = 0; p < speedSteps; p++) {
mPowerCpuNormal[p] = profile.getAveragePower(PowerProfile.POWER_CPU_ACTIVE, p);
}
}
第一步獲得Cpu
有幾個主頻等級,因為不同等級消耗的電量不一樣,所以要區別對待,根據主頻的個數,然後初始化mPowerCpuNormal
和mSpeedStepTimes
,前者用來儲存不同等級的耗電速度,後者用來儲存在不同等級上耗時,然後給mPowerCpuNormal
的每個元素附上值。構造方法就完成了其所有的工作,現在來計算方法calculateApp
,
final int speedSteps = mSpeedStepTimes.length;
long totalTimeAtSpeeds = 0;
for (int step = 0; step < speedSteps; step++) {
mSpeedStepTimes[step] = u.getTimeAtCpuSpeed(step, statsType);
totalTimeAtSpeeds += mSpeedStepTimes[step];
}
totalTimeAtSpeeds = Math.max(totalTimeAtSpeeds, 1);
首先得到Cpu
主頻等級個數,然後BatteryStats.Uid
得到不同主頻上執行時間,計算Cpu
總耗時儲存在totalTimeAtSpeeds
中,
app.cpuTimeMs = (u.getUserCpuTimeUs(statsType) + u.getSystemCpuTimeUs(statsType)) / 1000;
Cpu
的執行時間分很多部分,但是我們關注User
和Kernal
部分,也就是上面的UserCpuTime
和SystemCpuTime
。
double cpuPowerMaMs = 0;
for (int step = 0; step < speedSteps; step++) {
final double ratio = (double) mSpeedStepTimes[step] / totalTimeAtSpeeds;
final double cpuSpeedStepPower = ratio * app.cpuTimeMs * mPowerCpuNormal[step];
if (DEBUG && ratio != 0) {
Log.d(TAG, "UID " + u.getUid() + ": CPU step #"
+ step + " ratio=" + BatteryStatsHelper.makemAh(ratio) + " power="
+ BatteryStatsHelper.makemAh(cpuSpeedStepPower / (60 * 60 * 1000)));
}
cpuPowerMaMs += cpuSpeedStepPower;
}
上面的程式碼就是將不同主頻的消耗累加到一起,但是其中值得注意的是,他並不是用各個主頻的消耗時間*主頻單位時間內消耗的電量,而是用一個radio變數來計算得到各個主頻段執行時間佔總時間的百分比,然後用cpuTimeMs
來換算成各個主頻的Cpu實際消耗時間,這比5.0的API多了這麼一步,我估計是發現了計算的不嚴謹性,這也是Android
遲遲不放出統計電量方式的原因,其實google自己對這塊也沒有把握,所以才會造成不同API
計算方式的差異。好,計算完我們的總消耗後,是不是就算完事了?如果你只需要得到一個App的耗電總量,上面的講解已經足夠了,但是6.0的API計算了每個App的不同程序的耗電量,這個我們就只當看看就行,暫時沒什麼實際意義。
// Keep track of the package with highest drain.
double highestDrain = 0;
app.cpuFgTimeMs = 0;
final ArrayMap<String, ? extends BatteryStats.Uid.Proc> processStats = u.getProcessStats();
final int processStatsCount = processStats.size();
for (int i = 0; i < processStatsCount; i++) {
final BatteryStats.Uid.Proc ps = processStats.valueAt(i);
final String processName = processStats.keyAt(i);
app.cpuFgTimeMs += ps.getForegroundTime(statsType);
final long costValue = ps.getUserTime(statsType) + ps.getSystemTime(statsType)
+ ps.getForegroundTime(statsType);
// Each App can have multiple packages and with multiple running processes.
// Keep track of the package who's process has the highest drain.
if (app.packageWithHighestDrain == null ||
app.packageWithHighestDrain.startsWith("*")) {
highestDrain = costValue;
app.packageWithHighestDrain = processName;
} else if (highestDrain < costValue && !processName.startsWith("*")) {
highestDrain = costValue;
app.packageWithHighestDrain = processName;
}
}
// Ensure that the CPU times make sense.
if (app.cpuFgTimeMs > app.cpuTimeMs) {
if (DEBUG && app.cpuFgTimeMs > app.cpuTimeMs + 10000) {
Log.d(TAG, "WARNING! Cputime is more than 10 seconds behind Foreground time");
}
// Statistics may not have been gathered yet.
app.cpuTimeMs = app.cpuFgTimeMs;
}
上面統計同一App
下不同的程序的耗電量,得到消耗最大的程序名,儲存到BatterySipper
物件中,然後得出App
的Cpu
的foreground
消耗時間,將foreground
時間與之前計算得到的cpuTimeMs
進行比較,如果foreground
時間比cpuTimeMs
還要大,那麼就將cpuTimeMs
的時間改變為foreground
的值,但是這個值的變化對之前耗電總量的計算沒有絲毫影響。
// Convert the CPU power to mAh
app.cpuPowerMah = cpuPowerMaMs / (60 * 60 * 1000);
最後的最後,將耗電量用mAh單位來表示,所以在毫秒的基礎上除以60*60*1000
。
總結:Cpu
耗電量的計算是要區分不同主頻的,頻率不同,單位時間內消耗的電量是有區分的,這一點要明白。還有一點就是不同主頻上的執行時間不是通過BatteryStats.Uid#getTimeAtCpuSpeed
方法得到的,二十是通過百分比和BatteryStats.Uid#getUserCpuTimeUs
和getSystemCpuTimeUs
計算得到cpuTimeMs
乘積得到的。最後一點就是,cpuTimeMs
時間是會在計算完畢後進行比較,比較的物件是CPU
的foreground
時間。
WakeLock耗電量的計算
從構造方法開始,
public WakelockPowerCalculator(PowerProfile profile) {
mPowerWakelock = profile.getAveragePower(PowerProfile.POWER_CPU_AWAKE);
}
首先得到power_profile.xml
中cpu.awake
表示的值,儲存在mPowerWakelock
變數中。構造方法只做了這麼點事,下面進入calculateApp
方法。
@Override
public void calculateApp(BatterySipper app, BatteryStats.Uid u, long rawRealtimeUs,
long rawUptimeUs, int statsType) {
long wakeLockTimeUs = 0;
final ArrayMap<String, ? extends BatteryStats.Uid.Wakelock> wakelockStats =
u.getWakelockStats();
final int wakelockStatsCount = wakelockStats.size();
for (int i = 0; i < wakelockStatsCount; i++) {
final BatteryStats.Uid.Wakelock wakelock = wakelockStats.valueAt(i);
// Only care about partial wake locks since full wake locks
// are canceled when the user turns the screen off.
BatteryStats.Timer timer = wakelock.getWakeTime(BatteryStats.WAKE_TYPE_PARTIAL);
if (timer != null) {
wakeLockTimeUs += timer.getTotalTimeLocked(rawRealtimeUs, statsType);
}
}
app.wakeLockTimeMs = wakeLockTimeUs / 1000; // convert to millis
mTotalAppWakelockTimeMs += app.wakeLockTimeMs;
// Add cost of holding a wake lock.
app.wakeLockPowerMah = (app.wakeLockTimeMs * mPowerWakelock) / (1000*60*60);
if (DEBUG && app.wakeLockPowerMah != 0) {
Log.d(TAG, "UID " + u.getUid() + ": wake " + app.wakeLockTimeMs
+ " power=" + BatteryStatsHelper.makemAh(app.wakeLockPowerMah));
}
}
首先獲得Wakelock
的數量,然後逐個遍歷得到每個Wakelock
物件,得到該物件後,得到BatteryStats.WAKE_TYPE_PARTIAL
的喚醒時間,然後累加,其實wakelock
有4種,為什麼只取partial
的時間,具體程式碼google
也沒解釋的很清楚,只是用一句註釋打發了我們。得到總時間後,就可以與構造方法中的單位時間waklock
消耗電量相乘得到Wakelock
消耗的總電量。
Wifi耗電量的計算
首先來看構造方法,來了解一下WIFI的耗電量計算用到了power_profile.xml
中的哪些屬性:
public WifiPowerCalculator(PowerProfile profile) {
mIdleCurrentMa = profile.getAveragePower(PowerProfile.POWER_WIFI_CONTROLLER_IDLE);
mTxCurrentMa = profile.getAveragePower(PowerProfile.POWER_WIFI_CONTROLLER_TX);
mRxCurrentMa = profile.getAveragePower(PowerProfile.POWER_WIFI_CONTROLLER_RX);
}
public static final String POWER_WIFI_CONTROLLER_IDLE = "wifi.controller.idle";
public static final String POWER_WIFI_CONTROLLER_RX = "wifi.controller.rx";
public static final String POWER_WIFI_CONTROLLER_TX = "wifi.controller.tx";
知道對應的xml的屬性後我們直接看calculateApp
方法:
@Override
public void calculateApp(BatterySipper app, BatteryStats.Uid u, long rawRealtimeUs,
long rawUptimeUs, int statsType) {
final long idleTime = u.getWifiControllerActivity(BatteryStats.CONTROLLER_IDLE_TIME,
statsType);
final long txTime = u.getWifiControllerActivity(BatteryStats.CONTROLLER_TX_TIME, statsType);
final long rxTime = u.getWifiControllerActivity(BatteryStats.CONTROLLER_RX_TIME, statsType);
app.wifiRunningTimeMs = idleTime + rxTime + txTime;
app.wifiPowerMah =
((idleTime * mIdleCurrentMa) + (txTime * mTxCurrentMa) + (rxTime * mRxCurrentMa))
/ (1000*60*60);
mTotalAppPowerDrain += app.wifiPowerMah;
app.wifiRxPackets = u.getNetworkActivityPackets(BatteryStats.NETWORK_WIFI_RX_DATA,
statsType);
app.wifiTxPackets = u.getNetworkActivityPackets(BatteryStats.NETWORK_WIFI_TX_DATA,
statsType);
app.wifiRxBytes = u.getNetworkActivityBytes(BatteryStats.NETWORK_WIFI_RX_DATA,
statsType);
app.wifiTxBytes = u.getNetworkActivityBytes(BatteryStats.NETWORK_WIFI_TX_DATA,
statsType);
if (DEBUG && app.wifiPowerMah != 0) {
Log.d(TAG, "UID " + u.getUid() + ": idle=" + idleTime + "ms rx=" + rxTime + "ms tx=" +
txTime + "ms power=" + BatteryStatsHelper.makemAh(app.wifiPowerMah));
}
}
這裡的計算方式也是差不多,先根據Uid得到時間,然後乘以構造方法裡對應的wifi型別單位時間內消耗電量值,沒什麼難點,就不一一分析,需要注意的是,這裡面還計算了wifi
傳輸的資料包的數量和位元組數。
藍芽耗電量的計算
藍芽關注的power_profile.xml
中的屬性如下:
public static final String POWER_BLUETOOTH_CONTROLLER_IDLE = "bluetooth.controller.idle";
public static final String POWER_BLUETOOTH_CONTROLLER_RX = "bluetooth.controller.rx";
public static final String POWER_BLUETOOTH_CONTROLLER_TX = "bluetooth.controller.tx";
但是還沒有單獨為App計算耗電量的,所以這個地方是空的。
@Override
public void calculateApp(BatterySipper app, BatteryStats.Uid u, long rawRealtimeUs,
long rawUptimeUs, int statsType) {
// No per-app distribution yet.
}
攝像頭耗電量的計算
攝像頭的耗電量關注的是power_profile.xml
中camera.avg
屬性代表的值,儲存到mCameraPowerOnAvg
,
public static final String POWER_CAMERA = "camera.avg";
計算方式如下:
@Override
public void calculateApp(BatterySipper app, BatteryStats.Uid u, long rawRealtimeUs,
long rawUptimeUs, int statsType) {
// Calculate camera power usage. Right now, this is a (very) rough estimate based on the
// average power usage for a typical camera application.
final BatteryStats.Timer timer = u.getCameraTurnedOnTimer();
if (timer != null) {
final long totalTime = timer.getTotalTimeLocked(rawRealtimeUs, statsType) / 1000;
app.cameraTimeMs = totalTime;
app.cameraPowerMah = (totalTime * mCameraPowerOnAvg) / (1000*60*60);
} else {
app.cameraTimeMs = 0;
app.cameraPowerMah = 0;
}
}
先計算攝像頭開啟的時間totalTime
,然後根據這個值乘以mCameraPowerOnAvg
得到攝像頭的耗電量。
手電筒耗電量的計算
public static final String POWER_FLASHLIGHT = "camera.flashlight";
跟攝像頭類似,也是先得到時間,然後乘積,不想說了,沒意思。
無線電耗電量的計算
關注的是power_profile.xml
中如下三個屬性:
/**
* Power consumption when screen is on, not including the backlight power.
*/
public static final String POWER_SCREEN_ON = "screen.on";
/**
* Power consumption when cell radio is on but not on a call.
*/
public static final String POWER_RADIO_ON = "radio.on";
/**
* Power consumption when cell radio is hunting for a signal.
*/
public static final String POWER_RADIO_SCANNING = "radio.scanning";
當無限量連線上時,根據訊號強度不同,耗電量的計算是有區別的,所以在構造方法,當無線電的狀態為on時,是要特殊處理的,其他兩個狀態(active和scan)就正常取值就可以了。
/**
* Power consumption when screen is on, not including the backlight power.
*/
public static final String POWER_SCREEN_ON = "screen.on";
/**
* Power consumption when cell radio is on but not on a call.
*/
public static final String POWER_RADIO_ON = "radio.on";
/**
* Power consumption when cell radio is hunting for a signal.
*/
public static final String POWER_RADIO_SCANNING = "radio.scanning";
計算的方式分兩種,以無線電處於active
狀態的次數為區分,當active
大於0,我們用處於active
狀態的時間來乘以它的單位耗時。另一種情況就要根據網路轉化的資料包來計算耗電量了。
感測器耗電量的計算
只關注一個屬性:
public static final String POWER_GPS_ON = "gps.on";
計算方式如下:
@Override
public void calculateApp(BatterySipper app, BatteryStats.Uid u, long rawRealtimeUs,
long rawUptimeUs, int statsType) {
// Process Sensor usage
final SparseArray<? extends BatteryStats.Uid.Sensor> sensorStats = u.getSensorStats();
final int NSE = sensorStats.size();
for (int ise = 0; ise < NSE; ise++) {
final BatteryStats.Uid.Sensor sensor = sensorStats.valueAt(ise);
final int sensorHandle = sensorStats.keyAt(ise);
final BatteryStats.Timer timer = sensor.getSensorTime();
final long sensorTime = timer.getTotalTimeLocked(rawRealtimeUs, statsType) / 1000;
switch (sensorHandle) {
case BatteryStats.Uid.Sensor.GPS:
app.gpsTimeMs = sensorTime;
app.gpsPowerMah = (app.gpsTimeMs * mGpsPowerOn) / (1000*60*60);
break;
default:
final int sensorsCount = mSensors.size();
for (int i = 0; i < sensorsCount; i++) {
final Sensor s = mSensors.get(i);
if (s.getHandle() == sensorHandle) {
app.sensorPowerMah += (sensorTime * s.getPower()) / (1000*60*60);
break;
}
}
break;
}
}
}
當感測器的型別為GPS時,我們計算每個感測器的時間然後乘以耗電量,和所有的耗電量計算都是一樣,不同的是,當感測器不是GPS時,這個時候計算就根據SensorManager
得到所有感測器型別,這個裡面儲存有不同感測器的單位耗電量,這樣就能計算不同感測器的耗電量。
總結
至此我已經把App耗電量的計算講完了(還有硬體),前後花費3天時間,好痛苦(此處一萬隻草泥馬),不過好在自己也算對這個耗電量的理解有了一定的認識。google官方對耗電量的統計給出的解釋都是不能代表真實資料,只能作為參考值,因為受power_profile.xml的干擾太大,如果手機廠商沒有嚴格設定這個檔案,那可想而知出來的值可能是不合理的。
提示
騰訊的GT團隊前幾天推出了耗電量的計算APK,原理是一樣的,大家可以試用下GT