BatteryStatsHelper.java源码分析

在分析PowerUsageSummary的时候，其实可以发现主要获取应用和服务电量使用情况的实现是在BatteryStatsHelper.java中

还是在线网站http://androidxref.com/上对Android版本6.0.1_r10源码进行分析

具体位置在 /frameworks/base/core/java/com/android/internal/os/BatteryStatsHelper.java

create方法

查看构造方法

public BatteryStatsHelper(Context context) {
    this(context, true);
}

public BatteryStatsHelper(Context context, boolean collectBatteryBroadcast) {
    this(context, collectBatteryBroadcast, checkWifiOnly(context));
}

public BatteryStatsHelper(Context context, boolean collectBatteryBroadcast, boolean wifiOnly) {
    mContext = context;
    mCollectBatteryBroadcast = collectBatteryBroadcast;
    mWifiOnly = wifiOnly;
}

设置是否需要注册BATTERY_CHANGED驻留广播，该广播监听系统电池电量和充电状态

mCollectBatteryBroadcast = collectBatteryBroadcast;

设备是否只有wifi，无移动网络，比如说平板或者车机，有的就是不能插SIM卡的

mWifiOnly = wifiOnly;

查看create方法

public void create(BatteryStats stats) {
    mPowerProfile = new PowerProfile(mContext);
    mStats = stats;
}

public void create(Bundle icicle) {
    if (icicle != null) {
        mStats = sStatsXfer;
        mBatteryBroadcast = sBatteryBroadcastXfer;
    }
    mBatteryInfo = IBatteryStats.Stub.asInterface(
        ServiceManager.getService(BatteryStats.SERVICE_NAME));
    mPowerProfile = new PowerProfile(mContext);
}

其中都获取了PowerProfile对象

mPowerProfile = new PowerProfile(mContext);

PowerProfile创建

持续跟进

public PowerProfile(Context context) {
    // Read the XML file for the given profile (normally only one per
    // device)
    if (sPowerMap.size() == 0) {
        readPowerValuesFromXml(context);
    }
    initCpuClusters();
}

可以看到这里有一段注释： Read the XML file for the given profile (normally only one perdevice

跟进readPowerValuesFromXml方法，其实这个方法就是用来解析power_profile.xml文件的，该文件在源码中的位置为 /frameworks/base/core/res/res/xml/power_profile.xml，power_profile.xml是一个可配置的功耗数据文件

private void readPowerValuesFromXml(Context context) {
    int id = com.android.internal.R.xml.power_profile;
    final Resources resources = context.getResources();
    XmlResourceParser parser = resources.getXml(id);
    boolean parsingArray = false;
    ArrayList<Double> array = new ArrayList<Double>();
    String arrayName = null;

    try {
        // ....

在这里需要提一下Android中对于应用和硬件的耗电量计算方式：

有一张“价格表”，记录每种硬件1秒钟耗多少电。有一张“购物清单”，记录apk使用了哪几种硬件，每种硬件用了多长时间。假设某个应用累计使用了60秒的cpu，cpu1秒钟耗1mAh，那这个应用就消耗了60mAh的电

这里的价格表就是我们找到的power_profile.xml文件，手机的硬件是各不相同的，所以每一款手机都会有一张自己的"价格表"，这张表的准确性由手机厂商负责。

这也是为什么我们碰到读取xml文件的时候注释里面会有normally only one perdevice

如果我们想要看自己手机的power_profile.xml文件咋办，它会存储在手机的/system/framework/framework-res.apk路径中，我们可以将它pull出来，通过反编译的手法获得power_profile.xml文件

refreshStats方法

接着可以看到重载的refreshStats

/**
 * Refreshes the power usage list.
 */
public void refreshStats(int statsType, int asUser) {
    SparseArray<UserHandle> users = new SparseArray<>(1);
    users.put(asUser, new UserHandle(asUser));
    refreshStats(statsType, users);
}

/**
 * Refreshes the power usage list.
 */
public void refreshStats(int statsType, List<UserHandle> asUsers) {
    final int n = asUsers.size();
    SparseArray<UserHandle> users = new SparseArray<>(n);
    for (int i = 0; i < n; ++i) {
        UserHandle userHandle = asUsers.get(i);
        users.put(userHandle.getIdentifier(), userHandle);
    }
    refreshStats(statsType, users);
}

/**
 * Refreshes the power usage list.
 */
public void refreshStats(int statsType, SparseArray<UserHandle> asUsers) {
    refreshStats(statsType, asUsers, SystemClock.elapsedRealtime() * 1000,
                 SystemClock.uptimeMillis() * 1000);
}

refreshStats是刷新电池使用数据的接口，向上提供数据，其中的具体实现在

public void refreshStats(int statsType, SparseArray<UserHandle> asUsers, long rawRealtimeUs,
            long rawUptimeUs) {
    // Initialize mStats if necessary.
    getStats();

    mMaxPower = 0;
    mMaxRealPower = 0;
    mComputedPower = 0;
    mTotalPower = 0;

    mUsageList.clear();
    mWifiSippers.clear();
    mBluetoothSippers.clear();
    mUserSippers.clear();
    mMobilemsppList.clear();

    if (mStats == null) {
        return;
    }

    if (mCpuPowerCalculator == null) {
        mCpuPowerCalculator = new CpuPowerCalculator(mPowerProfile);
    }
    mCpuPowerCalculator.reset();

    if (mWakelockPowerCalculator == null) {
        mWakelockPowerCalculator = new WakelockPowerCalculator(mPowerProfile);
    }
    mWakelockPowerCalculator.reset();

    if (mMobileRadioPowerCalculator == null) {
        mMobileRadioPowerCalculator = new MobileRadioPowerCalculator(mPowerProfile, mStats);
    }
    mMobileRadioPowerCalculator.reset(mStats);

    // checkHasWifiPowerReporting can change if we get energy data at a later point, so
    // always check this field.
    final boolean hasWifiPowerReporting = checkHasWifiPowerReporting(mStats, mPowerProfile);
    if (mWifiPowerCalculator == null || hasWifiPowerReporting != mHasWifiPowerReporting) {
        mWifiPowerCalculator = hasWifiPowerReporting ?
            new WifiPowerCalculator(mPowerProfile) :
        new WifiPowerEstimator(mPowerProfile);
        mHasWifiPowerReporting = hasWifiPowerReporting;
    }
    mWifiPowerCalculator.reset();

    final boolean hasBluetoothPowerReporting = checkHasBluetoothPowerReporting(mStats,
                                                                               mPowerProfile);
    if (mBluetoothPowerCalculator == null ||
        hasBluetoothPowerReporting != mHasBluetoothPowerReporting) {
        mBluetoothPowerCalculator = new BluetoothPowerCalculator(mPowerProfile);
        mHasBluetoothPowerReporting = hasBluetoothPowerReporting;
    }
    mBluetoothPowerCalculator.reset();

    if (mSensorPowerCalculator == null) {
        mSensorPowerCalculator = new SensorPowerCalculator(mPowerProfile,
                                                           (SensorManager) mContext.getSystemService(Context.SENSOR_SERVICE));
    }
    mSensorPowerCalculator.reset();

    if (mCameraPowerCalculator == null) {
        mCameraPowerCalculator = new CameraPowerCalculator(mPowerProfile);
    }
    mCameraPowerCalculator.reset();

    if (mFlashlightPowerCalculator == null) {
        mFlashlightPowerCalculator = new FlashlightPowerCalculator(mPowerProfile);
    }
    mFlashlightPowerCalculator.reset();

    mStatsType = statsType;
    mRawUptime = rawUptimeUs;
    mRawRealtime = rawRealtimeUs;
    mBatteryUptime = mStats.getBatteryUptime(rawUptimeUs);
    mBatteryRealtime = mStats.getBatteryRealtime(rawRealtimeUs);
    mTypeBatteryUptime = mStats.computeBatteryUptime(rawUptimeUs, mStatsType);
    mTypeBatteryRealtime = mStats.computeBatteryRealtime(rawRealtimeUs, mStatsType);
    mBatteryTimeRemaining = mStats.computeBatteryTimeRemaining(rawRealtimeUs);
    mChargeTimeRemaining = mStats.computeChargeTimeRemaining(rawRealtimeUs);

    if (DEBUG) {
        Log.d(TAG, "Raw time: realtime=" + (rawRealtimeUs/1000) + " uptime="
              + (rawUptimeUs/1000));
        Log.d(TAG, "Battery time: realtime=" + (mBatteryRealtime/1000) + " uptime="
              + (mBatteryUptime/1000));
        Log.d(TAG, "Battery type time: realtime=" + (mTypeBatteryRealtime/1000) + " uptime="
              + (mTypeBatteryUptime/1000));
    }
    mMinDrainedPower = (mStats.getLowDischargeAmountSinceCharge()
                        * mPowerProfile.getBatteryCapacity()) / 100;
    mMaxDrainedPower = (mStats.getHighDischargeAmountSinceCharge()
                        * mPowerProfile.getBatteryCapacity()) / 100;

    processAppUsage(asUsers);

    // Before aggregating apps in to users, collect all apps to sort by their ms per packet.
    for (int i=0; i<mUsageList.size(); i++) {
        BatterySipper bs = mUsageList.get(i);
        bs.computeMobilemspp();
        if (bs.mobilemspp != 0) {
            mMobilemsppList.add(bs);
        }
    }

    for (int i=0; i<mUserSippers.size(); i++) {
        List<BatterySipper> user = mUserSippers.valueAt(i);
        for (int j=0; j<user.size(); j++) {
            BatterySipper bs = user.get(j);
            bs.computeMobilemspp();
            if (bs.mobilemspp != 0) {
                mMobilemsppList.add(bs);
            }
        }
    }
    Collections.sort(mMobilemsppList, new Comparator<BatterySipper>() {
        @Override
        public int compare(BatterySipper lhs, BatterySipper rhs) {
            return Double.compare(rhs.mobilemspp, lhs.mobilemspp);
        }
    });

    processMiscUsage();

    Collections.sort(mUsageList);

    // At this point, we've sorted the list so we are guaranteed the max values are at the top.
    // We have only added real powers so far.
    if (!mUsageList.isEmpty()) {
        mMaxRealPower = mMaxPower = mUsageList.get(0).totalPowerMah;
        final int usageListCount = mUsageList.size();
        for (int i = 0; i < usageListCount; i++) {
            mComputedPower += mUsageList.get(i).totalPowerMah;
        }
    }

    if (DEBUG) {
        Log.d(TAG, "Accuracy: total computed=" + makemAh(mComputedPower) + ", min discharge="
              + makemAh(mMinDrainedPower) + ", max discharge=" + makemAh(mMaxDrainedPower));
    }

    mTotalPower = mComputedPower;
    if (mStats.getLowDischargeAmountSinceCharge() > 1) {
        if (mMinDrainedPower > mComputedPower) {
            double amount = mMinDrainedPower - mComputedPower;
            mTotalPower = mMinDrainedPower;
            BatterySipper bs = new BatterySipper(DrainType.UNACCOUNTED, null, amount);

            // Insert the BatterySipper in its sorted position.
            int index = Collections.binarySearch(mUsageList, bs);
            if (index < 0) {
                index = -(index + 1);
            }
            mUsageList.add(index, bs);
            mMaxPower = Math.max(mMaxPower, amount);
        } else if (mMaxDrainedPower < mComputedPower) {
            double amount = mComputedPower - mMaxDrainedPower;

            // Insert the BatterySipper in its sorted position.
            BatterySipper bs = new BatterySipper(DrainType.OVERCOUNTED, null, amount);
            int index = Collections.binarySearch(mUsageList, bs);
            if (index < 0) {
                index = -(index + 1);
            }
            mUsageList.add(index, bs);
            mMaxPower = Math.max(mMaxPower, amount);
        }
    }
}

我们依次分析

  • SparseArray<UserHandle> asUsers UserHanler代表设备上的一个用户
  • long rawRealtimeUs 系统开机后的运行时间
  • long rawUptimeUs 系统不包括休眠的运行时间
public void refreshStats(int statsType, SparseArray<UserHandle> asUsers, long rawRealtimeUs,
            long rawUptimeUs) {

初始化Stats操作

getStats()

如果mStats为空，则初始化

public BatteryStats getStats() {
    if (mStats == null) {
        load();
    }
    return mStats;
}
mMaxPower = 0; // 最大耗电量
mMaxRealPower = 0; // 最大真实耗电量
mComputedPower = 0; // 通过耗电计算器计算的耗电量总和
mTotalPower = 0; // 总的耗电量

刷新耗电量之前需要先清空之前的数据，clear都是清空操作

mUsageList.clear(); // 存储了BatterySipper列表，各类耗电量都存储在BatterySipper中，BatterySipper存储在mUsageList中
mWifiSippers.clear(); // 在统计软件耗电过程中使用到WIFI的应用，其对应的BatterySipper列表
mBluetoothSippers.clear(); // 在统计软件耗电过程中使用到BlueTooth的应用，其对应的BatterySipper列表
mUserSippers.clear(); // 设备上有多个用户时，存储了其他用户的耗电信息的SparseArray数据，键为userId，值为对应的List<BatterySipper>
mMobilemsppList.clear(); // 存储有数据接收和发送的BatterySipper对象的列表

初始化八大模块的耗电计算器，都继承于PowerCalculator抽象类，八大模块在processAppUsage方法中进行分析，这里只需要知道有哪八个以及进行的操作是初始化即可

计算项 Class文件
CPU功耗 mCpuPowerCalculator.java
Wakelock功耗 mWakelockPowerCalculator.java
无线电功耗 mMobileRadioPowerCalculator.java
WIFI功耗 mWifiPowerCalculator.java
蓝牙功耗 mBluetoothPowerCalculator.java
Sensor功耗 mSensorPowerCalculator.java
相机功耗 mCameraPowerCalculator.java
闪光灯功耗 mFlashlightPowerCalculator.java 
if (mCpuPowerCalculator == null) {
    mCpuPowerCalculator = new CpuPowerCalculator(mPowerProfile);
}
mCpuPowerCalculator.reset();

if (mWakelockPowerCalculator == null) {
    mWakelockPowerCalculator = new WakelockPowerCalculator(mPowerProfile);
}
mWakelockPowerCalculator.reset();

if (mMobileRadioPowerCalculator == null) {
    mMobileRadioPowerCalculator = new MobileRadioPowerCalculator(mPowerProfile, mStats);
}
mMobileRadioPowerCalculator.reset(mStats);

// checkHasWifiPowerReporting can change if we get energy data at a later point, so
// always check this field.
final boolean hasWifiPowerReporting = checkHasWifiPowerReporting(mStats, mPowerProfile);
if (mWifiPowerCalculator == null || hasWifiPowerReporting != mHasWifiPowerReporting) {
    mWifiPowerCalculator = hasWifiPowerReporting ?
        new WifiPowerCalculator(mPowerProfile) :
    new WifiPowerEstimator(mPowerProfile);
    mHasWifiPowerReporting = hasWifiPowerReporting;
}
mWifiPowerCalculator.reset();

final boolean hasBluetoothPowerReporting = checkHasBluetoothPowerReporting(mStats,
                                                                           mPowerProfile);
if (mBluetoothPowerCalculator == null ||
    hasBluetoothPowerReporting != mHasBluetoothPowerReporting) {
    mBluetoothPowerCalculator = new BluetoothPowerCalculator(mPowerProfile);
    mHasBluetoothPowerReporting = hasBluetoothPowerReporting;
}
mBluetoothPowerCalculator.reset();

if (mSensorPowerCalculator == null) {
    mSensorPowerCalculator = new SensorPowerCalculator(mPowerProfile,
                                                       (SensorManager) mContext.getSystemService(Context.SENSOR_SERVICE));
}
mSensorPowerCalculator.reset();

if (mCameraPowerCalculator == null) {
    mCameraPowerCalculator = new CameraPowerCalculator(mPowerProfile);
}
mCameraPowerCalculator.reset();

if (mFlashlightPowerCalculator == null) {
    mFlashlightPowerCalculator = new FlashlightPowerCalculator(mPowerProfile);
}
mFlashlightPowerCalculator.reset();

电量统计需要先设置统计时间段，通过设置统计类型mStatsType变量来表示

mStatsType = statsType;

有三种可选值

  // 统计从上一次充电以来至现在的耗电量
  public static final int STATS_SINCE_CHARGED = 0;

  // 统计系统启动以来到现在的耗电量
  public static final int STATS_CURRENT = 1;

  // 统计从上一次拔掉USB线以来到现在的耗电量
  public static final int STATS_SINCE_UNPLUGGED = 2;

当前系统的运行时间

mRawUptimeUs = rawUptimeUs;

当前系统的真实运行时间，包括休眠时间

mRawRealtimeUs = rawRealtimeUs;

剩下的也是一堆时间

mBatteryUptime = mStats.getBatteryUptime(rawUptimeUs); // 电池放电运行时间
mBatteryRealtime = mStats.getBatteryRealtime(rawRealtimeUs); // 电池真实放电运行时间，包含休眠时间
mTypeBatteryUptime = mStats.computeBatteryUptime(rawUptimeUs, mStatsType); // 对应类型的电池放电运行时间，如上次充满电后的电池运行时间
mTypeBatteryRealtime = mStats.computeBatteryRealtime(rawRealtimeUs, mStatsType); // 对应类型的电池放电运行时间,包括休眠时间
mBatteryTimeRemaining = mStats.computeBatteryTimeRemaining(rawRealtimeUs); // 电池预计使用时长
mChargeTimeRemaining = mStats.computeChargeTimeRemaining(rawRealtimeUs); // 电池预计多久充满时长

DEBUG模式下会输出时间日志，这不重要

if (DEBUG) {
    Log.d(TAG, "Raw time: realtime=" + (rawRealtimeUs/1000) + " uptime="
          + (rawUptimeUs/1000));
    Log.d(TAG, "Battery time: realtime=" + (mBatteryRealtime/1000) + " uptime="
          + (mBatteryUptime/1000));
    Log.d(TAG, "Battery type time: realtime=" + (mTypeBatteryRealtime/1000) + " uptime="
          + (mTypeBatteryUptime/1000));
}

计算最低和最高的电量近似值

该方法待会详细说明，现在我们只需要知道它主要进行统计APP软件的耗电量操作，统计之后会将每种类型，每个UID的耗电值存储在对应的BatterySipper中

processAppUsage(asUsers);

对每个应用程序的每毫秒ms接收和发送的数据包mobilemspp进行排序

for (int i=0; i<mUsageList.size(); i++) {
    BatterySipper bs = mUsageList.get(i);
    bs.computeMobilemspp();
    if (bs.mobilemspp != 0) {
        mMobilemsppList.add(bs);
    }
}
// 遍历其他用户的耗电情况
for (int i=0; i<mUserSippers.size(); i++) {
    List<BatterySipper> user = mUserSippers.valueAt(i);
    for (int j=0; j<user.size(); j++) {
        BatterySipper bs = user.get(j);
        bs.computeMobilemspp();
        if (bs.mobilemspp != 0) {
            mMobilemsppList.add(bs);
        }
    }
}

对mMobilemsppList进行排序

Collections.sort(mMobilemsppList, new Comparator<BatterySipper>() {
    @Override
    public int compare(BatterySipper lhs, BatterySipper rhs) {
        return Double.compare(rhs.mobilemspp, lhs.mobilemspp);
    }
});

计算硬件的耗电量，跟前面的processAppUsage(asUsers);对应，这两个方法我们都后面再说

processMiscUsage();

对软硬件耗电量结果进行降序排序

Collections.sort(mUsageList);

获取最大耗电量

因为我们刚才进行了排序，所以耗电最多的硬件/软件正位于顶部，赋值mMaxRealPower最大真实耗电量

遍历usageList计算得到mComputedPower耗电量总和

if (!mUsageList.isEmpty()) {
    mMaxRealPower = mMaxPower = mUsageList.get(0).totalPowerMah;
    final int usageListCount = mUsageList.size();
    for (int i = 0; i < usageListCount; i++) {
        mComputedPower += mUsageList.get(i).totalPowerMah;
    }
}

如果存在未计算到的耗电量，实例化一个DrainType.UNACCOUNTED类型的BatterySipper进行存储，并添加到mUsageList中

mTotalPower = mComputedPower;
if (mStats.getLowDischargeAmountSinceCharge() > 1) {
    // 如果最低放电量 > 计算的总耗电量，说明还有未计算的
    if (mMinDrainedPower > mComputedPower) {
        double amount = mMinDrainedPower - mComputedPower;
        mTotalPower = mMinDrainedPower;
        // 实例化一个DrainType.UNACCOUNTED类型的BatterySipper，用来存储未计算的耗电量
        BatterySipper bs = new BatterySipper(DrainType.UNACCOUNTED, null, amount);

        // Insert the BatterySipper in its sorted position.
        int index = Collections.binarySearch(mUsageList, bs);
        if (index < 0) {
            index = -(index + 1);
        }
        mUsageList.add(index, bs);
        mMaxPower = Math.max(mMaxPower, amount);
    }

如果存在计算多了的耗电量，实例化一个DrainType.OVERCOUNTED类型的BatterySipper进行存储，并添加到mUsageList中

// 如果最高放电量 < 计算的总耗电量，说明多算了耗电量
else if (mMaxDrainedPower < mComputedPower) {
        double amount = mComputedPower - mMaxDrainedPower;
    
        // Insert the BatterySipper in its sorted position.
        BatterySipper bs = new BatterySipper(DrainType.OVERCOUNTED, null, amount);
        int index = Collections.binarySearch(mUsageList, bs);
        if (index < 0) {
            index = -(index + 1);
        }
        mUsageList.add(index, bs);
        mMaxPower = Math.max(mMaxPower, amount);
    }
}

这篇已经太长了，关于软硬件的耗电量计算就在另外一篇里面写吧

参考链接

END

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本文作者：春告鳥
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