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1. 剩余可用时长 BatteryStatsImpl.computeBatteryTimeRemaining 函数
http://androidxref.com/9.0.0_r3/xref/frameworks/base/core/java/com/android/internal/os/BatteryStatsImpl.java
**公式:剩余电池可用时长 = 每消耗1%的电量的平均时间 * 当前电量值 **
原理:统计出每次放电的电量变化的时间,获得每消耗1%的电量的平均时间,再根据当前电量值,从而得到预计可以时长
@Overridepublic long computeBatteryTimeRemaining(long curTime) {// 当前为充电状态,则无剩余可用时长if (!mOnBattery) {return -1;}// 无放电电池信息,则无剩余可用时长if (mDischargeStepTracker.mNumStepDurations < 1) {return -1;}// 无每消耗1%的电量的平均时间,则无剩余可用时长long msPerLevel = mDischargeStepTracker.computeTimePerLevel();if (msPerLevel <= 0) {return -1;}// 剩余电池可用时长 = 每消耗1%的电量的平均时间 * 当前电量值 return (msPerLevel * mCurrentBatteryLevel) * 1000;}
1.1 是否充电状态 - mOnBattery
boolean mOnBattery;// This should probably be exposed in the API, though it's not criticalpublic static final int BATTERY_PLUGGED_NONE = OsProtoEnums.BATTERY_PLUGGED_NONE; // = 0// Plug states, primarily used by android/os/BatteryManager.java.enum BatteryPluggedStateEnum {// Note that NONE is not in BatteryManager.java's constants.BATTERY_PLUGGED_NONE = 0;// Power source is an AC charger.BATTERY_PLUGGED_AC = 1;// Power source is a USB port.BATTERY_PLUGGED_USB = 2;// Power source is wireless.BATTERY_PLUGGED_WIRELESS = 4;}public static boolean isOnBattery(int plugType, int status) {// 当前未充电 && 当前电池状态不为未知状态return plugType == BATTERY_PLUGGED_NONE && status != BatteryManager.BATTERY_STATUS_UNKNOWN;}@GuardedBy("this")public void setBatteryStateLocked(final int status, final int health, final int plugType,final int level, /* not final */ int temp, final int volt, final int chargeUAh,final int chargeFullUAh) {final boolean onBattery = isOnBattery(plugType, status);...setOnBatteryLocked(elapsedRealtime, uptime, onBattery, oldStatus, level, chargeUAh);...}@GuardedBy("this")protected void setOnBatteryLocked(final long mSecRealtime, final long mSecUptime,final boolean onBattery, final int oldStatus, final int level, final int chargeUAh) {...if (onBattery) {mOnBattery = mOnBatteryInternal = true;} else {mOnBattery = mOnBatteryInternal = false;}...}
1.2 放电电池信息条数 mDischargeStepTracker.mNumStepDurations
查看 batterystats-daily.xml 电池信息条数,例如记录不同时间的灭屏、亮屏、省电模式、idle模式、充放电等信息
// 读取每日电池信息public void readDailyStatsLocked() {...// 电池每日使用信息// 路径: /data/system/batterystats-daily.xml// 0x 00 00 00 ffffffffff// 0x 00[modMode] 00[initMode] level 时间(duration)// initMode和modMode 中:// 00(灭屏 f) 01(亮屏 o) 02(doze d) 03(doze supend z)// 04(省电模式 p) 08(idle模式 i)mDailyFile = new AtomicFile(new File(systemDir, "batterystats-daily.xml"));stream = mDailyFile.openRead();parser.setInput(stream, StandardCharsets.UTF_8.name());...readDailyItemsLocked(parser);...}void readDailyItemTagDetailsLocked(XmlPullParser parser, DailyItem dit, boolean isCharge,String tag)throws NumberFormatException, XmlPullParserException, IOException {...if ("s".equals(tagName)) {if (i < num) {String valueAttr = parser.getAttributeValue(null, "v");if (valueAttr != null) {// 例如 0x020362ffffffff00L:zD-62-ffffffff00// 表示当前为doze supend,上一次为 doze,电量为 0x62, 时间为ffffffff00steps.decodeEntryAt(i, valueAttr);i++;}}}...// 每日电池信息steps.mNumStepDurations = i;...}
1.3 每消耗1%的电量的平均时间 mDischargeStepTracker.computeTimePerLevel()
public static final long STEP_LEVEL_TIME_MASK = 0x000000ffffffffffL;// 求充电或放电的平均时间public long computeTimePerLevel() {final long[] steps = mStepDurations;// 电池信息的总条数final int numSteps = mNumStepDurations;// For now we'll do a simple average across all steps.if (numSteps <= 0) {return -1;}long total = 0;for (int i=0; i<numSteps; i++) {// total += 0x0203629876543210 & 0x000000ffffffffffL// 充电或放电信息的总时间 += 充电或放电的单条时间total += steps[i] & STEP_LEVEL_TIME_MASK;}// 总时间 / 总记录数 // 因为为 mDischargeStepTracker.computeTimePerLevel,故这里计算出每消耗1%的电量的平均时间return total / numSteps;}
查看下 mStepDurations 的作用
public static final int STEP_LEVEL_LEVEL_SHIFT = 40;public static final long STEP_LEVEL_LEVEL_MASK = 0x0000ff0000000000L;// 例如 电池信息格式 zD-62-9876543210public void decodeEntryAt(int index, String value) {// 获取电池电量// 例如 value = zD-62-9876543210,得到 level = 0x62,即 98% 的电量out |= (level << STEP_LEVEL_LEVEL_SHIFT) & STEP_LEVEL_LEVEL_MASK;long duration = 0;while (i < N && (c=value.charAt(i)) != '-') {i++;duration <<= 4;if (c >= '0' && c <= '9') {duration += c - '0';} else if (c >= 'a' && c <= 'f') {duration += c - 'a' + 10;} else if (c >= 'A' && c <= 'F') {duration += c - 'A' + 10;}}// zD-62-9876543210 对应 0x0203629876543210mStepDurations[index] = out | (duration & STEP_LEVEL_TIME_MASK);}
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