android 7.0 Settings 省电模式

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Settings 省电模式:
开启省电方式有两种:
第一种自动开启,点击Turn on automatically,弹出下拉选项,选择never, at 5% battery, at 15% battery
第二种手动开启,点击SwitchBar开关即可设置
先说第一种:

关键字段:

/packages/apps/Settings/res/values/strings.xml    <!-- [CHAR_LIMIT=40] Battery saver: Title for automatic entry option -->    <string name="battery_saver_turn_on_automatically_title">Turn on automatically</string>

对应布局:/packages/apps/Settings/res/xml/battery_saver_settings.xml

控件:        <DropDownPreference            android:key="turn_on_automatically"            android:title="@string/battery_saver_turn_on_automatically_title"            android:summary="%s" />使用类:/packages/apps/Settings/src/com/android/settings/fuelgauge/BatterySaverSettings.java

@Override    public void onActivityCreated(Bundle savedInstanceState) {        super.onActivityCreated(savedInstanceState);        if (mCreated) {            mSwitchBar.show();            return;        }        mCreated = true;        addPreferencesFromResource(R.xml.battery_saver_settings);        mContext = getActivity();        mSwitchBar = ((SettingsActivity) mContext).getSwitchBar();        mSwitch = mSwitchBar.getSwitch();        mSwitchBar.show();        //SettingPref 帮助管理绑定到全局或系统设置的双状态或下拉式首选项, 这里使用下拉选项        mTriggerPref = new SettingPref(SettingPref.TYPE_GLOBAL, KEY_TURN_ON_AUTOMATICALLY,                Global.LOW_POWER_MODE_TRIGGER_LEVEL,                0, /*default*/                getResources().getIntArray(R.array.battery_saver_trigger_values)) { //设置下拉子选项 共3个 (0 5 15)            @Override            protected String getCaption(Resources res, int value) {                if (value > 0 && value < 100) {                    return res.getString(R.string.battery_saver_turn_on_automatically_pct,                                         Utils.formatPercentage(value));                }                return res.getString(R.string.battery_saver_turn_on_automatically_never); //never选项 默认值            }        };        mTriggerPref.init(this); //初始化 mDropDown.setEntries(entries); mDropDown.setEntryValues(values) , 设置点击事件        mPowerManager = (PowerManager) mContext.getSystemService(Context.POWER_SERVICE);    }/**   type    存放类型 两种: global 和 system   key     控件的key   setting Settings数据存放的键   def     DropDownPreference 的默认值   values  DropDownPreference 的下拉选项集合*/public SettingPref(int type, String key, String setting, int def, int... values) {        mType = type;        mKey = key;        mSetting = setting;        mDefault = def;        mValues = values;        mUri = getUriFor(mType, mSetting);    }

在 mTriggerPref.init(this) 方法中设置了DropDownPreference的点击事件

      if (mDropDown != null && p != null) {            p.setOnPreferenceChangeListener(new OnPreferenceChangeListener() {                @Override                public boolean onPreferenceChange(Preference preference, Object newValue) {                   //当下拉选项改变时,将当前选项的值存入Settings数据库其实就是存如入setting_global.xml key值是Global.LOW_POWER_MODE_TRIGGER_LEVEL                    return setSetting(context, Integer.parseInt((String) newValue));                }            });            return mDropDown;        }

当Settings数据库中Global.LOW_POWER_MODE_TRIGGER_LEVEL改变时,在PowerManagerService中做了监听:

/frameworks/base/services/core/java/com/android/server/power/PowerManagerService.javapublic void systemReady(IAppOpsService appOps) {     resolver.registerContentObserver(Settings.Global.getUriFor(             Settings.Global.LOW_POWER_MODE),             false, mSettingsObserver, UserHandle.USER_ALL);     //注册Global.LOW_POWER_MODE_TRIGGER_LEVEL数据改变监听     resolver.registerContentObserver(Settings.Global.getUriFor(             Settings.Global.LOW_POWER_MODE_TRIGGER_LEVEL),             false, mSettingsObserver, UserHandle.USER_ALL);}    private final class SettingsObserver extends ContentObserver {        public SettingsObserver(Handler handler) {            super(handler);        }        @Override        public void onChange(boolean selfChange, Uri uri) {            synchronized (mLock) {                handleSettingsChangedLocked(); //更新省电模式            }        }    }    private void handleSettingsChangedLocked() {        updateSettingsLocked();        updatePowerStateLocked();    }

updateSettingsLocked 和 updatePowerStateLocked 方法中做了一些状态的判断,最后都会调用:
updateLowPowerModeLocked(); //此方法是最终功能实现的地方.

再说第二种:
SwitchBar 开关的监听事件:
使用类:

/packages/apps/Settings/src/com/android/settings/fuelgauge/BatterySaverSettings.javapublic void onResume(){    mSwitchBar.addOnSwitchChangeListener(this); //注册}public void onPause() {    mSwitchBar.removeOnSwitchChangeListener(this); //删除}

监听事件的处理:

@Override    public void onSwitchChanged(Switch switchView, boolean isChecked) {        mHandler.removeCallbacks(mStartMode);        if (isChecked) {            mHandler.postDelayed(mStartMode, WAIT_FOR_SWITCH_ANIM); //开启省电模式  mStartMode是一个Runnable        } else {            if (DEBUG) Log.d(TAG, "Stopping low power mode from settings");            trySetPowerSaveMode(false);        }    }

最后调用:

private void trySetPowerSaveMode(boolean mode) {        if (!mPowerManager.setPowerSaveMode(mode)) { //PowerManager 实际调用的是PowerManagerService的方法            if (DEBUG) Log.d(TAG, "Setting mode failed, fallback to current value");            mHandler.post(mUpdateSwitch);        }        // TODO: Remove once broadcast is in place.        ConditionManager.get(getContext()).getCondition(BatterySaverCondition.class).refreshState();    }

实际调用: PowerManagerService --> setPowerSaveMode()
PowerManagerService.java

@Override // Binder call        public boolean setPowerSaveMode(boolean mode) {            mContext.enforceCallingOrSelfPermission(                    android.Manifest.permission.DEVICE_POWER, null);            final long ident = Binder.clearCallingIdentity();            try {                return setLowPowerModeInternal(mode);             } finally {                Binder.restoreCallingIdentity(ident);            }        }    private boolean setLowPowerModeInternal(boolean mode) {        synchronized (mLock) {            if (DEBUG) Slog.d(TAG, "setLowPowerModeInternal " + mode + " mIsPowered=" + mIsPowered);            if (mIsPowered) {                return false;            }            Settings.Global.putInt(mContext.getContentResolver(),                    Settings.Global.LOW_POWER_MODE, mode ? 1 : 0);  //将开关状态存入数据库            mLowPowerModeSetting = mode;            if (mAutoLowPowerModeConfigured && mBatteryLevelLow) {                if (mode && mAutoLowPowerModeSnoozing) {                    if (DEBUG_SPEW) {                        Slog.d(TAG, "setLowPowerModeInternal: clearing low power mode snooze");                    }                    mAutoLowPowerModeSnoozing = false;                } else if (!mode && !mAutoLowPowerModeSnoozing) {                    if (DEBUG_SPEW) {                        Slog.d(TAG, "setLowPowerModeInternal: snoozing low power mode");                    }                    mAutoLowPowerModeSnoozing = true;                }            }            updateLowPowerModeLocked(); //更新状态            return true;        }    }

最后说一下updateLowPowerModeLocked()方法:

//此方法返回true，表示省电模式设置成功private void updateLowPowerModeLocked() {                   if ((mIsPowered || !mBatteryLevelLow && !mBootCompleted) && mLowPowerModeSetting) {            if (DEBUG_SPEW) {                Slog.d(TAG, "updateLowPowerModeLocked: powered or booting with sufficient battery,"                        + " turning setting off");            }            // Turn setting off if powered            Settings.Global.putInt(mContext.getContentResolver(),                    Settings.Global.LOW_POWER_MODE, 0);            mLowPowerModeSetting = false;        }        /** mIsPowered 变量表示充电状态，true表示正在充电（已接入电源），否则为false            mLowPowerModeSetting 变量（表示设置低电模式的当前状态；从系统设置中获取的值，即数据库字段“low_power”的值）            mAutoLowPowerModeConfigured 自动开启省电模式的当前状态，即数据库字段“low_power_trigger_level”是否为0的值；不为0时表示打开了自动开                                        启功能，该变量为true            mAutoLowPowerModeSnoozing 当电量低并且允许自动设置省电模式时，如果此时省电模式是开启的，就要设置mAutoLowPowerModeSnoozing的值为                                      false；如果省电模式是关闭的，就要设置mAutoLowPowerModeSnoozing的值为true。就是要求                                      mAutoLowPowerModeSnoozing变量与省电模式的逻辑保持一致。            mBatteryLevelLow  如果电池电量低为true,否则为false            mBatteryLevelLowValue 当前自动开启省电模式的电量百分比,就是前面DropDownPreference中设置的values值,0(never) 5% 15%            */        final boolean autoLowPowerModeEnabled = !mIsPowered && mAutoLowPowerModeConfigured                && !mAutoLowPowerModeSnoozing && mBatteryLevelLow &&                (mBatteryManagerInternal.getBatteryLevel() <= mBatteryLevelLowValue);                final boolean lowPowerModeEnabled = mLowPowerModeSetting || autoLowPowerModeEnabled;        if (mLowPowerModeEnabled != lowPowerModeEnabled) {            mLowPowerModeEnabled = lowPowerModeEnabled;            powerHintInternal(POWER_HINT_LOW_POWER, lowPowerModeEnabled ? 1 : 0);            postAfterBootCompleted(new Runnable() {                @Override                public void run() {                       //发送处理广播 ACTION_POWER_SAVE_MODE_CHANGING                    Intent intent = new Intent(PowerManager.ACTION_POWER_SAVE_MODE_CHANGING)                            .putExtra(PowerManager.EXTRA_POWER_SAVE_MODE, mLowPowerModeEnabled)                            .addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);                    mContext.sendBroadcast(intent);                    ArrayList<PowerManagerInternal.LowPowerModeListener> listeners;                    synchronized (mLock) {                        listeners = new ArrayList<PowerManagerInternal.LowPowerModeListener>(                                mLowPowerModeListeners);                    }                    for (int i=0; i<listeners.size(); i++) {                        listeners.get(i).onLowPowerModeChanged(lowPowerModeEnabled);                    }                       //发送ACTION_POWER_SAVE_MODE_CHANGED广播，更新省电模式状态                    intent = new Intent(PowerManager.ACTION_POWER_SAVE_MODE_CHANGED);                    intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);                    mContext.sendBroadcast(intent);                    // Send internal version that requires signature permission.                    mContext.sendBroadcastAsUser(new Intent(                            PowerManager.ACTION_POWER_SAVE_MODE_CHANGED_INTERNAL), UserHandle.ALL,                            Manifest.permission.DEVICE_POWER);                }            });        }    }

"ACTION_POWER_SAVE_MODE_CHANGING" 广播的接收类:
/frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/policy/BatteryControllerImpl.java
/frameworks/base/packages/SystemUI/src/com/android/systemui/power/PowerUI.java

"ACTION_POWER_SAVE_MODE_CHANGED" 广播的接收类:
/frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/policy/BatteryControllerImpl.java
/frameworks/base/packages/SystemUI/src/com/android/systemui/power/PowerUI.java
/frameworks/base/services/voiceinteraction/java/com/android/server/soundtrigger/SoundTriggerHelper.java
/frameworks/base/services/core/java/com/android/server/location/GnssLocationProvider.java
在对应的BroadcastReceiver中处理相关逻辑,比如: 降低屏幕亮度关闭GPS功能关闭语音识别等.

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