Android5.1 手機Settings加入從不休眠

Settings的apk的目錄是在packages\apps\Settings下，由於我們添加的從不休眠是在顯示項裏面，所以我們就直接看DisplaySettings.Java的代碼了。

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    final Activity activity = getActivity();
    final ContentResolver resolver = activity.getContentResolver();
入display_settings的Preferences
    addPreferencesFromResource(R.xml.display_settings);

    mScreenSaverPreference = findPreference(KEY_SCREEN_SAVER);
    if (mScreenSaverPreference != null
            && getResources().getBoolean(
                    com.android.internal.R.bool.config_dreamsSupported) == false) {
        getPreferenceScreen().removePreference(mScreenSaverPreference);
    }
到屏幕休眠時間的ListPreference
    mScreenTimeoutPreference = (ListPreference) findPreference(KEY_SCREEN_TIMEOUT);
    final long currentTimeout = Settings.System.getLong(resolver, SCREEN_OFF_TIMEOUT,//從settings數據庫中獲取屏幕休眠時間
            FALLBACK_SCREEN_TIMEOUT_VALUE);
    //mScreenTimeoutPreference.setValue(String.valueOf(currentTimeout));
    //
    long timeoutValue = (currentTimeout == Integer.MAX_VALUE) ? -1 : currentTimeout;//如果從數據庫得到最大值，改成-1
    mScreenTimeoutPreference.setValue(String.valueOf(timeoutValue));
    //
    mScreenTimeoutPreference.setOnPreferenceChangeListener(this);//監聽變化
    disableUnusableTimeouts(mScreenTimeoutPreference);
    //updateTimeoutPreferenceDescription(currentTimeout);
    updateTimeoutPreferenceDescription(timeoutValue);//更新屏幕上的信息

我們先看下display_settings.xml文件中screen_timeout這個ListPreference；

<ListPreference
        android:key="screen_timeout"
        android:title="@string/screen_timeout"
        android:summary="@string/screen_timeout_summary"
        android:persistent="false"
        android:entries="@array/screen_timeout_entries"
        android:entryValues="@array/screen_timeout_values" />

接下來我們看下updateTimeoutPreferenceDescription這個函數，這個函數最後調用preference.setSummary主要更新屏幕上的信息

private void updateTimeoutPreferenceDescription(long currentTimeout) {
    ListPreference preference = mScreenTimeoutPreference;
    String summary;
    if (currentTimeout == -1) {//如果爲-1，string爲永不
        // Unsupported value
        summary = preference.getContext().getString(R.string.screen_never_timeout_summary);
    } else if (currentTimeout < -1) {
        // Unsupported value
        summary = "";
    } else {
        final CharSequence[] entries = preference.getEntries();
        final CharSequence[] values = preference.getEntryValues();
        if (entries == null || entries.length == 0) {
            summary = "";
        } else {
            int best = 0;
            for (int i = 0; i < values.length; i++) {
                long timeout = Long.parseLong(values[i].toString());
                /*if (currentTimeout >= timeout) {
                    best = i;
                }*/
                if (currentTimeout >= timeout && timeout > 0) {//timeout爲了過濾-1
                    best = i;
                }
            }
            summary = preference.getContext().getString(R.string.screen_timeout_summary,
                    entries[best]);
        }
    }
    preference.setSummary(summary);
}

先看下R.string.screen_timeout_summary這個string

<string name="screen_timeout_summary" msgid="327761329263064327">"無操作<xliff:g id="TIMEOUT_DESCRIPTION">%1$s</xliff:g>後"</string>

可以看下dream_timeout_entries的xml文件

<string-array name="dream_timeout_entries">
  <item msgid="3149294732238283185">"永不"</item>
  <item msgid="2194151041885903260">"15 秒"</item>
  <item msgid="5892295237131074341">"30 秒"</item>
  <item msgid="3538441365970038213">"1 分鐘"</item>
  <item msgid="412343871668955639">"2 分鐘"</item>
  <item msgid="5076853889688991690">"5 分鐘"</item>
  <item msgid="1903860996174927898">"10 分鐘"</item>
  <item msgid="6415509612413178727">"30 分鐘"</item>
</string-array>

因此兩者組合起來會有"無操作5分鐘後"，這樣的效果。

另外onPreferenceChange這個函數，是當你選擇選項變化時調用。

public boolean onPreferenceChange(Preference preference, Object objValue) {
    final String key = preference.getKey();
    if (KEY_SCREEN_TIMEOUT.equals(key)) {//當時屏幕休眠時間那一項改變
        /*try {
            int value = Integer.parseInt((String) objValue);
            Settings.System.putInt(getContentResolver(), SCREEN_OFF_TIMEOUT, value);
            Log.e(TAG, "DisplaySettings:currentTimeout:" + value);
            updateTimeoutPreferenceDescription(value);
        } catch (NumberFormatException e) {
            Log.e(TAG, "could not persist screen timeout setting", e);
        }*/
        int value = Integer.parseInt((String) objValue);// 先獲取值
        int oldvalue = Integer.parseInt(((ListPreference)preference).getValue());
        if (value != oldvalue) {
            int timeoutValue = ( -1 == value) ? Integer.MAX_VALUE : value;//如果值爲-1，變爲最大值
            try {
                Log.e(TAG, "timeoutValue is: " + timeoutValue);
                Settings.System.putInt(getContentResolver(), SCREEN_OFF_TIMEOUT, timeoutValue);//保存到settings這個數據庫中
                updateTimeoutPreferenceDescription(value);//更新顯示部分
            } catch (NumberFormatException e) {
                Log.e(TAG, "could not persist screen timeout setting", e);
            }
        }
    }
    if (KEY_FONT_SIZE.equals(key)) {
        writeFontSizePreference(objValue);
    }
    if (preference == mAutoBrightnessPreference) {
        boolean auto = (Boolean) objValue;
        Settings.System.putInt(getContentResolver(), SCREEN_BRIGHTNESS_MODE,
                auto ? SCREEN_BRIGHTNESS_MODE_AUTOMATIC : SCREEN_BRIGHTNESS_MODE_MANUAL);
    }
    if (preference == mLiftToWakePreference) {
        boolean value = (Boolean) objValue;
        Settings.Secure.putInt(getContentResolver(), WAKE_GESTURE_ENABLED, value ? 1 : 0);
    }
    if (preference == mDozePreference) {
        boolean value = (Boolean) objValue;
        Settings.Secure.putInt(getContentResolver(), DOZE_ENABLED, value ? 1 : 0);
    }
    return true;
}

我們可以看下screen_timeout_values的xml文件，在最後面添加了一個-1，也就是當選擇"永不“的時候會傳入一個-1，這時候會變成一個Integer.MAX_VALUE 存數據庫。

<string-array name="screen_timeout_values" translatable="false">
    <!-- Do not translate. -->
    <item>15000</item>
    <!-- Do not translate. -->
    <item>30000</item>
    <!-- Do not translate. -->
    <item>60000</item>
    <!-- Do not translate. -->
    <item>120000</item>
    <!-- Do not translate. -->
    <item>300000</item>
    <!-- Do not translate. -->
    <item>600000</item>
    <!-- Do not translate. -->
    <item>1800000</item>
    <item>-1</item>
</string-array>

這樣就完成了在settings中添加永不休眠這個功能。

下面我們再來看下PowerManagerService中如何將settings添加的這個功能生效。

在PowerManagerService中的systemReady函數中註冊了對settings數據庫SCREEN_OFF_TIMEOUT的監聽

resolver.registerContentObserver(Settings.System.getUriFor(
        Settings.System.SCREEN_OFF_TIMEOUT),
        false, mSettingsObserver, UserHandle.USER_ALL);

而mSettingsObserver的類如下：

private final class SettingsObserver extends ContentObserver {
    public SettingsObserver(Handler handler) {
        super(handler);
    }

    @Override
    public void onChange(boolean selfChange, Uri uri) {
        synchronized (mLock) {
            handleSettingsChangedLocked();
        }
    }
}

再看handleSettingsChangedLocked函數：

private void handleSettingsChangedLocked() {
    updateSettingsLocked();
    updatePowerStateLocked();
}

private void updateSettingsLocked() {
    final ContentResolver resolver = mContext.getContentResolver();

    mDreamsEnabledSetting = (Settings.Secure.getIntForUser(resolver,
            Settings.Secure.SCREENSAVER_ENABLED,
            mDreamsEnabledByDefaultConfig ? 1 : 0,
            UserHandle.USER_CURRENT) != 0);
    mDreamsActivateOnSleepSetting = (Settings.Secure.getIntForUser(resolver,
            Settings.Secure.SCREENSAVER_ACTIVATE_ON_SLEEP,
            mDreamsActivatedOnSleepByDefaultConfig ? 1 : 0,
            UserHandle.USER_CURRENT) != 0);
    mDreamsActivateOnDockSetting = (Settings.Secure.getIntForUser(resolver,
            Settings.Secure.SCREENSAVER_ACTIVATE_ON_DOCK,
            mDreamsActivatedOnDockByDefaultConfig ? 1 : 0,
            UserHandle.USER_CURRENT) != 0);
    mScreenOffTimeoutSetting = Settings.System.getIntForUser(resolver,
            Settings.System.SCREEN_OFF_TIMEOUT, DEFAULT_SCREEN_OFF_TIMEOUT,
            UserHandle.USER_CURRENT);//獲取settings數據庫中SCREEN_OFF_TIMEOUT的值

更新了mScreenOffTimeoutSetting之後，會去調用updatePowerStateLocked函數，更新整個PowerManagerService的狀態：

通過在updateUserActivitySummaryLocked函數中調用getScreenOffTimeoutLocked函數：

private void updateUserActivitySummaryLocked(long now, int dirty) {
    // Update the status of the user activity timeout timer.
    if ((dirty & (DIRTY_WAKE_LOCKS | DIRTY_USER_ACTIVITY
            | DIRTY_WAKEFULNESS | DIRTY_SETTINGS)) != 0) {
        mHandler.removeMessages(MSG_USER_ACTIVITY_TIMEOUT);

        long nextTimeout = 0;
        if (mWakefulness == WAKEFULNESS_AWAKE
                || mWakefulness == WAKEFULNESS_DREAMING
                || mWakefulness == WAKEFULNESS_DOZING) {
            final int sleepTimeout = getSleepTimeoutLocked();
            final int screenOffTimeout = getScreenOffTimeoutLocked(sleepTimeout);//調用getScreenOffTimeoutLocked函數
            final int screenDimDuration = getScreenDimDurationLocked(screenOffTimeout);

在getScreenOffTimeoutLocked函數中用mScreenOffTimeoutSetting這個成員變量：

2,若是android5.0的code,請在前面的修改基礎上再修改下面的代碼：

frameworks/base/services/core/java/com/android/server/power/PowerManagerService.java

 private int getScreenOffTimeoutLocked(int sleepTimeout) {

        if (sleepTimeout >= 0) {
            timeout = Math.min(timeout, sleepTimeout);
            Slog.d("TAG", "..33333333..sendMessageAtTime");

        }

//add_begin

        if(timeout < 0 ){
            timeout = Integer.MAX_VALUE ;

        }

//add_end

        if (mUserActivityTimeoutMin) {
            timeout = (int)Math.min(timeout, mUserActivityTimeoutOverrideFromCMD);
        }
        return Math.max(timeout, mMinimumScreenOffTimeoutConfig);
    }

private int getScreenOffTimeoutLocked(int sleepTimeout) {
    int timeout = mScreenOffTimeoutSetting;
    if (isMaximumScreenOffTimeoutFromDeviceAdminEnforcedLocked()) {
        timeout = Math.min(timeout, mMaximumScreenOffTimeoutFromDeviceAdmin);
    }
    if (mUserActivityTimeoutOverrideFromWindowManager >= 0) {
        timeout = (int)Math.min(timeout, mUserActivityTimeoutOverrideFromWindowManager);
    }
    if (sleepTimeout >= 0) {
        timeout = Math.min(timeout, sleepTimeout);
    }
    return Math.max(timeout, mMinimumScreenOffTimeoutConfig);
}