android4.2 添加永不休眠选项

设置 > 显示 > 休眠
a. 
res/values/arrays.xml
    <string-array name="screen_timeout_entries">
        <item>15 seconds</item>
        <item>30 seconds</item>
        <item>1 minute</item>
        <item>2 minutes</item>
        <item>5 minutes</item>
        <item>10 minutes</item>
        <item>30 minutes</item>
        <item>Never </item>
    </string-array>
<!-- AnsonCode 2012.7.4
+ <item>Never </item>
-->
    <!-- Do not translate. -->
    <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>
<!-- AnsonCode
－1 的值在表示永不休眠。
+ <item>-1</item>
-->
b. 
在其它有定义<string-array name="screen_timeout_entries">
的地方添加一行，用于显示不同语言文字的内容，这是为了解决在不同语言时，如果没有定义，会出现异常退出的情况。大概有50个arrays.xml文件需要修改。
如：res/values-zh-rCN/arrays.xml中（此路径中绿色表示国家语言）
  <string-array name="screen_timeout_entries">
    <item msgid="3342301044271143016">"15 秒"</item>
    <item msgid="8881760709354815449">"30 秒"</item>
    <item msgid="7589406073232279088">"1 分钟"</item>
    <item msgid="7001195990902244174">"2 分钟"</item>
    <item msgid="7489864775127957179">"5 分钟"</item>
    <item msgid="2314124409517439288">"10 分钟"</item>
    <item msgid="6864027152847611413">"30 分钟"</item>
    <item msgid="6864027952847611413">"从不"</item>
  </string-array>
c.
在作出以上修改后，主界面的显示会不正常，需要在代码中加以下处理：
找到如下方法：
private void updateTimeoutPreferenceDescription(long currentTimeout) {
        ListPreference preference = mScreenTimeoutPreference;
        String summary;
        if (currentTimeout < -1) {
        //if (currentTimeout < 0) { AnsonCode2012.7.4
            // Unsupported value
            summary = "";
        } else {
            final CharSequence[] entries = preference.getEntries();
            final CharSequence[] values = preference.getEntryValues();
            int best = 0;
            for (int i = 0; i < values.length; i++) {
                long timeout = Long.parseLong(values[i].toString());
                if (currentTimeout == timeout) {
                    best = i;
                    break;AnsonCode2012.7.4
                }
            }
            summary = preference.getContext().getString(R.string.screen_timeout_summary,
                    entries[best]);
            if(currentTimeout < 0)summary = entries[best].toString();//AnsonCode2012.7.4
        }
        preference.setSummary(summary);
    }
//注意与原来代码的区别：
//1） 修改 0 改为－1， 为保证，在界面中，显示的文字不为空。
//2）将 >=改为 ==是作一个准确判断，找到所设定的值便返回，退出循环；
//3）不加此句内容，在界面上会显示： 无操作 从不 后， 加了以后则显示： 从不
//在4.2上稍微有些不同， 主要是修改了对时间值的判断。
    private static final int DEFAULT_SCREEN_OFF_TIMEOUT = 15 * 1000;
    private static final int MINIMUM_SCREEN_OFF_TIMEOUT = 10 * 1000;
    private int getScreenOffTimeoutLocked() {
        int timeout = mScreenOffTimeoutSetting;
        if (isMaximumScreenOffTimeoutFromDeviceAdminEnforcedLocked()) {
            timeout = Math.min(timeout, mMaximumScreenOffTimeoutFromDeviceAdmin);
        }
        if (mUserActivityTimeoutOverrideFromWindowManager >= 0) {
            timeout = (int)Math.min(timeout, mUserActivityTimeoutOverrideFromWindowManager);
        }
        return Math.max(timeout, MINIMUM_SCREEN_OFF_TIMEOUT);
    }
 /**
     * Updates the value of mUserActivitySummary to summarize the user requested
     * state of the system such as whether the screen should be bright or dim.
     * Note that user activity is ignored when the system is asleep.
     *
     * This function must have no other side-effects.
     */
    private void updateUserActivitySummaryLocked(long now, int dirty) {
        // Update the status of the user activity timeout timer.
        if ((dirty & (DIRTY_USER_ACTIVITY | DIRTY_WAKEFULNESS | DIRTY_SETTINGS)) != 0) {
            mHandler.removeMessages(MSG_USER_ACTIVITY_TIMEOUT);
            long nextTimeout = 0;
            if (mWakefulness != WAKEFULNESS_ASLEEP) {
                final int screenOffTimeout = getScreenOffTimeoutLocked();
                final int screenDimDuration = getScreenDimDurationLocked(screenOffTimeout);
                mUserActivitySummary = 0;
                if (mLastUserActivityTime >= mLastWakeTime) {
                    nextTimeout = mLastUserActivityTime
                            + screenOffTimeout - screenDimDuration;
                    if (now < nextTimeout) {
                        mUserActivitySummary |= USER_ACTIVITY_SCREEN_BRIGHT;
                    } else {
                        nextTimeout = mLastUserActivityTime + screenOffTimeout;
                        if (now < nextTimeout) {
                            mUserActivitySummary |= USER_ACTIVITY_SCREEN_DIM;
                        }
                    }
                }
                if (mUserActivitySummary == 0
                        && mLastUserActivityTimeNoChangeLights >= mLastWakeTime) {
                    nextTimeout = mLastUserActivityTimeNoChangeLights + screenOffTimeout;
                    if (now < nextTimeout
                            && mDisplayPowerRequest.screenState
                                    != DisplayPowerRequest.SCREEN_STATE_OFF) {
                        mUserActivitySummary = mDisplayPowerRequest.screenState
                                == DisplayPowerRequest.SCREEN_STATE_BRIGHT ?
                                USER_ACTIVITY_SCREEN_BRIGHT : USER_ACTIVITY_SCREEN_DIM;
                    }
                }
                if (mUserActivitySummary != 0) {
                    Message msg = mHandler.obtainMessage(MSG_USER_ACTIVITY_TIMEOUT);
                    msg.setAsynchronous(true);
                    ///mHandler.sendMessageAtTime(msg, nextTimeout);
          if(mScreenOffTimeoutSetting > 0)mHandler.sendMessageAtTime(msg, nextTimeout);//添加了一行判断, 如果值为-1则不发送广播
                }
            } else {
                mUserActivitySummary = 0;
            }
            if (DEBUG_SPEW) {
                Slog.d(TAG, "updateUserActivitySummaryLocked: mWakefulness="
                        + wakefulnessToString(mWakefulness)
                        + ", mUserActivitySummary=0x" + Integer.toHexString(mUserActivitySummary)
                        + ", nextTimeout=" + TimeUtils.formatUptime(nextTimeout));
            }
        }
    }