Settings-battery

电池界面

一：onCreate()

 @Override
    public void onCreate(Bundle icicle) {
        super.onCreate(icicle);
        mStatsHelper.create(icicle);

        addPreferencesFromResource(R.xml.power_usage_summary);加载布局
        mAppListGroup = (PreferenceGroup) findPreference(KEY_APP_LIST);//实例化group
        mBatteryStatusPref = mAppListGroup.findPreference(KEY_BATTERY_STATUS);
        setHasOptionsMenu(true);

		getActivity().getActionBar().setDisplayHomeAsUpEnabled(false);
		getActivity().getActionBar().setHomeButtonEnabled(false);
			
    }

二：看XML文件

<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"
        android:title="@string/battery_since_unplugged"
        android:key="app_list">
    <Preference
        style="?android:attr/preferenceInformationStyle"
        android:key="battery_status"
        android:persistent="false"
    />
</PreferenceScreen>

三：走onCreateView

@Override
	public View onCreateView(LayoutInflater inflater, ViewGroup container,
				Bundle savedInstanceState) {
		View v = inflater.inflate(R.layout.add_layout_preference,null);
		return v;		
	}

四：单机事件onPreferenceTreeClick<pre name="code" class="java">@Override
    public boolean onPreferenceTreeClick(PreferenceScreen preferenceScreen, Preference preference) {
        if (preference instanceof BatteryHistoryPreference) {
            Parcel hist = Parcel.obtain();
            mStatsHelper.getStats().writeToParcelWithoutUids(hist, 0);
            byte[] histData = hist.marshall();
            Bundle args = new Bundle();
            args.putByteArray(BatteryHistoryDetail.EXTRA_STATS, histData);
            PreferenceActivity pa = (PreferenceActivity)getActivity();
            pa.startPreferencePanel(BatteryHistoryDetail.class.getName(), args,
                    R.string.history_details_title, null, null, 0);
            return super.onPreferenceTreeClick(preferenceScreen, preference);
        }
        if (!(preference instanceof PowerGaugePreference)) {
            return false;
        }
        PowerGaugePreference pgp = (PowerGaugePreference) preference;
        BatterySipper sipper = pgp.getInfo();
        mStatsHelper.startBatteryDetailPage((PreferenceActivity) getActivity(), sipper, true);
        return super.onPreferenceTreeClick(preferenceScreen, preference);
    

五：数据来源onResume()

 @Override
    public void onResume() {
        super.onResume();
        getActivity().registerReceiver(mBatteryInfoReceiver,
                new IntentFilter(Intent.ACTION_BATTERY_CHANGED));
        refreshStats();
    }

private void refreshStats() {
        mAppListGroup.removeAll();
        mAppListGroup.setOrderingAsAdded(false);

        mBatteryStatusPref.setOrder(-2);
        mAppListGroup.addPreference(mBatteryStatusPref);
        BatteryHistoryPreference hist = new BatteryHistoryPreference(
                getActivity(), mStatsHelper.getStats());
        hist.setOrder(-1);
        mAppListGroup.addPreference(hist);

        if (mStatsHelper.getPowerProfile().getAveragePower(
                PowerProfile.POWER_SCREEN_FULL) < 10) {
            addNotAvailableMessage();
            return;
        }
        mStatsHelper.refreshStats(false);
        List<BatterySipper> usageList = mStatsHelper.getUsageList();
        for (BatterySipper sipper : usageList) {
            if (sipper.getSortValue() < MIN_POWER_THRESHOLD) continue;
            final double percentOfTotal =
                    ((sipper.getSortValue() / mStatsHelper.getTotalPower()) * 100);
            if (percentOfTotal < 1) continue;
            PowerGaugePreference pref =
                    new PowerGaugePreference(getActivity(), sipper.getIcon(), sipper);
            final double percentOfMax =
                    (sipper.getSortValue() * 100) / mStatsHelper.getMaxPower();
            sipper.percent = percentOfTotal;
            pref.setTitle(sipper.name);
            pref.setOrder(Integer.MAX_VALUE - (int) sipper.getSortValue()); // Invert the order
            pref.setPercent(percentOfMax, percentOfTotal);
            if (sipper.uidObj != null) {
                pref.setKey(Integer.toString(sipper.uidObj.getUid()));
            }
            mAppListGroup.addPreference(pref);
            if (mAppListGroup.getPreferenceCount() > (MAX_ITEMS_TO_LIST+1)) break;
        }