Android4.4 SystemUI分析之PowerUI

以下分析是基于MTK Android4.4原生的SystemUI与Google 的SystemUI有微小的区别，但两者的整体框架是差不多的。

这一篇是分析SystemUI的第一篇，先从最简单的PowerUI着手，源码路径：/frameworks/base/packages/SystemUI  程序目录结构如下：

我导入Eclipse编辑，报错的原因是因为找不到Framework上的一些包和资源，这个没有关系；修改完后在使用mmm模块编译，再push到手机（eng版本）上进行调试，push后需要重启才能生效。

在AndroidManifest.xml上没有Activity注册

<intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>

    static final void startSystemUi(Context context) {
        Intent intent = new Intent();
        intent.setComponent(new ComponentName("com.android.systemui",
                    "com.android.systemui.SystemUIService"));
        //Slog.d(TAG, "Starting service: " + intent);
        context.startServiceAsUser(intent, UserHandle.OWNER);
    }

SystemUIService的关键代码如下：

package com.android.systemui;

import android.app.Service;
import android.content.Intent;
import android.content.res.Configuration;
import android.os.IBinder;
import android.util.Log;

import java.io.FileDescriptor;
import java.io.PrintWriter;
import java.util.HashMap;

public class SystemUIService extends Service {
    private static final String TAG = "SystemUIService";

    /**
     * The classes of the stuff to start.
     */
    private final Class<?>[] SERVICES = new Class[] {
            com.android.systemui.recent.Recents.class,
            com.android.systemui.statusbar.SystemBars.class,
            com.android.systemui.usb.StorageNotification.class,
            com.android.systemui.power.PowerUI.class,
            com.android.systemui.media.RingtonePlayer.class,
            com.android.systemui.settings.SettingsUI.class,
        };

    /**
     * Hold a reference on the stuff we start.
     */
    private final SystemUI[] mServices = new SystemUI[SERVICES.length];

    @Override
    public void onCreate() {
        HashMap<Class<?>, Object> components = new HashMap<Class<?>, Object>();
        final int N = SERVICES.length;
        for (int i=0; i<N; i++) {
            Class<?> cl = SERVICES[i];
            Log.d(TAG, "loading: " + cl);
            Log.d("dzt", "loading: " + cl);
            try {
                mServices[i] = (SystemUI)cl.newInstance();
            } catch (IllegalAccessException ex) {
                throw new RuntimeException(ex);
            } catch (InstantiationException ex) {
                throw new RuntimeException(ex);
            }
            mServices[i].mContext = this;
            mServices[i].mComponents = components;
            Log.d(TAG, "running: " + mServices[i]);
            Log.d("dzt", "running: " + mServices[i]);
            mServices[i].start();
        }
    }
}

com.android.systemui.recent.Recents.class,
            com.android.systemui.statusbar.SystemBars.class,
            com.android.systemui.usb.StorageNotification.class,
            com.android.systemui.power.PowerUI.class,
            com.android.systemui.media.RingtonePlayer.class,
            com.android.systemui.settings.SettingsUI.class,

下面就分析最简单的com.android.systemui.power.PowerUI.class

在PowerUI的start()方法中，注册一些监听器

public void start() {

        mLowBatteryAlertCloseLevel = mContext.getResources().getInteger(
                com.android.internal.R.integer.config_lowBatteryCloseWarningLevel);
        mLowBatteryReminderLevels[0] = mContext.getResources().getInteger(
                com.android.internal.R.integer.config_lowBatteryWarningLevel);
        mLowBatteryReminderLevels[1] = mContext.getResources().getInteger(
                com.android.internal.R.integer.config_criticalBatteryWarningLevel);

        final PowerManager pm = (PowerManager) mContext.getSystemService(Context.POWER_SERVICE);
        mScreenOffTime = pm.isScreenOn() ? -1 : SystemClock.elapsedRealtime();

        // Register for Intent broadcasts for...
        IntentFilter filter = new IntentFilter();
        filter.addAction(Intent.ACTION_BATTERY_CHANGED);
        filter.addAction(Intent.ACTION_SCREEN_OFF);
        filter.addAction(Intent.ACTION_SCREEN_ON);
        /// M: Support show battery level when configuration changed. @{
        filter.addAction(Intent.ACTION_CONFIGURATION_CHANGED);
        /// M: Support show battery level when configuration changed. @}
        /// M: Hide low battery dialog when PowerOffAlarm ring. @{
        filter.addAction("android.intent.action.normal.boot");
        filter.addAction("android.intent.action.ACTION_SHUTDOWN_IPO");
        /// M: Hide low battery dialog when PowerOffAlarm ring. @}
        mContext.registerReceiver(mIntentReceiver, filter, null, mHandler);
    }