Android 4.0 ICS SystemUI浅析——StatusBar加载流程分析

  前面两篇文章《 Android 4.0 ICS SystemUI浅析——SystemUI启动流程 》、《 Android 4.0 ICS SystemUI浅析——StatusBar结构分析 》SystemUI和StatusBar的冰山一角，那么本文将从代码的角度来分析StatusBar的加载流程。

       本文来自： http://blog.csdn.net/yihongyuelan  欢迎转载 请务必注明出处！

        在《 Android 4.0 ICS SystemUI浅析——SystemUI启动流程 》中，我们提到了在Phone中，整个StatusBar和NavigationBar都是在/SourceCode/frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java的start()方法中，完成初始化并显示到界面上的。因此，我们回到这段代码中查看：

@Override    public void start() {        mDisplay = ((WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE))                .getDefaultDisplay();        mWindowManager = IWindowManager.Stub.asInterface(                ServiceManager.getService(Context.WINDOW_SERVICE));        super.start(); // calls makeStatusBarView() 这里会调用父类StatusBar.java中的start()方法        addNavigationBar();//加载导航栏，本文因以StatusBar为主，因此暂不分析NavigationBar        //addIntruderView();        // Lastly, call to the icon policy to install/update all the icons.        mIconPolicy = new PhoneStatusBarPolicy(mContext);//用于初始化以及更新StatusBar上的icons    }

       我们继续跟踪super.start()方法，来到/SourceCode/frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/StatusBar.java的start()方法中，如代码所示：

public void start() {        // First set up our views and stuff.首先准备我们需要显示的view以及原材料        //我们先跟踪这里的makeStatusBarView        View sb = makeStatusBarView();        // Connect in to the status bar manager service        StatusBarIconList iconList = new StatusBarIconList();        ArrayList<IBinder> notificationKeys = new ArrayList<IBinder>();        ArrayList<StatusBarNotification> notifications = new ArrayList<StatusBarNotification>();       ... ...    }

       通过Open Implementation跳转到makeStatusBarView的实现，因为我们是针对Phone来分析的，因此选择PhoneStatusBar，代码如下：

// ================================================================================    // Constructing the view    // ================================================================================    protected View makeStatusBarView() {        final Context context = mContext;        Resources res = context.getResources();        //获取ExpandedView的尺寸        updateDisplaySize(); // populates mDisplayMetrics        //定义icon的大小，缩放率和彼此间距        loadDimens();        mIconSize = res.getDimensionPixelSize(com.android.internal.R.dimen.status_bar_icon_size);        //设置ExpandedView的布局        ExpandedView expanded = (ExpandedView)View.inflate(context,                R.layout.status_bar_expanded, null);        if (DEBUG) {            expanded.setBackgroundColor(0x6000FF80);        }        expanded.mService = this;        //前面已注释，以下三段代码没有用到        mIntruderAlertView = View.inflate(context, R.layout.intruder_alert, null);        mIntruderAlertView.setVisibility(View.GONE);        mIntruderAlertView.setClickable(true);        PhoneStatusBarView sb;        //这里根据是否是双卡来加载不同的布局文件        if (TelephonyManager.getDefault().isMultiSimEnabled()) {            sb = (PhoneStatusBarView)View.inflate(context,                    R.layout.msim_status_bar, null);        } else {            sb = (PhoneStatusBarView)View.inflate(context,                    R.layout.status_bar, null);        }        sb.mService = this;        mStatusBarView = sb;        //是否显示NavigationBar        try {            boolean showNav = mWindowManager.hasNavigationBar();            if (showNav) {                mNavigationBarView =                    (NavigationBarView) View.inflate(context, R.layout.navigation_bar, null);                mNavigationBarView.setDisabledFlags(mDisabled);            }        } catch (RemoteException ex) {            // no window manager? good luck with that        }        // figure out which pixel-format to use for the status bar.        mPixelFormat = PixelFormat.OPAQUE;        //系统状态图标布局初始化        mStatusIcons = (LinearLayout)sb.findViewById(R.id.statusIcons);        //通知图标布局初始化        mNotificationIcons = (IconMerger)sb.findViewById(R.id.notificationIcons);        mMoreIcon = sb.findViewById(R.id.moreIcon);        mNotificationIcons.setOverflowIndicator(mMoreIcon);        //icons布局初始化，该布局用于装载除开tiker外的所有控件        mIcons = (LinearLayout)sb.findViewById(R.id.icons);        //ticker布局初始化        mTickerView = sb.findViewById(R.id.ticker);        //以上几个重要布局的关系在上一篇文章有详细分析        //以下几段代码是在设置ExpandedView，ExpandedDialog通过加载ExpandedView显示，其中包括了ExpanedView上的清除按钮，        //设置按钮，滚动条，日期显示等等        mExpandedDialog = new ExpandedDialog(context);        mExpandedView = expanded;        mPile = (NotificationRowLayout)expanded.findViewById(R.id.latestItems);        mExpandedContents = mPile; // was: expanded.findViewById(R.id.notificationLinearLayout);        mNoNotificationsTitle = (TextView)expanded.findViewById(R.id.noNotificationsTitle);        mNoNotificationsTitle.setVisibility(View.GONE); // disabling for now        mClearButton = expanded.findViewById(R.id.clear_all_button);        mClearButton.setOnClickListener(mClearButtonListener);        mClearButton.setAlpha(0f);        mClearButton.setEnabled(false);        mDateView = (DateView)expanded.findViewById(R.id.date);        mSettingsButton = expanded.findViewById(R.id.settings_button);        mSettingsButton.setOnClickListener(mSettingsButtonListener);        mScrollView = (ScrollView)expanded.findViewById(R.id.scroll);        //tickerView的初始化        mTicker = new MyTicker(context, sb);        TickerView tickerView = (TickerView)sb.findViewById(R.id.tickerText);        tickerView.mTicker = mTicker;        //TrackingView初始化        mTrackingView = (TrackingView)View.inflate(context, R.layout.status_bar_tracking, null);        mTrackingView.mService = this;        mCloseView = (CloseDragHandle)mTrackingView.findViewById(R.id.close);        mCloseView.mService = this;        mEdgeBorder = res.getDimensionPixelSize(R.dimen.status_bar_edge_ignore);        // set the inital view visibility        setAreThereNotifications();        // Other icons        //以下是对其他icons的加载(信号及电量图标的加载)        mLocationController = new LocationController(mContext); // will post a notification        mBatteryController = new BatteryController(mContext);        mBatteryController.addIconView((ImageView)sb.findViewById(R.id.battery));        SignalClusterView signalCluster;        LinearLayout mSimSignalView;        //根据是否是双卡加载不同的布局文件        if (TelephonyManager.getDefault().isMultiSimEnabled()) {            mMSimNetworkController = new MSimNetworkController(mContext);            mSimSignalView = (LinearLayout) sb.findViewById(R.id.msim_signal_cluster);            if (FeatureQuery.FEATURE_ANNUCIATOR_NEW_STATUSBAR_STYLE) {                CUMSimSignalClusterView cuMSimSignalCluster = (CUMSimSignalClusterView)View.inflate(context, R.layout.msim_signal_cluster_view_cu, null);                mSimSignalView.addView(cuMSimSignalCluster);                for (int i=0; i < TelephonyManager.getDefault().getPhoneCount(); i++) {                    mMSimNetworkController.addSignalCluster(cuMSimSignalCluster, i);                }                cuMSimSignalCluster.setNetworkController(mMSimNetworkController);            } else {                MSimSignalClusterView mSimSignalCluster = (MSimSignalClusterView)View.inflate(context, R.layout.msim_signal_cluster_view, null);                mSimSignalView.addView(mSimSignalCluster);                for (int i=0; i < TelephonyManager.getDefault().getPhoneCount(); i++) {                    mMSimNetworkController.addSignalCluster(mSimSignalCluster, i);                }                mSimSignalCluster.setNetworkController(mMSimNetworkController);            }        } else {            mNetworkController = new NetworkController(mContext);            signalCluster = (SignalClusterView)sb.findViewById(R.id.signal_cluster);            mNetworkController.addSignalCluster(signalCluster);            signalCluster.setNetworkController(mNetworkController);//          final ImageView wimaxRSSI =//                  (ImageView)sb.findViewById(R.id.wimax_signal);//          if (wimaxRSSI != null) {//              mNetworkController.addWimaxIconView(wimaxRSSI);//          }        }        // Recents Panel        //最近使用界面初始化        mRecentTasksLoader = new RecentTasksLoader(context);        updateRecentsPanel();        // receive broadcasts        //注册广播监听器        IntentFilter filter = new IntentFilter();        filter.addAction(Intent.ACTION_CONFIGURATION_CHANGED);        filter.addAction(Intent.ACTION_CLOSE_SYSTEM_DIALOGS);        filter.addAction(Intent.ACTION_SCREEN_ON);        filter.addAction(Intent.ACTION_SCREEN_OFF);        context.registerReceiver(mBroadcastReceiver, filter);        return sb;    }

        通过makeStatusBarView()我们可以看到，在该方法中整个StatusBar根据获取的设备配置信息进行了布局，就好比我们去吃饭，先要安排好座位和桌子，最后才上菜，我们需要加载的icons——就是菜！！:D

        我们回到StatusBar.java的start()方法中继续分析，代码如下：

public void start() {        // First set up our views and stuff.首先准备我们需要显示的view以及原材料        //我们先跟踪这里的makeStatusBarView        View sb = makeStatusBarView();        // Connect in to the status bar manager service        //初始化各个存储器，用于存储各类信息，这些信息通过StatusBarManagerService获取        //iconsList用于存放icons        StatusBarIconList iconList = new StatusBarIconList();        //nodificationKeys保存以Binder为Key的notification        ArrayList<IBinder> notificationKeys = new ArrayList<IBinder>();        //保存StatusBarNotification类型的notifications        ArrayList<StatusBarNotification> notifications = new ArrayList<StatusBarNotification>();        //mCommandQueue是和IStatusBarService进行交互的IBinder        mCommandQueue = new CommandQueue(this, iconList);        //这里实际上获取的是StatusBarManagerService        mBarService = IStatusBarService.Stub.asInterface(                ServiceManager.getService(Context.STATUS_BAR_SERVICE));        int[] switches = new int[7];        ArrayList<IBinder> binders = new ArrayList<IBinder>();        try {            //通过StatusBarManagerService中的registerStatusBar来获取初始设置            mBarService.registerStatusBar(mCommandQueue, iconList, notificationKeys, notifications,                    switches, binders);        } catch (RemoteException ex) {            // If the system process isn't there we're doomed anyway.        }        //对SystemUI上像Clock、ExpandedView、NavigationBar等进行初始化设置        disable(switches[0]);        setSystemUiVisibility(switches[1]);        topAppWindowChanged(switches[2] != 0);        // StatusBarManagerService has a back up of IME token and it's restored here.        setImeWindowStatus(binders.get(0), switches[3], switches[4]);        setHardKeyboardStatus(switches[5] != 0, switches[6] != 0);        // Set up the initial icon state        //icon加载(注：陷阱!!!一不注意就会迷失！！后文详将细分析)        int N = iconList.size();        int viewIndex = 0;        for (int i=0; i<N; i++) {            StatusBarIcon icon = iconList.getIcon(i);            if (icon != null) {                addIcon(iconList.getSlot(i), i, viewIndex, icon);                viewIndex++;            }        }        // Set up the initial notification state        //加载notifications        N = notificationKeys.size();        if (N == notifications.size()) {            for (int i=0; i<N; i++) {                addNotification(notificationKeys.get(i), notifications.get(i));            }        } else {            Log.wtf(TAG, "Notification list length mismatch: keys=" + N                    + " notifications=" + notifications.size());        }        // Put up the view        //获取StatusBar高度        final int height = getStatusBarHeight();        //设置lp各种属性        final WindowManager.LayoutParams lp = new WindowManager.LayoutParams(                ViewGroup.LayoutParams.MATCH_PARENT,                height,                WindowManager.LayoutParams.TYPE_STATUS_BAR,                WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE                    | WindowManager.LayoutParams.FLAG_TOUCHABLE_WHEN_WAKING                    | WindowManager.LayoutParams.FLAG_SPLIT_TOUCH,                // We use a pixel format of RGB565 for the status bar to save memory bandwidth and                // to ensure that the layer can be handled by HWComposer.  On some devices the                // HWComposer is unable to handle SW-rendered RGBX_8888 layers.                PixelFormat.RGB_565);                // the status bar should be in an overlay if possible        final Display defaultDisplay             = ((WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE))                .getDefaultDisplay();        //enable hardware acceleration based on device        //使能硬件加速，不过只有Tablet上才有用        setHardwareAcceleration(lp);        lp.gravity = getStatusBarGravity();        lp.setTitle("StatusBar");        lp.packageName = mContext.getPackageName();        lp.windowAnimations = R.style.Animation_StatusBar;        //在Window上显示StatusBar界面        WindowManagerImpl.getDefault().addView(sb, lp);        mDoNotDisturb = new DoNotDisturb(mContext);    }

       可能大多数朋友都还是云里雾里的，先别急，我们只是把大致流程走完了，细节还没有去分析，接下来我们再来看看StatusBar到底是如何加载Icons的。

       需要分析如何加载Icons，首先我们根据StatusBar.java中的start()方法可以看到，addIcon()方法完成了Icons的加载。那么通过Open Implementation跳转到PhoneStatusBar.java中的addIcon()方法中(因为我们之前传递的Context是PhoneStatusBar的)，代码如下：

public void addIcon(String slot, int index, int viewIndex, StatusBarIcon icon) {        if (SPEW) Slog.d(TAG, "addIcon slot=" + slot + " index=" + index + " viewIndex=" + viewIndex                + " icon=" + icon);        //初始化StatusBarIconView        StatusBarIconView view = new StatusBarIconView(mContext, slot, null);        //加载icon        view.set(icon);        //这里的FEATURE_ANNUCIATOR_NEW_STATUSBAR_STYLE是高通自己定义的，默认为true        if (FeatureQuery.FEATURE_ANNUCIATOR_NEW_STATUSBAR_STYLE) {            //将设置好icon的StatusBarIconView加载到mStatusIcons布局中            mStatusIcons.addView(view, viewIndex, new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, mIconSize));        } else {            mStatusIcons.addView(view, viewIndex, new LinearLayout.LayoutParams(mIconSize, mIconSize));        }    }

        整个加载过程从表面上看来只有3步，但从本质上来讲远远不止3步。首先，我们先来看看addIcon(...)方法所传递的值；我将这里Slog中的内容打印出来，结果如下：

addIcon slot=tty index=6 viewIndex=0 icon=StatusBarIcon(pkg=com.android.systemui id=0x7f02012b level=0 visible=false num=0 )addIcon slot=cdma_eri index=11 viewIndex=1 icon=StatusBarIcon(pkg=com.android.systemui id=0x7f0200d8 level=0 visible=false num=0 )addIcon slot=bluetooth index=4 viewIndex=0 icon=StatusBarIcon(pkg=com.android.systemui id=0x7f020073 level=0 visible=false num=0 )addIcon slot=alarm_clock index=18 viewIndex=3 icon=StatusBarIcon(pkg=com.android.systemui id=0x7f020060 level=0 visible=false num=0 )addIcon slot=sync_active index=2 viewIndex=0 icon=StatusBarIcon(pkg=com.android.systemui id=0x7f020129 level=0 visible=false num=0 )addIcon slot=sync_failing index=1 viewIndex=0 icon=StatusBarIcon(pkg=com.android.systemui id=0x7f02012a level=0 visible=false num=0 )addIcon slot=volume index=9 viewIndex=4 icon=StatusBarIcon(pkg=com.android.systemui id=0x7f0200d6 level=0 visible=false num=0 )addIcon slot=headset index=16 viewIndex=6 icon=StatusBarIcon(pkg=com.android.systemui id=0x7f02000a level=0 visible=false num=0 )

        通过以上log，其中的tty表示语音图标，cdma_eri表示CDMA漫游时显示的图标，其他的大家应该都认识吧，这里就不多讲了。也就是说addIcon()加载的是系统的状态图标。那么我们继续查看它到底是如何加载的，继续查看StatusBarIconView()方法，代码如下：

public StatusBarIconView(Context context, String slot, Notification notification) {        super(context);        //获取资源        final Resources res = context.getResources();        mSlot = slot;        //画笔初始化        mNumberPain = new Paint();        mNumberPain.setTextAlign(Paint.Align.CENTER);        mNumberPain.setColor(res.getColor(R.drawable.notification_number_text_color));        mNumberPain.setAntiAlias(true);        mNotification = notification;        setContentDescription(notification);        // We do not resize and scale system icons (on the right), only notification icons (on the        // left).        if (notification != null) {            final int outerBounds = res.getDimensionPixelSize(R.dimen.status_bar_icon_size);            final int imageBounds = res.getDimensionPixelSize(R.dimen.status_bar_icon_drawing_size);            final float scale = (float)imageBounds / (float)outerBounds;            setScaleX(scale);            setScaleY(scale);            final float alpha = res.getFraction(R.dimen.status_bar_icon_drawing_alpha, 1, 1);            setAlpha(alpha);        }        //按图片原来的size居中显示        setScaleType(ImageView.ScaleType.CENTER);    }

        通过查看StatusBarIconView的继承关系我们可以发现public class StatusBarIconView extends AnimatedImageView ，继续跟踪可以看到public class AnimatedImageView extends ImageView，也就是说我们的StatusBarIconView其实就是一个封装过的ImageView，这样自然能够盛放我们的Icons了。继续查看StatusBarIconView的set()方法，代码如下：

/**     * Returns whether the set succeeded.     */    public boolean set(StatusBarIcon icon) {        final boolean iconEquals = mIcon != null                && streq(mIcon.iconPackage, icon.iconPackage)                && mIcon.iconId == icon.iconId;        final boolean levelEquals = iconEquals                && mIcon.iconLevel == icon.iconLevel;        final boolean visibilityEquals = mIcon != null                && mIcon.visible == icon.visible;        final boolean numberEquals = mIcon != null                && mIcon.number == icon.number;        //将icon的信息copy到mIcon中        mIcon = icon.clone();        setContentDescription(icon.contentDescription);        //获取icon图片并设置到StatusBarIconView中去        if (!iconEquals) {            Drawable drawable = getIcon(icon);            if (drawable == null) {                Slog.w(StatusBar.TAG, "No icon for slot " + mSlot);                return false;            }            setImageDrawable(drawable);        }        //设置需要显示的图片        if (!levelEquals) {            setImageLevel(icon.iconLevel);        }        //这个不太清楚具体是干嘛的        if (!numberEquals) {            if (icon.number > 0 && mContext.getResources().getBoolean(                        R.bool.config_statusBarShowNumber)) {                if (mNumberBackground == null) {                    mNumberBackground = getContext().getResources().getDrawable(                            R.drawable.ic_notification_overlay);                }                placeNumber();            } else {                mNumberBackground = null;                mNumberText = null;            }            invalidate();        }        //设置是否可见        if (!visibilityEquals) {            setVisibility(icon.visible ? VISIBLE : GONE);        }        return true;    }

        到这一步时，我们已经将系统的Icons设置到了mStatusIcons这个mStatusIcons的LinearLayout上了。

        但是，事实真的如此吗？这样就完成icons的初始化了吗？还是那句话，实践是检验真理是否正确的唯一标准！那么我们在PhoneStatusBar.java的addIcon()方法中，加入代码，将程序调用栈打印出来，结果一看便知(当然，也可以用Eclipse的远程调试)！加入代码如下：

StackTraceElement st[]= Thread.currentThread().getStackTrace();        for(int i=0;i<st.length;i++)        System.out.println(i+":"+st[i]);

         重新编译SystemUI，push到/system/app目录下，重新启动，打印部分log如下：

I/System.out(420): 0:dalvik.system.VMStack.getThreadStackTrace(Native Method)I/System.out(420): 1:java.lang.Thread.getStackTrace(Thread.java:591)I/System.out(420): 2:com.android.systemui.statusbar.phone.PhoneStatusBar.addIcon(PhoneStatusBar.java:562)I/System.out(420): 3:com.android.systemui.statusbar.CommandQueue$H.handleMessage(CommandQueue.java:212)I/System.out(420): 4:android.os.Handler.dispatchMessage(Handler.java:99)I/System.out(420): 5:android.os.Looper.loop(Looper.java:137)I/System.out(420): 6:android.app.ActivityThread.main(ActivityThread.java:4450)I/System.out(420): 7:java.lang.reflect.Method.invokeNative(Native Method)I/System.out(420): 8:java.lang.reflect.Method.invoke(Method.java:511)I/System.out(420): 9:com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:787)I/System.out(420): 10:com.android.internal.os.ZygoteInit.main(ZygoteInit.java:554)I/System.out(420): 11:dalvik.system.NativeStart.main(Native Method)... ...

        从打印出来的调用栈，我们可以发现，实际条用addIcon()方法的，并不是我们之前分析的StatusBar，而是来自CommandQueue中的handleMessage，这和我们之前的分析大相径庭啊！也就是说实际上addIcon()在CommandQueue中被调用了，那么我们就反过来分析，直接去CommandQueue.java中的handleMessage找到addIcon()。代码如下：

case OP_SET_ICON: {        StatusBarIcon icon = (StatusBarIcon)msg.obj;        StatusBarIcon old = mList.getIcon(index);        if (old == null) {        mList.setIcon(index, icon);        mCallbacks.addIcon(mList.getSlot(index), index, viewIndex, icon);        } else {           mList.setIcon(index, icon);           mCallbacks.updateIcon(mList.getSlot(index), index, viewIndex,                          old, icon);               }        break;        }

         通过case OP_SET_ICON我们可以继续追查，我们可以查到是谁发送的这个message，代码如下：

public void setIcon(int index, StatusBarIcon icon) {        synchronized (mList) {            int what = MSG_ICON | index;            mHandler.removeMessages(what);            mHandler.obtainMessage(what, OP_SET_ICON, 0, icon.clone()).sendToTarget();        }    }

        在CommandQueue中的setIcon发送了这个消息，通过Open Call Hierarchy继续追查，可以看到如图1：

图 1

         其中第一个onTransact是一个IBinder，后两者是StatusBarManagerService中的方法。通过方法名称，我们可以大致猜测，setIcon是设置Icon，setIconVisibility是这是Icon是否可见，我们从逻辑上分析，如果是开机第一次调用我们应该先设置Icon然后再考虑设置其可见性(看完后文就会明白了:D)。我们直接跳转到StatusBarManagerService中的setIcon()方法，代码如下：

public void setIcon(String slot, String iconPackage, int iconId, int iconLevel,            String contentDescription) {        enforceStatusBar();        synchronized (mIcons) {            int index = mIcons.getSlotIndex(slot);//这里会检查是否是未定义的icon，如果是则抛出异常            if (index < 0) {                throw new SecurityException("invalid status bar icon slot: " + slot);            }            StatusBarIcon icon = new StatusBarIcon(iconPackage, iconId, iconLevel, 0,                    contentDescription);            //Slog.d(TAG, "setIcon slot=" + slot + " index=" + index + " icon=" + icon);            mIcons.setIcon(index, icon);            if (mBar != null) {                try {                    mBar.setIcon(index, icon);//这里调用的                } catch (RemoteException ex) {                }            }        }    }

        继续用Open Call Hierarchy查找哪里调用的setIcon方法，如图2：

图 2

         这里一看就知道应该是StatusBarManager中的setIcon嘛，继续跟踪，代码如下：

public void setIcon(String slot, int iconId, int iconLevel, String contentDescription) {        try {            final IStatusBarService svc = getService();            if (svc != null) {                svc.setIcon(slot, mContext.getPackageName(), iconId, iconLevel,                    contentDescription);//这里调用的            }        } catch (RemoteException ex) {            // system process is dead anyway.            throw new RuntimeException(ex);        }    }

        目前看来还不是很清晰，继续查找，如图3：

图 3

        看到这里请不要头晕，因为真相就在眼前！那么这里应该是谁在调用呢？在本文的一开始，我们就分析了/SourceCode/frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java的start()方法，在该方法中有如下代码：

mIconPolicy = new PhoneStatusBarPolicy(mContext);

        该代码不正是调用了PhoneStatusBarPolicy()构造方法吗？直接跟进去，代码如下：

public PhoneStatusBarPolicy(Context context) {        ... ...        // listen for broadcasts        IntentFilter filter = new IntentFilter();        filter.addAction(Intent.ACTION_ALARM_CHANGED);        filter.addAction(Intent.ACTION_SYNC_STATE_CHANGED);        filter.addAction(AudioManager.RINGER_MODE_CHANGED_ACTION);        filter.addAction(AudioManager.VIBRATE_SETTING_CHANGED_ACTION);        filter.addAction(BluetoothAdapter.ACTION_STATE_CHANGED);    filter.addAction(Intent.ACTION_HEADSET_PLUG); // ted add 2021-4-24        filter.addAction(BluetoothAdapter.ACTION_CONNECTION_STATE_CHANGED);        filter.addAction(TelephonyIntents.ACTION_SIM_STATE_CHANGED);        filter.addAction(TtyIntent.TTY_ENABLED_CHANGE_ACTION);        mContext.registerReceiver(mIntentReceiver, filter, null, mHandler);        ... ...        // TTY status        mService.setIcon("tty",  R.drawable.stat_sys_tty_mode, 0, null);//这里调用        mService.setIconVisibility("tty", false);        // Cdma Roaming Indicator, ERI        mService.setIcon("cdma_eri", R.drawable.stat_sys_roaming_cdma_0, 0, null);//这里调用        mService.setIconVisibility("cdma_eri", false);        ... ...        mService.setIcon("bluetooth", bluetoothIcon, 0, null);//这里调用        mService.setIconVisibility("bluetooth", mBluetoothEnabled);        // Alarm clock        mService.setIcon("alarm_clock", R.drawable.stat_sys_alarm, 0, null);//这里调用        mService.setIconVisibility("alarm_clock", false);        // Sync state        mService.setIcon("sync_active", R.drawable.stat_sys_sync, 0, null);//这里调用        mService.setIcon("sync_failing", R.drawable.stat_sys_sync_error, 0, null);//这里调用        mService.setIconVisibility("sync_active", false);        mService.setIconVisibility("sync_failing", false);        // volume        mService.setIcon("volume", R.drawable.stat_sys_ringer_silent, 0, null);//这里调用        mService.setIconVisibility("volume", false);        updateVolume();      // headset  mService.setIcon("headset", R.drawable.ckt_headset_with_mic, 0, null);//这里调用  mService.setIconVisibility("headset", false);    }

       这里也同时验证了我们前面的猜想，即先设置Icon再设置其可见性。也许你会认为本文到这里已经完结了(太长了，一次看不完...o(╯□╰)o)，但有个别地方我还得再提一下，Android 启动之后，在SystemServer.java的run方法中，调用了StatusBarManagerService的构造方法，代码如下：

... ...            try {                Slog.i(TAG, "Status Bar");                statusBar = new StatusBarManagerService(context, wm);                ServiceManager.addService(Context.STATUS_BAR_SERVICE, statusBar);            } catch (Throwable e) {                reportWtf("starting StatusBarManagerService", e);            }            ... ...

         在StatusBarManagerService的构造方法中，代码如下：

public StatusBarManagerService(Context context, WindowManagerService windowManager) {        mContext = context;        mWindowManager = windowManager;        mWindowManager.setOnHardKeyboardStatusChangeListener(this);        final Resources res = context.getResources();        //这里加载了系统预置的所有icon，路径在：Sourcecode/framework/base/core/res/res/values/config.xml中        mIcons.defineSlots(res.getStringArray(com.android.internal.R.array.config_statusBarIcons));    }

        其中Sourcecode/framework/base/core/res/res/values/config.xml中的预置图标定义如下：

<string-array name="config_statusBarIcons">        <item><xliff:g id="id">ime</xliff:g></item>        <item><xliff:g id="id">sync_failing</xliff:g></item>        <item><xliff:g id="id">sync_active</xliff:g></item>        <item><xliff:g id="id">gps</xliff:g></item>        <item><xliff:g id="id">bluetooth</xliff:g></item>        <item><xliff:g id="id">nfc</xliff:g></item>        <item><xliff:g id="id">tty</xliff:g></item>        <item><xliff:g id="id">speakerphone</xliff:g></item>        <item><xliff:g id="id">mute</xliff:g></item>        <item><xliff:g id="id">volume</xliff:g></item>        <item><xliff:g id="id">wifi</xliff:g></item>        <item><xliff:g id="id">cdma_eri</xliff:g></item>        <item><xliff:g id="id">phone_signal_second_sub</xliff:g></item>        <item><xliff:g id="id">data_connection</xliff:g></item>        <item><xliff:g id="id">phone_evdo_signal</xliff:g></item>        <item><xliff:g id="id">phone_signal</xliff:g></item>        <item><xliff:g id="id">headset</xliff:g></item>        <item><xliff:g id="id">battery</xliff:g></item>        <item><xliff:g id="id">alarm_clock</xliff:g></item>        <item><xliff:g id="id">secure</xliff:g></item>        <item><xliff:g id="id">clock</xliff:g></item></string-array>

        这些东西在后文判断时都会用到，在此记录用以备忘。

       小结

       本文主要是对StatusBar上面的Icons的加载进行了较为细致的分析，后面将继续分析各个部件的加载以及工作流程。其中自己也走了不少弯路，但还是想记录下载，毕竟没有谁从一开始就能做正确吧！将此总结分享出来希望能给各位一些帮助，同时也给自己一些激励，希望自己后面能做的更好。本文主要是枯燥的代码调用与追踪，但对于需要的朋友，我想还是很有帮助的，后面会将相关的时序图以及UML图贴出来，以供参考。