編輯：關於Android編程
本篇只分析SystemUI的加載過程和SystemUI的其中的一個模塊StatusBar的小模塊NavigationBar，以Android6.0代碼進行分析
跟StatusBar相關的服務為SystemUIService,我們查看SystemUIService源碼
public class SystemUIService extends Service {
@Override
public void onCreate() {
super.onCreate();
((SystemUIApplication) getApplication()).startServicesIfNeeded();
//獲取Application調用startServicesIfNeeded
}
@Override
public IBinder onBind(Intent intent) {
return null;
}
/*打印堆棧信息*/
@Override
protected void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
SystemUI[] services = ((SystemUIApplication) getApplication()).getServices();
if (args == null || args.length == 0) {
for (SystemUI ui: services) {
pw.println("dumping service: " + ui.getClass().getName());
ui.dump(fd, pw, args);
}
} else {
String svc = args[0];
for (SystemUI ui: services) {
String name = ui.getClass().getName();
if (name.endsWith(svc)) {
ui.dump(fd, pw, args);
}
}
}
}
}
分析SystemUIService代碼，可以知道SystemUI主要做了兩件事
Application對象加載SystemUI相關的類，這個等下分析SystemUIApplication代碼可以知道 dump打印SystenUISerice運行過程中相關的堆棧信息
那麼SystemUIService又是哪裡開始啟動的呢？竟然SystemUIService是個服務，那麼啟動服務要麼就是startService
要麼就是bindService進行啟動，其啟動方式則需要通過Intent來傳入類名或者包名，因此在源碼中搜索SystemUIService可以對比發現，它在
frameworks\base\services\java\com\android\server\SystemServer.java中進行啟動
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);
}
在SystemServer的run方法中startOtherServices來啟動SystemUIService服務，至於SystemServer則涉及到Android的啟動流程，其大概流程為
int -> ServerManager -> Zygote -> SystemServer
SystemServer中會初始化一些Android的java層的服務，如ActivityManagerService、WindowManagerService等
這裡SystemUI的加載過程就到此告一段落了，下面分析StatusBar的加載流程
上面講到在SystemUIService的onCreate中獲取SystemUIApplication對象來初始化SystemUI相關的類，這些類裡面就包括了StatusBar相關的類，我們查看SystemUIApplication類
@Override
public void onCreate() {
super.onCreate();
// Set the application theme that is inherited by all services. Note that setting the
// application theme in the manifest does only work for activities. Keep this in sync with
// the theme set there.
setTheme(R.style.systemui_theme);
//注釋廣播
IntentFilter filter = new IntentFilter(Intent.ACTION_BOOT_COMPLETED);
filter.setPriority(IntentFilter.SYSTEM_HIGH_PRIORITY);
registerReceiver(new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
//開啟直接返回
if (mBootCompleted) return;
if (DEBUG) Log.v(TAG, "BOOT_COMPLETED received");
unregisterReceiver(this);
//標記啟動
mBootCompleted = true;
//服務是否啟動
if (mServicesStarted) {
final int N = mServices.length;
for (int i = 0; i < N; i++) {
//回調各服務的onBootCompleted函數
mServices[i].onBootCompleted();
}
}
}
}, filter);
}
在SystemUIApplication的onCreate中主要做了
設置主題（這個會影響其SystemUI的界面顯示效果） 注冊開機廣播，設置標志位SystemUIService中的onCreate啟動了這個方法，我們著重分析這個方法
public void startServicesIfNeeded() {
if (mServicesStarted) {
return;
}
if (!mBootCompleted) {
// check to see if maybe it was already completed long before we began
// see ActivityManagerService.finishBooting()
//獲取系統文件中的sys.boot_completed的值
if ("1".equals(SystemProperties.get("sys.boot_completed"))) {
mBootCompleted = true;
if (DEBUG) Log.v(TAG, "BOOT_COMPLETED was already sent");
}
}
Log.v(TAG, "Starting SystemUI services.");
final int N = SERVICES.length;
for (int i=0; i cl = SERVICES[i];
if (DEBUG) Log.d(TAG, "loading: " + cl);
//實例化各個類實例，放入mServices數組中
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 = mComponents;
if (DEBUG) Log.d(TAG, "running: " + mServices[i]);
mServices[i].start();
if (mBootCompleted) {
mServices[i].onBootCompleted();
}
}
//服務啟動標志
mServicesStarted = true;
}
這個方法中，首先判斷mServicesStarted標志為來判斷SystemUI相關的服務是否啟動，同時根據系統配置文件來檢查ActivityManagerService是否finishBooting，然後通過類加載機制來初始化SERVICES數組裡面相關的類加入mServices中，然後start
/**
* The classes of the stuff to start.
*/
private final Class[] SERVICES = new Class[] {
com.android.systemui.tuner.TunerService.class,//定制狀態欄服務
com.android.systemui.keyguard.KeyguardViewMediator.class,//鎖屏相關
com.android.systemui.recents.Recents.class,//近期任務
com.android.systemui.volume.VolumeUI.class,//音量條
com.android.systemui.statusbar.SystemBars.class,//狀態欄
com.android.systemui.usb.StorageNotification.class,//通知欄
com.android.systemui.power.PowerUI.class,//電源相關
com.android.systemui.media.RingtonePlayer.class,//鈴聲播放相關
};
/**
* Hold a reference on the stuff we start.
*/
private final SystemUI[] mServices = new SystemUI[SERVICES.length];
從mServices和SERVICES的定義可以發現SERVICES是一組包含全路徑的相關的類,這些類包含一些我們常見的TunerService（定制狀態欄服務）、
KeyguardViewMediator（鎖屏相關）、Recents(近期任務)、VolumeUI(音量條)、SystemBars(狀態欄)、StorageNotification（通知欄）、PowerUI（電源相關）、RingtonePlayer（鈴聲播放相關）類，它們都是繼承與SystemUI抽象類，現在只分析StatusBar相關的SystemBars類
public class SystemBars extends SystemUI implements ServiceMonitor.Callbacks {
private static final String TAG = "SystemBars";
private static final boolean DEBUG = false;
private static final int WAIT_FOR_BARS_TO_DIE = 500;
// manages the implementation coming from the remote process
private ServiceMonitor mServiceMonitor;
// in-process fallback implementation, per the product config
private BaseStatusBar mStatusBar;
@Override
public void start() {
if (DEBUG) Log.d(TAG, "start");
//實例化ServiceMonitor
mServiceMonitor = new ServiceMonitor(TAG, DEBUG,
mContext, Settings.Secure.BAR_SERVICE_COMPONENT, this);
//start
mServiceMonitor.start(); // will call onNoService if no remote service is found
}
/*服務沒啟動時，ServiceMonitor會回調onNoService*/
@Override
public void onNoService() {
if (DEBUG) Log.d(TAG, "onNoService");
createStatusBarFromConfig(); // fallback to using an in-process implementation
}
/*服務已經啟動的回調*/
@Override
public long onServiceStartAttempt() {
if (DEBUG) Log.d(TAG, "onServiceStartAttempt mStatusBar="+mStatusBar);
if (mStatusBar != null) {
// tear down the in-process version, we'll recreate it again if needed
mStatusBar.destroy();
mStatusBar = null;
return WAIT_FOR_BARS_TO_DIE;
}
return 0;
}
/*系統配置改變*/
@Override
protected void onConfigurationChanged(Configuration newConfig) {
if (mStatusBar != null) {
mStatusBar.onConfigurationChanged(newConfig);
}
}
/*打印堆棧*/
@Override
public void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
if (mStatusBar != null) {
mStatusBar.dump(fd, pw, args);
}
}
/*從xml文件中獲取PhoneStatusBar全路徑，通過類加載器實例化類，調用其start*/
private void createStatusBarFromConfig() {
if (DEBUG) Log.d(TAG, "createStatusBarFromConfig");
final String clsName = mContext.getString(R.string.config_statusBarComponent);
if (clsName == null || clsName.length() == 0) {
throw andLog("No status bar component configured", null);
}
Class cls = null;
try {
cls = mContext.getClassLoader().loadClass(clsName);
} catch (Throwable t) {
throw andLog("Error loading status bar component: " + clsName, t);
}
try {
mStatusBar = (BaseStatusBar) cls.newInstance();
} catch (Throwable t) {
throw andLog("Error creating status bar component: " + clsName, t);
}
mStatusBar.mContext = mContext;
mStatusBar.mComponents = mComponents;
mStatusBar.start();
if (DEBUG) Log.d(TAG, "started " + mStatusBar.getClass().getSimpleName());
}
private RuntimeException andLog(String msg, Throwable t) {
Log.w(TAG, msg, t);
throw new RuntimeException(msg, t);
}
}
我們先從start方法開始分析
@Override
public void start() {
if (DEBUG) Log.d(TAG, "start");
mServiceMonitor = new ServiceMonitor(TAG, DEBUG,
mContext, Settings.Secure.BAR_SERVICE_COMPONENT, this);
mServiceMonitor.start(); // will call onNoService if no remote service is found
}
這裡實例化ServiceMonitor類start，繼續分析ServiceMonitor
...
public ServiceMonitor(String ownerTag, boolean debug,
Context context, String settingKey, Callbacks callbacks) {
mTag = ownerTag + ".ServiceMonitor";
mDebug = debug;
mContext = context;
mSettingKey = settingKey; // Settings.Secure.BAR_SERVICE_COMPONENT
mCallbacks = callbacks;
}
public void start() {
// listen for setting changes
/*Settings.Secure.BAR_SERVICE_COMPONENT改變時回調*/
ContentResolver cr = mContext.getContentResolver();
cr.registerContentObserver(Settings.Secure.getUriFor(mSettingKey),
false /*notifyForDescendents*/, mSettingObserver, UserHandle.USER_ALL);
// listen for package/component changes
//應用安裝，改變，卸載會觸發mBroadcastReceiver廣播
IntentFilter filter = new IntentFilter();
filter.addAction(Intent.ACTION_PACKAGE_ADDED);
filter.addAction(Intent.ACTION_PACKAGE_CHANGED);
filter.addAction(Intent.ACTION_PACKAGE_REMOVED);
filter.addDataScheme("package");
mContext.registerReceiver(mBroadcastReceiver, filter);
mHandler.sendEmptyMessage(MSG_START_SERVICE);
}
...
ServiceMOnitor是一個監聽Settings.Secure.BAR_SERVICE_COMPONENT是否改變的類，在start中通過監聽系統系統時應用的變化來啟動服務
private final BroadcastReceiver mBroadcastReceiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String pkg = intent.getData().getSchemeSpecificPart();
if (mServiceName != null && mServiceName.getPackageName().equals(pkg)) {
mHandler.sendMessage(mHandler.obtainMessage(MSG_PACKAGE_INTENT, intent));
}
}
};
應用裝載時，通過Handler發送MSG_PACKAGE_INTENT消息事件，我們查看Handler消息回調
// internal handler + messages used to serialize access to internal state
public static final int MSG_START_SERVICE = 1; //啟動服務，並非真正啟動，會根據ServiceName進行判斷
public static final int MSG_CONTINUE_START_SERVICE = 2; //啟動服務
public static final int MSG_STOP_SERVICE = 3;//停止服務消息
public static final int MSG_PACKAGE_INTENT = 4;//包安裝事件消息
public static final int MSG_CHECK_BOUND = 5;//包改變或者卸載時，重新啟動服務消息
public static final int MSG_SERVICE_DISCONNECTED = 6;//服務斷開消息
private final Handler mHandler = new Handler() {
public void handleMessage(Message msg) {
switch(msg.what) {
case MSG_START_SERVICE:
startService();
break;
case MSG_CONTINUE_START_SERVICE:
continueStartService();
break;
case MSG_STOP_SERVICE:
stopService();
break;
case MSG_PACKAGE_INTENT:
packageIntent((Intent)msg.obj);
break;
case MSG_CHECK_BOUND:
checkBound();
break;
case MSG_SERVICE_DISCONNECTED:
serviceDisconnected((ComponentName)msg.obj);
break;
}
}
};
private void packageIntent(Intent intent) {
if (mDebug) Log.d(mTag, "packageIntent intent=" + intent
+ " extras=" + bundleToString(intent.getExtras()));
if (Intent.ACTION_PACKAGE_ADDED.equals(intent.getAction())) {
mHandler.sendEmptyMessage(MSG_START_SERVICE);//發送啟動服務消息
} else if (Intent.ACTION_PACKAGE_CHANGED.equals(intent.getAction())
|| Intent.ACTION_PACKAGE_REMOVED.equals(intent.getAction())) {
final PackageManager pm = mContext.getPackageManager();
final boolean serviceEnabled = isPackageAvailable()
&& pm.getApplicationEnabledSetting(mServiceName.getPackageName())
!= PackageManager.COMPONENT_ENABLED_STATE_DISABLED
&& pm.getComponentEnabledSetting(mServiceName)
!= PackageManager.COMPONENT_ENABLED_STATE_DISABLED;
if (mBound && !serviceEnabled) {
stopService();
scheduleCheckBound();
} else if (!mBound && serviceEnabled) {
startService();
}
}
}
當我們SystemUI應用檢測到有新應用裝載時，會發送MSG_START_SERVICE消息來啟動服務，我們接著分析Handler的回調MSG_START_SERVICE消息
private void startService() {
mServiceName = getComponentNameFromSetting();
if (mDebug) Log.d(mTag, "startService mServiceName=" + mServiceName);
if (mServiceName == null) {
mBound = false;
mCallbacks.onNoService();
} else {
long delay = mCallbacks.onServiceStartAttempt();
mHandler.sendEmptyMessageDelayed(MSG_CONTINUE_START_SERVICE, delay);
}
}
/*從ContentProvider數據庫中取得包名*/
private ComponentName getComponentNameFromSetting() {
String cn = Settings.Secure.getStringForUser(mContext.getContentResolver(),
mSettingKey, UserHandle.USER_CURRENT);
return cn == null ? null : ComponentName.unflattenFromString(cn);
}
首先從ContentProvider數據庫中取得包名，如果沒有啟動，則回調CallBaback的onNoService服務，否則發送MSG_CONTINUE_START_SERVICE消息啟動服務
private void continueStartService() {
if (mDebug) Log.d(mTag, "continueStartService");
Intent intent = new Intent().setComponent(mServiceName);
try {
mServiceConnection = new SC();
mBound = mContext.bindService(intent, mServiceConnection, Context.BIND_AUTO_CREATE);
if (mDebug) Log.d(mTag, "mBound: " + mBound);
} catch (Throwable t) {
Log.w(mTag, "Error binding to service: " + mServiceName, t);
}
if (!mBound) {
mCallbacks.onNoService();
}
}
至此可以知道，當遠程服務沒有啟動時，會回調SystemBar的onNoService函數，我們回到SystemBar，分析onNoService函數
...
@Override
public void onNoService() {
if (DEBUG) Log.d(TAG, "onNoService");
createStatusBarFromConfig(); // fallback to using an in-process implementation
}
...
private void createStatusBarFromConfig() {
if (DEBUG) Log.d(TAG, "createStatusBarFromConfig");
final String clsName = mContext.getString(R.string.config_statusBarComponent);//從xml文件讀取類名
if (clsName == null || clsName.length() == 0) {
throw andLog("No status bar component configured", null);
}
//通過類加載器實例化類
Class cls = null;
try {
cls = mContext.getClassLoader().loadClass(clsName);
} catch (Throwable t) {
throw andLog("Error loading status bar component: " + clsName, t);
}
try {
mStatusBar = (BaseStatusBar) cls.newInstance();
} catch (Throwable t) {
throw andLog("Error creating status bar component: " + clsName, t);
}
mStatusBar.mContext = mContext;
mStatusBar.mComponents = mComponents;
mStatusBar.start();//調用類的start方法
if (DEBUG) Log.d(TAG, "started " + mStatusBar.getClass().getSimpleName());
}
上面分析可以得知，當遠程服務沒有啟動時，首先從xml文件讀取要啟動的類名，我們來查看這個xml文件
res\values\config.xml
com.android.systemui.statusbar.phone.PhoneStatusBar
從上面可以知道，最終程序會加載PhoneStatusBar這個類，接下來分析PhoneStatusBar
首先我們從上面分析得知，當實例化PhoneStatusBar類後會調用start方法，我們就從PhoneStatusBar的start方法開始分析
...
@Override
public void start() {
//獲取WindowManager，初始化當前顯示界面大小
mDisplay = ((WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE))
.getDefaultDisplay();
updateDisplaySize();
//src繪圖模式
mScrimSrcModeEnabled = mContext.getResources().getBoolean(
R.bool.config_status_bar_scrim_behind_use_src);
//調用父類start方法
super.start(); // calls createAndAddWindows()
//MediaSession相關
mMediaSessionManager
= (MediaSessionManager) mContext.getSystemService(Context.MEDIA_SESSION_SERVICE);
// TODO: use MediaSessionManager.SessionListener to hook us up to future updates
// in session state
//添加導航欄
addNavigationBar();
// Lastly, call to the icon policy to install/update all the icons.
//更新狀態欄圖標
mIconPolicy = new PhoneStatusBarPolicy(mContext, mCastController, mHotspotController,
mUserInfoController, mBluetoothController);
mIconPolicy.setCurrentUserSetup(mUserSetup);
mSettingsObserver.onChange(false); // set up
mHeadsUpObserver.onChange(true); // set up
if (ENABLE_HEADS_UP) {
mContext.getContentResolver().registerContentObserver(
Settings.Global.getUriFor(Settings.Global.HEADS_UP_NOTIFICATIONS_ENABLED), true,
mHeadsUpObserver);
mContext.getContentResolver().registerContentObserver(
Settings.Global.getUriFor(SETTING_HEADS_UP_TICKER), true,
mHeadsUpObserver);
}
mUnlockMethodCache = UnlockMethodCache.getInstance(mContext);
mUnlockMethodCache.addListener(this);
//鎖屏
startKeyguard();
mDozeServiceHost = new DozeServiceHost();
KeyguardUpdateMonitor.getInstance(mContext).registerCallback(mDozeServiceHost);
putComponent(DozeHost.class, mDozeServiceHost);
putComponent(PhoneStatusBar.class, this);
/// M:add for multi window @{
if(MultiWindowProxy.isSupported()) {
registerMWProxyAgain();
}
/// @}
setControllerUsers();
notifyUserAboutHiddenNotifications();
mScreenPinningRequest = new ScreenPinningRequest(mContext);
}
...
我們接著分析PhoneStatusBar父類的BaseStatusBar的start方法
...
public void start() {
//獲取Dispaly
mWindowManager = (WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE);
mWindowManagerService = WindowManagerGlobal.getWindowManagerService();
mDisplay = mWindowManager.getDefaultDisplay();
mDevicePolicyManager = (DevicePolicyManager)mContext.getSystemService(
Context.DEVICE_POLICY_SERVICE);
mNotificationColorUtil = NotificationColorUtil.getInstance(mContext);
mNotificationData = new NotificationData(this);
mAccessibilityManager = (AccessibilityManager)
mContext.getSystemService(Context.ACCESSIBILITY_SERVICE);
mDreamManager = IDreamManager.Stub.asInterface(
ServiceManager.checkService(DreamService.DREAM_SERVICE));
mPowerManager = (PowerManager) mContext.getSystemService(Context.POWER_SERVICE);
//監聽設置文件的改變，以便更新ContenProvider數據庫
mContext.getContentResolver().registerContentObserver(
Settings.Global.getUriFor(Settings.Global.DEVICE_PROVISIONED), true,
mSettingsObserver);
mContext.getContentResolver().registerContentObserver(
Settings.Global.getUriFor(Settings.Global.ZEN_MODE), false,
mSettingsObserver);
mContext.getContentResolver().registerContentObserver(
Settings.Secure.getUriFor(Settings.Secure.LOCK_SCREEN_SHOW_NOTIFICATIONS), false,
mSettingsObserver,
UserHandle.USER_ALL);
mContext.getContentResolver().registerContentObserver(
Settings.Secure.getUriFor(Settings.Secure.LOCK_SCREEN_ALLOW_PRIVATE_NOTIFICATIONS),
true,
mLockscreenSettingsObserver,
UserHandle.USER_ALL);
//加載startbarService服務
mBarService = IStatusBarService.Stub.asInterface(
ServiceManager.getService(Context.STATUS_BAR_SERVICE));
//設置近期任務回調
mRecents = getComponent(Recents.class);
mRecents.setCallback(this);
//獲取本地配置
final Configuration currentConfig = mContext.getResources().getConfiguration();
mLocale = currentConfig.locale;
mLayoutDirection = TextUtils.getLayoutDirectionFromLocale(mLocale);
mFontScale = currentConfig.fontScale;
mUserManager = (UserManager) mContext.getSystemService(Context.USER_SERVICE);
//加載動畫
mLinearOutSlowIn = AnimationUtils.loadInterpolator(mContext,
android.R.interpolator.linear_out_slow_in);
mFastOutLinearIn = AnimationUtils.loadInterpolator(mContext,
android.R.interpolator.fast_out_linear_in);
// Connect in to the status bar manager service
StatusBarIconList iconList = new StatusBarIconList();
mCommandQueue = new CommandQueue(this, iconList);
int[] switches = new int[8];
ArrayList binders = new ArrayList();
try {
mBarService.registerStatusBar(mCommandQueue, iconList, switches, binders);
} catch (RemoteException ex) {
// If the system process isn't there we're doomed anyway.
}
//調用createAndAddWindows方法
createAndAddWindows();
mSettingsObserver.onChange(false); // set up
disable(switches[0], switches[6], false /* animate */);
setSystemUiVisibility(switches[1], 0xffffffff);
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], switches[5] != 0);
// Set up the initial icon state
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.="" try="" mnotificationlistener.registerassystemservice(mcontext,="" new="" componentname(mcontext.getpackagename(),="" getclass().getcanonicalname()),="" userhandle.user_all);="" catch="" (remoteexception="" e)="" log.e(tag,="" "unable="" to="" register="" listener",="" e);="" (debug)="" log.d(tag,="" string.format(="" "init:="" icons="%d" disabled="0x%08x" lights="0x%08x" menu="0x%08x" imebutton="0x%08x"," iconlist.size(),="" switches[0],="" switches[1],="" switches[2],="" switches[3]="" ));="" mcurrentuserid="ActivityManager.getCurrentUser();" setheadsupuser(mcurrentuserid);="" intentfilter="" filter="new" intentfilter();="" filter.addaction(intent.action_user_switched);="" filter.addaction(intent.action_user_added);="" filter.addaction(intent.action_user_present);="" filter.addaction(banner_action_cancel);="" filter.addaction(banner_action_setup);="" mcontext.registerreceiver(mbroadcastreceiver,="" filter);="" allusersfilter="new" allusersfilter.addaction(="" devicepolicymanager.action_device_policy_manager_state_changed);="" mcontext.registerreceiverasuser(mallusersreceiver,="" userhandle.all,="" allusersfilter,="" null,="" null);="" updatecurrentprofilescache();="" ...
BaseStatusBar關於StatusBar相關的最主要是調用了createAndAddWindows方法，我們看下這個方法的定義
/**
* Create all windows necessary for the status bar (including navigation, overlay panels, etc)
* and add them to the window manager.
*/
protected abstract void createAndAddWindows();
這是一個抽象方法，也就是說，它會回調到子類的createAndAddWindows的實現方法中，我們重新回到PhoneStatusBar中，找到createAndAddWindows的方法實現
createAndAddWindows
...
@Override
public void createAndAddWindows() {
addStatusBarWindow();
}
private void addStatusBarWindow() {
makeStatusBarView();//創建statusbar視圖
mStatusBarWindowManager = new StatusBarWindowManager(mContext);
//通過StatusBarWindowManager類的add方法加載到Window窗體中
mStatusBarWindowManager.add(mStatusBarWindow, getStatusBarHeight());
}
...
protected PhoneStatusBarView makeStatusBarView() {
final Context context = mContext;
//通過Resources更新顯示大小和一些資源文件
Resources res = context.getResources();
updateDisplaySize(); // populates mDisplayMetrics
updateResources();
//加載StartBarWindowView視圖
mStatusBarWindow = (StatusBarWindowView) View.inflate(context,
R.layout.super_status_bar, null);
mStatusBarWindow.setService(this);
//監聽下拉事件
mStatusBarWindow.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
checkUserAutohide(v, event);
if (event.getAction() == MotionEvent.ACTION_DOWN) {
if (mExpandedVisible) {
animateCollapsePanels();
}
}
return mStatusBarWindow.onTouchEvent(event);
}
});
//狀態欄
mStatusBarView = (PhoneStatusBarView) mStatusBarWindow.findViewById(R.id.status_bar);
mStatusBarView.setBar(this);
//
PanelHolder holder = (PanelHolder) mStatusBarWindow.findViewById(R.id.panel_holder);
mStatusBarView.setPanelHolder(holder);
//通知欄
mNotificationPanel = (NotificationPanelView) mStatusBarWindow.findViewById(
R.id.notification_panel);
mNotificationPanel.setStatusBar(this);
// M: setBackground in 512 low ram device
if (!ActivityManager.isHighEndGfx() && !FeatureOptions.LOW_RAM_SUPPORT) {
mStatusBarWindow.setBackground(null);
mNotificationPanel.setBackground(new FastColorDrawable(context.getColor(
R.color.notification_panel_solid_background)));
}
//狀態欄通知
mHeadsUpManager = new HeadsUpManager(context, mStatusBarWindow);
mHeadsUpManager.setBar(this);
mHeadsUpManager.addListener(this);
mHeadsUpManager.addListener(mNotificationPanel);
mNotificationPanel.setHeadsUpManager(mHeadsUpManager);
mNotificationData.setHeadsUpManager(mHeadsUpManager);
if (MULTIUSER_DEBUG) {
mNotificationPanelDebugText = (TextView) mNotificationPanel.findViewById(
R.id.header_debug_info);
mNotificationPanelDebugText.setVisibility(View.VISIBLE);
}
try {
//是否顯示導航欄
boolean showNav = mWindowManagerService.hasNavigationBar();
Log.v(TAG, "hasNavigationBar=" + showNav);
if (showNav) {
/// M: add for multi window @{
//加載導航欄布局
int layoutId = R.layout.navigation_bar;
if(MultiWindowProxy.isSupported()) {
layoutId = R.layout.navigation_bar_float_window;
}
mNavigationBarView = (NavigationBarView) View.inflate(context,
/*R.layout.navigation_bar*/layoutId, null);
/// @}
mNavigationBarView.setDisabledFlags(mDisabled1);
mNavigationBarView.setBar(this);
mNavigationBarView.setOnVerticalChangedListener(
new NavigationBarView.OnVerticalChangedListener() {
@Override
public void onVerticalChanged(boolean isVertical) {
if (mAssistManager != null) {
mAssistManager.onConfigurationChanged();
}
mNotificationPanel.setQsScrimEnabled(!isVertical);
}
});
//設置導航欄觸摸事件
mNavigationBarView.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
checkUserAutohide(v, event);
return false;
}});
}
} catch (RemoteException ex) {
// no window manager? good luck with that
}
mAssistManager = new AssistManager(this, context);
// figure out which pixel-format to use for the status bar.
mPixelFormat = PixelFormat.OPAQUE;
//下拉通知欄
mStackScroller = (NotificationStackScrollLayout) mStatusBarWindow.findViewById(
R.id.notification_stack_scroller);
mStackScroller.setLongPressListener(getNotificationLongClicker());
mStackScroller.setPhoneStatusBar(this);
mStackScroller.setGroupManager(mGroupManager);
mStackScroller.setHeadsUpManager(mHeadsUpManager);
mGroupManager.setOnGroupChangeListener(mStackScroller);
mKeyguardIconOverflowContainer =
(NotificationOverflowContainer) LayoutInflater.from(mContext).inflate(
R.layout.status_bar_notification_keyguard_overflow, mStackScroller, false);
mKeyguardIconOverflowContainer.setOnActivatedListener(this);
mKeyguardIconOverflowContainer.setOnClickListener(mOverflowClickListener);
mStackScroller.setOverflowContainer(mKeyguardIconOverflowContainer);
SpeedBumpView speedBump = (SpeedBumpView) LayoutInflater.from(mContext).inflate(
R.layout.status_bar_notification_speed_bump, mStackScroller, false);
mStackScroller.setSpeedBumpView(speedBump);
mEmptyShadeView = (EmptyShadeView) LayoutInflater.from(mContext).inflate(
R.layout.status_bar_no_notifications, mStackScroller, false);
mStackScroller.setEmptyShadeView(mEmptyShadeView);
//下拉清除鍵
mDismissView = (DismissView) LayoutInflater.from(mContext).inflate(
R.layout.status_bar_notification_dismiss_all, mStackScroller, false);
mDismissView.setOnButtonClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
MetricsLogger.action(mContext, MetricsLogger.ACTION_DISMISS_ALL_NOTES);
clearAllNotifications();
}
});
mStackScroller.setDismissView(mDismissView);
mExpandedContents = mStackScroller;
mBackdrop = (BackDropView) mStatusBarWindow.findViewById(R.id.backdrop);
mBackdropFront = (ImageView) mBackdrop.findViewById(R.id.backdrop_front);
mBackdropBack = (ImageView) mBackdrop.findViewById(R.id.backdrop_back);
ScrimView scrimBehind = (ScrimView) mStatusBarWindow.findViewById(R.id.scrim_behind);
ScrimView scrimInFront = (ScrimView) mStatusBarWindow.findViewById(R.id.scrim_in_front);
View headsUpScrim = mStatusBarWindow.findViewById(R.id.heads_up_scrim);
mScrimController = new ScrimController(scrimBehind, scrimInFront, headsUpScrim,
mScrimSrcModeEnabled);
mHeadsUpManager.addListener(mScrimController);
mStackScroller.setScrimController(mScrimController);
mScrimController.setBackDropView(mBackdrop);
mStatusBarView.setScrimController(mScrimController);
mDozeScrimController = new DozeScrimController(mScrimController, context);
mHeader = (StatusBarHeaderView) mStatusBarWindow.findViewById(R.id.header);
mHeader.setActivityStarter(this);
//鎖屏相關
mKeyguardStatusBar = (KeyguardStatusBarView) mStatusBarWindow.findViewById(R.id.keyguard_header);
mKeyguardStatusView = mStatusBarWindow.findViewById(R.id.keyguard_status_view);
mKeyguardBottomArea =
(KeyguardBottomAreaView) mStatusBarWindow.findViewById(R.id.keyguard_bottom_area);
mKeyguardBottomArea.setActivityStarter(this);
mKeyguardBottomArea.setAssistManager(mAssistManager);
mKeyguardIndicationController = new KeyguardIndicationController(mContext,
(KeyguardIndicationTextView) mStatusBarWindow.findViewById(
R.id.keyguard_indication_text),
mKeyguardBottomArea.getLockIcon());
mKeyguardBottomArea.setKeyguardIndicationController(mKeyguardIndicationController);
// set the inital view visibility
setAreThereNotifications();
//主要是控制一些系統圖標，第三方圖標等的顯示和更新
mIconController = new StatusBarIconController(
mContext, mStatusBarView, mKeyguardStatusBar, this);
// Background thread for any controllers that need it.
mHandlerThread = new HandlerThread(TAG, Process.THREAD_PRIORITY_BACKGROUND);
mHandlerThread.start();
// Other icons
//位置控制
mLocationController = new LocationControllerImpl(mContext,
mHandlerThread.getLooper()); // will post a notification
//電池
mBatteryController = new BatteryController(mContext);
mBatteryController.addStateChangedCallback(new BatteryStateChangeCallback() {
@Override
public void onPowerSaveChanged() {
mHandler.post(mCheckBarModes);
if (mDozeServiceHost != null) {
mDozeServiceHost.firePowerSaveChanged(mBatteryController.isPowerSave());
}
}
@Override
public void onBatteryLevelChanged(int level, boolean pluggedIn, boolean charging) {
// noop
}
});
//網絡
mNetworkController = new NetworkControllerImpl(mContext, mHandlerThread.getLooper());
//熱點
mHotspotController = new HotspotControllerImpl(mContext);
//藍牙
mBluetoothController = new BluetoothControllerImpl(mContext, mHandlerThread.getLooper());
mSecurityController = new SecurityControllerImpl(mContext);
/// M: add extra tiles @{
// add HotKnot in quicksetting
if (SIMHelper.isMtkHotKnotSupport()) {
Log.d(TAG, "makeStatusBarView : HotKnotControllerImpl");
mHotKnotController = new HotKnotControllerImpl(mContext);
} else {
mHotKnotController = null;
}
// add AudioProfile in quicksetting
if (SIMHelper.isMtkAudioProfilesSupport()) {
Log.d(TAG, "makeStatusBarView : AudioProfileControllerImpl");
mAudioProfileController = new AudioProfileControllerImpl(mContext);
} else {
mAudioProfileController = null;
}
SIMHelper.setContext(mContext);
// /@}
if (mContext.getResources().getBoolean(R.bool.config_showRotationLock)) {
mRotationLockController = new RotationLockControllerImpl(mContext);
}
mUserInfoController = new UserInfoController(mContext);
mVolumeComponent = getComponent(VolumeComponent.class);
if (mVolumeComponent != null) {
mZenModeController = mVolumeComponent.getZenController();
}
Log.d(TAG, "makeStatusBarView : CastControllerImpl +");
mCastController = new CastControllerImpl(mContext);
Log.d(TAG, "makeStatusBarView : CastControllerImpl -");
final SignalClusterView signalCluster =
(SignalClusterView) mStatusBarView.findViewById(R.id.signal_cluster);
final SignalClusterView signalClusterKeyguard =
(SignalClusterView) mKeyguardStatusBar.findViewById(R.id.signal_cluster);
final SignalClusterView signalClusterQs =
(SignalClusterView) mHeader.findViewById(R.id.signal_cluster);
mNetworkController.addSignalCallback(signalCluster);
mNetworkController.addSignalCallback(signalClusterKeyguard);
mNetworkController.addSignalCallback(signalClusterQs);
signalCluster.setSecurityController(mSecurityController);
signalCluster.setNetworkController(mNetworkController);
signalClusterKeyguard.setSecurityController(mSecurityController);
signalClusterKeyguard.setNetworkController(mNetworkController);
signalClusterQs.setSecurityController(mSecurityController);
signalClusterQs.setNetworkController(mNetworkController);
final boolean isAPhone = mNetworkController.hasVoiceCallingFeature();
if (isAPhone) {
mNetworkController.addEmergencyListener(mHeader);
}
/// M: Support "Operator plugin - Customize Carrier Label for PLMN" @{
mStatusBarPlmnPlugin = PluginFactory.getStatusBarPlmnPlugin(context);
if (supportCustomizeCarrierLabel()) {
mCustomizeCarrierLabel = mStatusBarPlmnPlugin.customizeCarrierLabel(
mNotificationPanel, null);
}
/// M: Support "Operator plugin - Customize Carrier Label for PLMN" @}
//手電筒
mFlashlightController = new FlashlightController(mContext);
//鍵盤
mKeyguardBottomArea.setFlashlightController(mFlashlightController);
mKeyguardBottomArea.setPhoneStatusBar(this);
mKeyguardBottomArea.setUserSetupComplete(mUserSetup);
mAccessibilityController = new AccessibilityController(mContext);
mKeyguardBottomArea.setAccessibilityController(mAccessibilityController);
mNextAlarmController = new NextAlarmController(mContext);
mKeyguardMonitor = new KeyguardMonitor(mContext);
if (UserSwitcherController.isUserSwitcherAvailable(UserManager.get(mContext))) {
mUserSwitcherController = new UserSwitcherController(mContext, mKeyguardMonitor,
mHandler);
}
mKeyguardUserSwitcher = new KeyguardUserSwitcher(mContext,
(ViewStub) mStatusBarWindow.findViewById(R.id.keyguard_user_switcher),
mKeyguardStatusBar, mNotificationPanel, mUserSwitcherController);
// Set up the quick settings tile panel
mQSPanel = (QSPanel) mStatusBarWindow.findViewById(R.id.quick_settings_panel);
if (mQSPanel != null) {
final QSTileHost qsh = new QSTileHost(mContext, this,
mBluetoothController, mLocationController, mRotationLockController,
mNetworkController, mZenModeController, mHotspotController,
mCastController, mFlashlightController,
mUserSwitcherController, mKeyguardMonitor,
mSecurityController,
/// M: add HotKnot in quicksetting
mHotKnotController,
/// M: add AudioProfile in quicksetting
mAudioProfileController
);
mQSPanel.setHost(qsh);
mQSPanel.setTiles(qsh.getTiles());
mBrightnessMirrorController = new BrightnessMirrorController(mStatusBarWindow);
mQSPanel.setBrightnessMirror(mBrightnessMirrorController);
mHeader.setQSPanel(mQSPanel);
qsh.setCallback(new QSTileHost.Callback() {
@Override
public void onTilesChanged() {
mQSPanel.setTiles(qsh.getTiles());
}
});
}
// User info. Trigger first load.
mHeader.setUserInfoController(mUserInfoController);
mKeyguardStatusBar.setUserInfoController(mUserInfoController);
mKeyguardStatusBar.setUserSwitcherController(mUserSwitcherController);
mUserInfoController.reloadUserInfo();
mHeader.setBatteryController(mBatteryController);
((BatteryMeterView) mStatusBarView.findViewById(R.id.battery)).setBatteryController(
mBatteryController);
mKeyguardStatusBar.setBatteryController(mBatteryController);
mHeader.setNextAlarmController(mNextAlarmController);
PowerManager pm = (PowerManager) mContext.getSystemService(Context.POWER_SERVICE);
mBroadcastReceiver.onReceive(mContext,
new Intent(pm.isScreenOn() ? Intent.ACTION_SCREEN_ON : Intent.ACTION_SCREEN_OFF));
// receive broadcasts
//注冊系統廣播
IntentFilter filter = new IntentFilter();
filter.addAction(Intent.ACTION_CLOSE_SYSTEM_DIALOGS);
filter.addAction(Intent.ACTION_SCREEN_OFF);
filter.addAction(Intent.ACTION_SCREEN_ON);
context.registerReceiverAsUser(mBroadcastReceiver, UserHandle.ALL, filter, null, null);
IntentFilter demoFilter = new IntentFilter();
if (DEBUG_MEDIA_FAKE_ARTWORK) {
demoFilter.addAction(ACTION_FAKE_ARTWORK);
}
demoFilter.addAction(ACTION_DEMO);
context.registerReceiverAsUser(mDemoReceiver, UserHandle.ALL, demoFilter,
android.Manifest.permission.DUMP, null);
// listen for USER_SETUP_COMPLETE setting (per-user)
resetUserSetupObserver();
// disable profiling bars, since they overlap and clutter the output on app windows
ThreadedRenderer.overrideProperty("disableProfileBars", "true");
// Private API call to make the shadows look better for Recents
ThreadedRenderer.overrideProperty("ambientRatio", String.valueOf(1.5f));
mStatusBarPlmnPlugin.addPlmn((LinearLayout)mStatusBarView.
findViewById(R.id.status_bar_contents), mContext);
return mStatusBarView;
}
...
因為這塊涉及的太廣，所以接下來只分析StatusBar相關的一塊，以導航欄為例進行講解，我們重新回到PhoneStatusBar的start方法中，找到導航欄這塊，發現它是調用addNavigationBar函數，所以我們查看這個函數：
...
// For small-screen devices (read: phones) that lack hardware navigation buttons
private void addNavigationBar() {
if (DEBUG) Log.v(TAG, "addNavigationBar: about to add " + mNavigationBarView);
//1.判斷mNavigationBarView是否為空，這個視圖有上面分析的makeStatusBarView方法中進行創建
if (mNavigationBarView == null) return;
//2.加載導航欄的具體顯示（導航欄的顯示由橫向顯示和豎向顯示，後面分析）
prepareNavigationBarView();
//3.根據LayoutParams，加載導航欄到窗體中
mWindowManager.addView(mNavigationBarView, getNavigationBarLayoutParams());
}
...
private void prepareNavigationBarView() {
mNavigationBarView.reorient();
//設置導航欄三個圖標的點擊事件
mNavigationBarView.getRecentsButton().setOnClickListener(mRecentsClickListener);
mNavigationBarView.getRecentsButton().setOnTouchListener(mRecentsPreloadOnTouchListener);
mNavigationBarView.getRecentsButton().setLongClickable(true);
mNavigationBarView.getRecentsButton().setOnLongClickListener(mLongPressBackRecentsListener);
mNavigationBarView.getBackButton().setLongClickable(true);
mNavigationBarView.getBackButton().setOnLongClickListener(mLongPressBackRecentsListener);
mNavigationBarView.getHomeButton().setOnTouchListener(mHomeActionListener);
mNavigationBarView.getHomeButton().setOnLongClickListener(mLongPressHomeListener);
mAssistManager.onConfigurationChanged();
/// M: add for multi window @{
if(MultiWindowProxy.isSupported()){
mNavigationBarView.getFloatButton().setOnClickListener(mFloatClickListener);
if(mIsSplitModeEnable){
mNavigationBarView.getFloatModeButton().setOnClickListener(mFloatModeClickListener);
mNavigationBarView.getSplitModeButton().setOnClickListener(mSplitModeClickListener);
}
MultiWindowProxy.getInstance().setSystemUiCallback(new MWSystemUiCallback());
}
/// @}
}
我們根據上面的注釋來進行分析，主要內容有
1. 導航欄布局的創建
2. 導航欄布局分析及加載
3. 導航欄LayoutParams分析
導航欄布局的創建在PhoneStatusBar的makeStatusBarView方法中，我們可以看到導航欄是怎麼創建的
...
protected PhoneStatusBarView makeStatusBarView() {
...
...
try {
//是否顯示導航欄
boolean showNav = mWindowManagerService.hasNavigationBar();
Log.v(TAG, "hasNavigationBar=" + showNav);
if (showNav) {
/// M: add for multi window @{
//加載導航欄布局
int layoutId = R.layout.navigation_bar;
//是否支持多窗口
if(MultiWindowProxy.isSupported()) {
layoutId = R.layout.navigation_bar_float_window;
}
mNavigationBarView = (NavigationBarView) View.inflate(context,
/*R.layout.navigation_bar*/layoutId, null);
/// @}
mNavigationBarView.setDisabledFlags(mDisabled1);
mNavigationBarView.setBar(this);
mNavigationBarView.setOnVerticalChangedListener(
new NavigationBarView.OnVerticalChangedListener() {
@Override
public void onVerticalChanged(boolean isVertical) {
if (mAssistManager != null) {
mAssistManager.onConfigurationChanged();
}
mNotificationPanel.setQsScrimEnabled(!isVertical);
}
});
//設置導航欄觸摸事件
mNavigationBarView.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
checkUserAutohide(v, event);
return false;
}});
}
} catch (RemoteException ex) {
// no window manager? good luck with that
}
...
...
}
...
首先由mWindowManagerService的hasNavigationBar來決定是否顯示導航欄，同時通過加載navigation_bar（多窗口加載navigation_bar_float_window）布局來顯示導航欄，我們來查看hasNavigationBar方法，因為mWidnwoManagerService是IWindowManagerService由PhoneWindowManager進行調用：
frameworks\base\service\core\java\com\android\server\PhoneWindowManager.java
PhoneWindowManager
...
// Use this instead of checking config_showNavigationBar so that it can be consistently
// overridden by qemu.hw.mainkeys in the emulator.
@Override
public boolean hasNavigationBar() {
return mHasNavigationBar;
}
...
mHasNavigationBar = res.getBoolean(com.android.internal.R.bool.config_showNavigationBar);
// Allow a system property to override this. Used by the emulator.
// See also hasNavigationBar().
String navBarOverride = SystemProperties.get("qemu.hw.mainkeys");
if ("1".equals(navBarOverride)) {
mHasNavigationBar = false;
} else if ("0".equals(navBarOverride)) {
mHasNavigationBar = true;
}
...
從framework\base\core\res\res\valuse\config.xml中獲取mHashNavigationBar的值
ture
然後從系統配置位置中取qemu.hw.mainkeys的值，所以這裡給我們提供了一個隱藏狀態欄的新思路，除了在createAndAddWindows中注釋掉addNavigationBar函數外，我們也可以通過修改framework下的config.xml的config_showNavigationBar的值和修改系統配置文件的值來達到隱藏狀態欄的目的
導航欄布局分析及加載
...
private void prepareNavigationBarView() {
mNavigationBarView.reorient();
//設置導航欄三個圖標的點擊事件
mNavigationBarView.getRecentsButton().setOnClickListener(mRecentsClickListener);
mNavigationBarView.getRecentsButton().setOnTouchListener(mRecentsPreloadOnTouchListener);
mNavigationBarView.getRecentsButton().setLongClickable(true);
mNavigationBarView.getRecentsButton().setOnLongClickListener(mLongPressBackRecentsListener);
mNavigationBarView.getBackButton().setLongClickable(true);
mNavigationBarView.getBackButton().setOnLongClickListener(mLongPressBackRecentsListener);
mNavigationBarView.getHomeButton().setOnTouchListener(mHomeActionListener);
mNavigationBarView.getHomeButton().setOnLongClickListener(mLongPressHomeListener);
mAssistManager.onConfigurationChanged();
/// M: add for multi window @{
if(MultiWindowProxy.isSupported()){
mNavigationBarView.getFloatButton().setOnClickListener(mFloatClickListener);
if(mIsSplitModeEnable){
mNavigationBarView.getFloatModeButton().setOnClickListener(mFloatModeClickListener);
mNavigationBarView.getSplitModeButton().setOnClickListener(mSplitModeClickListener);
}
MultiWindowProxy.getInstance().setSystemUiCallback(new MWSystemUiCallback());
}
/// @}
}
...
導航欄布局的確切顯示在prepareNavigationBarView中的mNavigationBarView.reorient();來決定，我們查看reorient方法
reorient
...
public void reorient() {
//獲取屏幕方向
final int rot = mDisplay.getRotation();
//隱藏導航欄布局
for (int i=0; i<4; i++) {
mRotatedViews[i].setVisibility(View.GONE);
}
//根據屏幕方向顯示導航欄布局
mCurrentView = mRotatedViews[rot];
mCurrentView.setVisibility(View.VISIBLE);
setLayoutTransitionsEnabled(mLayoutTransitionsEnabled);
getImeSwitchButton().setOnClickListener(mImeSwitcherClickListener);
mDeadZone = (DeadZone) mCurrentView.findViewById(R.id.deadzone);
// force the low profile & disabled states into compliance
mBarTransitions.init();
setDisabledFlags(mDisabledFlags, true /* force */);
setMenuVisibility(mShowMenu, true /* force */);
if (DEBUG) {
Log.d(TAG, "reorient(): rot=" + mDisplay.getRotation());
}
updateTaskSwitchHelper();
setNavigationIconHints(mNavigationIconHints, true);
}
...
導航欄的顯示由屏幕的方向來決定，而導航欄有兩種不同的顯示方式，橫向顯示和豎向顯示，我們可以從mRotatedViews進行追查到
...
View[] mRotatedViews = new View[4];
...
@Override
public void onFinishInflate() {
//屏幕方位0和180方向顯示的導航欄為rot0
mRotatedViews[Surface.ROTATION_0] =
mRotatedViews[Surface.ROTATION_180] = findViewById(R.id.rot0);
//屏幕訪問90和270顯示的導航欄為rot90
mRotatedViews[Surface.ROTATION_90] = findViewById(R.id.rot90);
mRotatedViews[Surface.ROTATION_270] = mRotatedViews[Surface.ROTATION_90];
//mCurrentView = mRotatedViews[Surface.ROTATION_0];
mCurrentView = mRotatedViews[Surface.ROTATION_90];
getImeSwitchButton().setOnClickListener(mImeSwitcherClickListener);
updateRTLOrder();
}
...
布局加載完成後，會回調onFinishInflate方法，在這方法中對屏幕的幾個方向初始化4個導航欄view，其中0和180為橫向布局，90和270為縱向布局，我們可以從導航欄（NavigationBarView）布局文件中可以看出
res\layout\navigation_bar.xml和res\layout\navigation_bar
<framelayout android:id="@+id/rot0" android:layout_height="match_parent" android:layout_width="match_parent">
<framelayout android:layout_height="match_parent" android:layout_weight="0" android:layout_width="@dimen/navigation_side_padding">
</framelayout>
</framelayout>
<framelayout android:id="@+id/rot90" android:layout_height="match_parent" android:layout_width="match_parent" android:paddingtop="0dp" android:visibility="gone">
<framelayout android:layout_height="@dimen/navigation_side_padding" android:layout_weight="0" android:layout_width="match_parent">
</framelayout>
</framelayout>
所以說，當我們的需求為0或者90度方向，要想導航欄縱向顯示，我們只需要修改成導航欄縱向布局即可，當然我們也可以按需求來隱藏某些導航欄按鍵（布局中設置某些控件為gone）
@Override
public void onFinishInflate() {
mRotatedViews[Surface.ROTATION_0] =
mRotatedViews[Surface.ROTATION_180] = findViewById(R.id.rot0);
mRotatedViews[Surface.ROTATION_90] = findViewById(R.id.rot90);
mRotatedViews[Surface.ROTATION_270] = mRotatedViews[Surface.ROTATION_90];
//mCurrentView = mRotatedViews[Surface.ROTATION_0];
//顯示縱向的導航欄
mCurrentView = mRotatedViews[Surface.ROTATION_90];
getImeSwitchButton().setOnClickListener(mImeSwitcherClickListener);
updateRTLOrder();
}
導航欄LayoutParams分析我們回到PhoneStatusBar的addNavigationBar繼續分析最後一個導航欄的LayoutParameters，它決定了導航欄在窗體上的顯示位置
private WindowManager.LayoutParams getNavigationBarLayoutParams() {
//充滿父布局
WindowManager.LayoutParams lp = new WindowManager.LayoutParams(
LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT,
WindowManager.LayoutParams.TYPE_NAVIGATION_BAR,//導航欄
0
| WindowManager.LayoutParams.FLAG_TOUCHABLE_WHEN_WAKING//當手機處於睡眠狀態時，如果屏幕被按下，那麼該window將第一個收到到事件
| WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE//不獲取焦點
| WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL//即使在該window在可獲得焦點情況下，仍然把該window之外的任何event發送到該window之後的其他window
| WindowManager.LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH//不接受事件，轉發到其他window
| WindowManager.LayoutParams.FLAG_SPLIT_TOUCH,//當該window在可以接受觸摸屏情況下，讓因在該window之外，而發送到後面的window的觸摸屏可以支持split touch.
PixelFormat.TRANSLUCENT);
// this will allow the navbar to run in an overlay on devices that support this
if (ActivityManager.isHighEndGfx()) {
lp.flags |= WindowManager.LayoutParams.FLAG_HARDWARE_ACCELERATED;//硬件加速
}
//lp.gravity = Gravity.RIGHT;
lp.setTitle("NavigationBar");
lp.windowAnimations = 0;
return lp;
}
上面的LayoutParames決定了導航欄在窗體的大小（受父布局影響）和顯示的位置效果，當我們的需求如果要把導航欄顯示在屏幕的右邊時，我們可以在上面代碼中加上下面一句
lp.gravity = Gravity.RIGHT;
SystemUI包含了太多內容，本篇只是分析了SystemUI的加載流程，同時初步的分析了StatusBar中一個小模塊NavigationBar，後續會針對SystemUI的其他模塊進行分析。
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