Android6.0 旋轉屏幕（三）應用是否要重啓

原創 jiangnan2222 2020-02-25 10:12


上篇博客我們分析了WMS中的updateRotationUnchecked函數，當旋轉角度有變化時會調用sendNewConfiguration函數。這篇博客我們就來分析下這個函數。

  1.     public void updateRotationUnchecked(boolean alwaysSendConfiguration, boolean forceRelayout) {
  2.         if(DEBUG_ORIENTATION) Slog.v(TAG, "updateRotationUnchecked("
  3.                    + "alwaysSendConfiguration=" + alwaysSendConfiguration + ")");
  4.  
  5.         long origId = Binder.clearCallingIdentity();
  6.         boolean changed;
  7.         synchronized(mWindowMap) {
  8.             changed = updateRotationUncheckedLocked(false);
  9.             if (!changed || forceRelayout) {
  10.                 getDefaultDisplayContentLocked().layoutNeeded = true;
  11.                 performLayoutAndPlaceSurfacesLocked();
  12.             }
  13.         }
  14.  
  15.         if (changed || alwaysSendConfiguration) {
  16.             sendNewConfiguration();
  17.         }
  18.  
  19.         Binder.restoreCallingIdentity(origId);
  20.     }

AMS的updateConfiguration函數

這個函數最後是調用了AMS的updateConfiguration函數。

  1.     void sendNewConfiguration() {
  2.         try {
  3.             mActivityManager.updateConfiguration(null);
  4.         } catch (RemoteException e) {
  5.         }
  6.     }
我們再來看AMS的updateConfiguration函數，這個時候參數values是空，所以會調用WMS的computeNewConfiguration來獲取一些配置信息。然後會調用updateConfigurationLocked函數。

  1.     public void updateConfiguration(Configuration values) {
  2.         enforceCallingPermission(android.Manifest.permission.CHANGE_CONFIGURATION,
  3.                 "updateConfiguration()");
  4.  
  5.         synchronized(this) {
  6.             if (values == null && mWindowManager != null) {
  7.                 // sentinel: fetch the current configuration from the window manager
  8.                 values = mWindowManager.computeNewConfiguration();
  9.             }
  10.  
  11.             if (mWindowManager != null) {
  12.                 mProcessList.applyDisplaySize(mWindowManager);
  13.             }
  14.  
  15.             final long origId = Binder.clearCallingIdentity();
  16.             if (values != null) {
  17.                 Settings.System.clearConfiguration(values);
  18.             }
  19.             updateConfigurationLocked(values, null, false, false);
  20.             Binder.restoreCallingIdentity(origId);
  21.         }
  22.     }

我們再來看updateConfigurationLocked函數，先把Configuration數據保存在mConfiguration，然後會調用ActivityThread的scheduleConfigurationChanged。緊接着會發送ACTION_CONFIGURATION_CHANGED廣播，然後獲取當前最上面活動的Activity，調用ActivityStack的ensureActivityConfigurationLocked函數和ActivityStackSupervisor的ensureActivitiesVisibleLocked函數。

  1.     boolean updateConfigurationLocked(Configuration values,
  2.             ActivityRecord starting, boolean persistent, boolean initLocale) {
  3.         int changes = 0;
  4.  
  5.         if (values != null) {
  6.             Configuration newConfig = new Configuration(mConfiguration);
  7.             changes = newConfig.updateFrom(values);
  8.             if (changes != 0) {
  9.                 if (!initLocale && values.locale != null && values.userSetLocale) {
  10.                     final String languageTag = values.locale.toLanguageTag();
  11.                     SystemProperties.set("persist.sys.locale", languageTag);
  12.                     mHandler.sendMessage(mHandler.obtainMessage(SEND_LOCALE_TO_MOUNT_DAEMON_MSG,
  13.                             values.locale));
  14.                 }
  15.  
  16.                 mConfigurationSeq++;
  17.                 if (mConfigurationSeq <= 0) {
  18.                     mConfigurationSeq = 1;
  19.                 }
  20.                 newConfig.seq = mConfigurationSeq;
  21.                 mConfiguration = newConfig;//保存數據
  22.                 Slog.i(TAG, "Config changes=" + Integer.toHexString(changes) + " " + newConfig);
  23.                 mUsageStatsService.reportConfigurationChange(newConfig, mCurrentUserId);
  24.                 //mUsageStatsService.noteStartConfig(newConfig);
  25.  
  26.                 final Configuration configCopy = new Configuration(mConfiguration);
  27.  
  28.                 // TODO: If our config changes, should we auto dismiss any currently
  29.                 // showing dialogs?
  30.                 mShowDialogs = shouldShowDialogs(newConfig);
  31.  
  32.                 AttributeCache ac = AttributeCache.instance();
  33.                 if (ac != null) {
  34.                     ac.updateConfiguration(configCopy);
  35.                 }
  36.  
  37.                 mSystemThread.applyConfigurationToResources(configCopy);
  38.  
  39.                 if (persistent && Settings.System.hasInterestingConfigurationChanges(changes)) {
  40.                     Message msg = mHandler.obtainMessage(UPDATE_CONFIGURATION_MSG);
  41.                     msg.obj = new Configuration(configCopy);
  42.                     mHandler.sendMessage(msg);
  43.                 }
  44.  
  45.                 for (int i=mLruProcesses.size()-1; i>=0; i--) {
  46.                     ProcessRecord app = mLruProcesses.get(i);
  47.                     try {
  48.                         if (app.thread != null) {
  49.                             //調用ActivityThread的scheduleConfigurationChanged函數
  50.                             app.thread.scheduleConfigurationChanged(configCopy);
  51.                         }
  52.                     } catch (Exception e) {
  53.                     }
  54.                 }
  55.                 Intent intent = new Intent(Intent.ACTION_CONFIGURATION_CHANGED);//發送廣播
  56.                 intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY
  57.                         | Intent.FLAG_RECEIVER_REPLACE_PENDING
  58.                         | Intent.FLAG_RECEIVER_FOREGROUND);
  59.                 broadcastIntentLocked(null, null, intent, null, null, 0, null, null,
  60.                         null, AppOpsManager.OP_NONE, null, false, false,
  61.                         MY_PID, Process.SYSTEM_UID, UserHandle.USER_ALL);
  62.                 if ((changes&ActivityInfo.CONFIG_LOCALE) != 0) {
  63.                     intent = new Intent(Intent.ACTION_LOCALE_CHANGED);
  64.                     intent.addFlags(Intent.FLAG_RECEIVER_FOREGROUND);
  65.                     if (!mProcessesReady) {
  66.                         intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
  67.                     }
  68.                     broadcastIntentLocked(null, null, intent,
  69.                             null, null, 0, null, null, null, AppOpsManager.OP_NONE,
  70.                             null, false, false, MY_PID, Process.SYSTEM_UID, UserHandle.USER_ALL);
  71.                 }
  72.             }
  73.         }
  74.  
  75.         boolean kept = true;
  76.         final ActivityStack mainStack = mStackSupervisor.getFocusedStack();
  77.         // mainStack is null during startup.
  78.         if (mainStack != null) {
  79.             if (changes != 0 && starting == null) {
  80.                 // If the configuration changed, and the caller is not already
  81.                 // in the process of starting an activity, then find the top
  82.                 // activity to check if its configuration needs to change.
  83.                 starting = mainStack.topRunningActivityLocked(null);
  84.             }
  85.  
  86.             if (starting != null) {
  87.                 kept = mainStack.ensureActivityConfigurationLocked(starting, changes);
  88.                 // And we need to make sure at this point that all other activities
  89.                 // are made visible with the correct configuration.
  90.                 mStackSupervisor.ensureActivitiesVisibleLocked(starting, changes);
  91.             }
  92.         }
  93.  
  94.         if (values != null && mWindowManager != null) {
  95.             mWindowManager.setNewConfiguration(mConfiguration);
  96.         }
  97.  
  98.         return kept;
  99.     }

我們先來看看WMS的setNewConfiguration函數，主要是調用了performLayoutAndPlaceSurfacesLocked，這個函數主要是刷新系統UI和計算窗口等，我們在後續分析WMS的時候會詳細介紹。這裏就不分析了

  1.     @Override
  2.     public void setNewConfiguration(Configuration config) {
  3.         if (!checkCallingPermission(android.Manifest.permission.MANAGE_APP_TOKENS,
  4.                 "setNewConfiguration()")) {
  5.             throw new SecurityException("Requires MANAGE_APP_TOKENS permission");
  6.         }
  7.  
  8.         synchronized(mWindowMap) {
  9.             mCurConfiguration = new Configuration(config);
  10.             if (mWaitingForConfig) {
  11.                 mWaitingForConfig = false;
  12.                 mLastFinishedFreezeSource = "new-config";
  13.             }
  14.             performLayoutAndPlaceSurfacesLocked();
  15.         }
  16.     }

ActivityThread的handleConfigurationChanged

ActivityThead最後會調用到handleConfigurationChanged函數，然後會調用collectComponentCallbacks函數來統計回調，後面就調用performConfigurationChanged函數。

  1.     final void handleConfigurationChanged(Configuration config, CompatibilityInfo compat) {
  2.  
  3.         int configDiff = 0;
  4.  
  5.         synchronized (mResourcesManager) {
  6.             if (mPendingConfiguration != null) {
  7.                 if (!mPendingConfiguration.isOtherSeqNewer(config)) {
  8.                     config = mPendingConfiguration;
  9.                     mCurDefaultDisplayDpi = config.densityDpi;
  10.                     updateDefaultDensity();
  11.                 }
  12.                 mPendingConfiguration = null;
  13.             }
  14.  
  15.             if (config == null) {
  16.                 return;
  17.             }
  18.  
  19.             mResourcesManager.applyConfigurationToResourcesLocked(config, compat);
  20.  
  21.             if (mConfiguration == null) {
  22.                 mConfiguration = new Configuration();
  23.             }
  24.             if (!mConfiguration.isOtherSeqNewer(config) && compat == null) {
  25.                 return;
  26.             }
  27.  
  28.             configDiff = mConfiguration.updateFrom(config);
  29.             config = applyCompatConfiguration(mCurDefaultDisplayDpi);
  30.         }
  31.  
  32.         ArrayList<ComponentCallbacks2> callbacks = collectComponentCallbacks(false, config);
  33.  
  34.         freeTextLayoutCachesIfNeeded(configDiff);
  35.  
  36.         if (callbacks != null) {
  37.             final int N = callbacks.size();
  38.             for (int i=0; i<N; i++) {
  39.                 performConfigurationChanged(callbacks.get(i), config);
  40.             }
  41.         }
  42.     }

最後在performConfigurationChanged中會調用回調的onConfigurationChanged函數。最後也會調用到應用的Activity的onConfigurationChanged函數中。

  1.     private static void performConfigurationChanged(ComponentCallbacks2 cb, Configuration config) {
  2.         // Only for Activity objects, check that they actually call up to their
  3.         // superclass implementation.  ComponentCallbacks2 is an interface, so
  4.         // we check the runtime type and act accordingly.
  5.         Activity activity = (cb instanceof Activity) ? (Activity) cb : null;
  6.         if (activity != null) {
  7.             activity.mCalled = false;
  8.         }
  9.  
  10.         boolean shouldChangeConfig = false;
  11.         if ((activity == null) || (activity.mCurrentConfig == null)) {
  12.             shouldChangeConfig = true;
  13.         } else {
  14.  
  15.             // If the new config is the same as the config this Activity
  16.             // is already running with then don't bother calling
  17.             // onConfigurationChanged
  18.             int diff = activity.mCurrentConfig.diff(config);
  19.             if (diff != 0) {
  20.                 // If this activity doesn't handle any of the config changes
  21.                 // then don't bother calling onConfigurationChanged as we're
  22.                 // going to destroy it.
  23.                 if ((~activity.mActivityInfo.getRealConfigChanged() & diff) == 0) {
  24.                     shouldChangeConfig = true;
  25.                 }
  26.             }
  27.         }
  28.         if (shouldChangeConfig) {
  29.             cb.onConfigurationChanged(config);
  30.  
  31.             if (activity != null) {
  32.                 if (!activity.mCalled) {
  33.                     throw new SuperNotCalledException(
  34.                             "Activity " + activity.getLocalClassName() +
  35.                         " did not call through to super.onConfigurationChanged()");
  36.                 }
  37.                 activity.mConfigChangeFlags = 0;
  38.                 activity.mCurrentConfig = new Configuration(config);
  39.             }
  40.         }
  41.     }

ActivityStack的ensureActivityConfigurationLocked函數

我們繼續回到AMS的updateConfigurationLocked函數，看如下代碼，先獲取最上面的ActivityRecord，然後調用ActivityStack的ensureActivityConfigurationLocked函數。

  1.         if (mainStack != null) {
  2.             if (changes != 0 && starting == null) {
  3.                 // If the configuration changed, and the caller is not already
  4.                 // in the process of starting an activity, then find the top
  5.                 // activity to check if its configuration needs to change.
  6.                 starting = mainStack.topRunningActivityLocked(null);
  7.             }
  8.  
  9.             if (starting != null) {
  10.                 kept = mainStack.ensureActivityConfigurationLocked(starting, changes);
  11.                 // And we need to make sure at this point that all other activities
  12.                 // are made visible with the correct configuration.
  13.                 mStackSupervisor.ensureActivitiesVisibleLocked(starting, changes);
  14.             }
  15.         }

ensureActivityConfigurationLocked函數如下，先要滿足一定條件（需要在AndroidManifest.xml中配置下config change相關的配置，我們可以看下之前的博客http://blog.csdn.net/kc58236582/article/details/53665682）根據當前Activity狀態來調用relaunchActivityLocked（這個函數又會調用ActivityThread的scheduleRelaunchActivity函數重新啓動Activity）或者destroyActivityLocked函數。隨後調用ActivityThread的scheduleActivityConfigurationChanged。

  1.    final boolean ensureActivityConfigurationLocked(ActivityRecord r,
  2.             int globalChanges) {
  3.         ......
  4.  
  5.         if ((changes&(~r.info.getRealConfigChanged())) != 0 || r.forceNewConfig) {//從這句判斷知道需要在AndroidManifest中配置的
  6.             // Aha, the activity isn't handling the change, so DIE DIE DIE.
  7.             r.configChangeFlags |= changes;
  8.             r.startFreezingScreenLocked(r.app, globalChanges);
  9.             r.forceNewConfig = false;
  10.             if (r.app == null || r.app.thread == null) {
  11.                 if (DEBUG_SWITCH || DEBUG_CONFIGURATION) Slog.v(TAG_CONFIGURATION,
  12.                         "Config is destroying non-running " + r);
  13.                 destroyActivityLocked(r, true, "config");
  14.             } else if (r.state == ActivityState.PAUSING) {
  15.                 // A little annoying: we are waiting for this activity to
  16.                 // finish pausing.  Let's not do anything now, but just
  17.                 // flag that it needs to be restarted when done pausing.
  18.                 if (DEBUG_SWITCH || DEBUG_CONFIGURATION) Slog.v(TAG_CONFIGURATION,
  19.                         "Config is skipping already pausing " + r);
  20.                 r.configDestroy = true;
  21.                 return true;
  22.             } else if (r.state == ActivityState.RESUMED) {
  23.                 // Try to optimize this case: the configuration is changing
  24.                 // and we need to restart the top, resumed activity.
  25.                 // Instead of doing the normal handshaking, just say
  26.                 // "restart!".
  27.                 if (DEBUG_SWITCH || DEBUG_CONFIGURATION) Slog.v(TAG_CONFIGURATION,
  28.                         "Config is relaunching resumed " + r);
  29.                 relaunchActivityLocked(r, r.configChangeFlags, true);
  30.                 r.configChangeFlags = 0;
  31.             } else {
  32.                 if (DEBUG_SWITCH || DEBUG_CONFIGURATION) Slog.v(TAG_CONFIGURATION,
  33.                         "Config is relaunching non-resumed " + r);
  34.                 relaunchActivityLocked(r, r.configChangeFlags, false);
  35.                 r.configChangeFlags = 0;
  36.             }
  37.  
  38.             // All done...  tell the caller we weren't able to keep this
  39.             // activity around.
  40.             return false;
  41.         }
  42.  
  43.         // Default case: the activity can handle this new configuration, so hand it over.
  44.         // NOTE: We only forward the stack override configuration as the system level configuration
  45.         // changes is always sent to all processes when they happen so it can just use whatever
  46.         // system level configuration it last got.
  47.         if (r.app != null && r.app.thread != null) {
  48.             try {
  49.                 if (DEBUG_CONFIGURATION) Slog.v(TAG_CONFIGURATION, "Sending new config to " + r);
  50.                 r.app.thread.scheduleActivityConfigurationChanged(
  51.                         r.appToken, new Configuration(mOverrideConfig));
  52.             } catch (RemoteException e) {
  53.                 // If process died, whatever.
  54.             }
  55.         }
  56.         r.stopFreezingScreenLocked(false);
  57.  
  58.         return true;
  59.     }

這樣應用就會重新啓動等（完成隨系統旋轉）。



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