本文是 Android Widget（小部件）系列的第二篇，主要是从源码角度去分析非列表小部件刷新的流程。本系列的目的是通过对Android 小部件的梳理，了解小部件刷新流程、恢复流程、以及系统发生变化时，小部件是如何适配的，解决在开发小部件过程中遇到的问题。系列文章大部份来自源码的解读，内容非常多，也非常容易遗忘，因此记录分享。 # 系列文章 [ Android Widget (小部件)基础介绍以及常见问题](https://juejin.cn/post/7118683699440255013) [Android Widget (小部件)刷新源码解析一非列表](https://juejin.cn/post/7106699795225378829) [Android Widget (小部件)刷新源码解析一列表](https://juejin.cn/post/7106699795225378829) ## 一、刷新流程 1. system_process 发送广播 2. 应用widget收到广播,准备数据构建RemoteView，并调用AppWidgetManager的updateAppWidget()方法 3. AppWidgetManager 通过AIDL 通知 system_process更新，system_process收到回调后做一些列操作 4. system_process 通过AIDL 回调Host 更新方法，Host 解析RemoteView,并生成相应的视图 ## 二、详细刷新流程 ![widget 更新 -1-.png](https://p1-juejin.byteimg.com/tos-cn-i-k3u1fbpfcp/e367b65039ec4d3a99de89c069cfe95d~tplv-k3u1fbpfcp-watermark.image?) ``` 1、system_process 发送广播更新广播的action 为android.appwidget.action.APPWIDGET_UPDATE 2、updateAppWidget()/partiallyUpdateAppWidget 局部更新调用AppWidgetManager.updateAppWidget(),在此之前一般都会设置相应的RemoteView 3、updateAppWidgetIds() 这里通过AIDL跨进程技术调用system_progress进程的AppWidgetServiceImpl对象。 3.1、enforceCallFromPackage() 安全性校验，确定请求的包命和uid 是一致的 3.2、ensureGroupStateLoadedLocked 若已经加载过了则return,若没有加载过则根据uid 获取widgetProvider(过滤带刷新action 的广播)，根据uid 获取相应的配置文件，根据配置文件设置widget，并绑定相应的host。放入mWidgets中。 3.3、lookupWidgetLocked 根据widgetId在mWidgets 找到对应的widget,通过uid验证权限 3.4、updateAppWidgetInstanceLocked 替换widget 的remoteView（局部刷新是合并两次的RemoteView），检查RemoteView的bitmap 是否超过最大限制。 3.4.1、scheduleNotifyUpdateAppWidgetLocked mCallbackHandler 发送更新message 3.5、handleNotifyUpdateAppWidget host 的 updateAppWidget()方法 4、通过AIDL 回调Host 的updateAppWidget( )，send 更新 message 4.1、handler 处理更新message 4.1.1、updateAppWidgetView 在host的mViews中通过widgetId 找到对应的AppWidgetHostView,让后进行更新 4.1.1.1、applyRemoteViews将remoteView 中的action 设置在相应view 上 ``` ## 三、详细刷新流程代码分析 1、system_process 发送广播，更新广播的action 为android.appwidget.action.APPWIDGET_UPDATE。 ``` // AppWidgetProvider 继承于广播，system_process发送广播是会回调onReceive方法 // 如果是更新广播的话会回调onUpdate（）方法 public class AppWidgetProvider extends BroadcastReceiver { ... public void onReceive(Context context, Intent intent) { // Protect against rogue update broadcasts (not really a security issue, // just filter bad broacasts out so subclasses are less likely to crash). String action = intent.getAction(); if (AppWidgetManager.ACTION_APPWIDGET_UPDATE.equals(action)) { Bundle extras = intent.getExtras(); if (extras != null) { int[] appWidgetIds = extras.getIntArray(AppWidgetManager.EXTRA_APPWIDGET_IDS); if (appWidgetIds != null && appWidgetIds.length > 0) { this.onUpdate(context, AppWidgetManager.getInstance(context), appWidgetIds); } } } ... } ``` 2、应用widget收到广播,准备数据构建RemoteView，并调用AppWidgetManager的updateAppWidget()方法 ``` public abstract class TestWidgetProvider extends AppWidgetProvider { ... /** *onReceive会回调该方法 * **/ @Override public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds{ // AppWidgetProvider 这里通常会设置new RemoteView,并设置，可设置点击时间、文字、图片等最后调用 // appWidgetManager.updateAppWidget() super.onUpdate(context, appWidgetManager, appWidgetIds); for (int widgetId : appWidgetIds) { RemoteViews remoteViews = new RemoteViews(context.getPackageName(), R.layout.widget_test); ... appWidgetManager.updateAppWidget(widgetId, remoteViews); } } ... } ``` 3、updateAppWidgetIds（）方法，这里通过AIDL跨进程技术调用system_progress进程的AppWidgetServiceImpl对象。 ``` public class AppWidgetManager { ... public void updateAppWidget(int[] appWidgetIds, RemoteViews views) { mService 为 AppWidgetServiceImpl if (mService == null) { return; } try { // 通过AIDL 调用 AppWidgetServiceImpl 的 mService.updateAppWidgetIds 方法 mService.updateAppWidgetIds(mPackageName, appWidgetIds, views); } catch (RemoteException e) { throw e.rethrowFromSystemServer(); } } ... } // partially 代表是否部分更新 private void updateAppWidgetIds(String callingPackage, int[] appWidgetIds, RemoteViews views, boolean partially) { final int userId = UserHandle.getCallingUserId(); if (appWidgetIds == null || appWidgetIds.length == 0) { return; } // Make sure the package runs under the caller uid. // AppWidgetServiceImpl 运行在system_process ，包名为字符串传入， // 安全性校验，确定请求的包命和uid 是一致的 mSecurityPolicy.enforceCallFromPackage(callingPackage); synchronized (mLock) { // 是否解锁状态，处于解锁状态，若第一次加载则构建widget，后面会详细解析 ensureGroupStateLoadedLocked(userId); final int N = appWidgetIds.length; for (int i = 0; i < N; i++) { final int appWidgetId = appWidgetIds[i]; // NOTE: The lookup is enforcing security across users by making // sure the caller can only access widgets it hosts or provides. // 根据widgetId在mWidgets 找到对应的widget,通过uid验证权限,后面会详细解析 Widget widget = lookupWidgetLocked(appWidgetId, Binder.getCallingUid(), callingPackage); if (widget != null) { // 更新widget updateAppWidgetInstanceLocked(widget, views, partially); } } } } ``` 3.1、enforceCallFromPackage（）方法，安全性校验，确定请求的包命和uid 是一致的。 ``` public void enforceCallFromPackage(String packageName) { mAppOpsManager.checkPackage(Binder.getCallingUid(), packageName); } @Deprecated public void checkPackage(int uid, @NonNull String packageName) { try { // 检查请求的 uid 和 packageName 是否一致 if (mService.checkPackage(uid, packageName) != MODE_ALLOWED) { throw new SecurityException( "Package " + packageName + " does not belong to " + uid); } } catch (RemoteException e) { throw e.rethrowFromSystemServer(); } } ``` 3.2、ensureGroupStateLoadedLocked（）方法，若已经加载过了则return,若没有加载过则根据uid 获取widgetProvider(过滤带刷新action 的广播)，根据uid 获取相应的配置文件，根据配置文件设置widget，并绑定相应的host。放入mWidgets中。 ``` private void ensureGroupStateLoadedLocked(int userId, boolean enforceUserUnlockingOrUnlocked) { // 判断该应用是否处在解锁状态，设备锁 if (enforceUserUnlockingOrUnlocked && !isUserRunningAndUnlocked(userId)) { throw new IllegalStateException( "User " + userId + " must be unlocked for widgets to be available"); } // 判断该应用文件配置是否处在解锁状态 if (enforceUserUnlockingOrUnlocked && isProfileWithLockedParent(userId)) { throw new IllegalStateException( "Profile " + userId + " must have unlocked parent"); } // 获取能用的配置配置id final int[] profileIds = mSecurityPolicy.getEnabledGroupProfileIds(userId); // 查看是否有未加载的user https://www.jianshu.com/p/3ad2163f7d34 //https://blog.csdn.net/qq_14978113/article/details/94654401 // Careful lad, we may have already loaded the state for some // group members, so check before loading and read only the // state for the new member(s). int newMemberCount = 0; final int profileIdCount = profileIds.length; for (int i = 0; i < profileIdCount; i++) { final int profileId = profileIds[i]; // >=0代表已经加载过,标记数组 if (mLoadedUserIds.indexOfKey(profileId) >= 0) { profileIds[i] = LOADED_PROFILE_ID; } else { newMemberCount++; } } // 没有新加的便会return if (newMemberCount <= 0) { return; } // 构建新增加的ProfileId 数组,后续通常在第一次加载的时候执行 int newMemberIndex = 0; final int[] newProfileIds = new int[newMemberCount]; for (int i = 0; i < profileIdCount; i++) { final int profileId = profileIds[i]; if (profileId != LOADED_PROFILE_ID) { mLoadedUserIds.put(profileId, profileId); newProfileIds[newMemberIndex] = profileId; newMemberIndex++; } } // 清除provider 和 host 的tag 设置为 TAG_UNDEFINED clearProvidersAndHostsTagsLocked(); // 根据加载ProfileId 获取系统 ResolveInfo 列表，根据ResolveInfo 构建 provider; loadGroupWidgetProvidersLocked(newProfileIds); // 从系统配置文件/data/system/users/0/appwidgets.xml 加载状态、 loadGroupStateLocked(newProfileIds); } ``` 3.3、lookupWidgetLocked（）方法，根据widgetId在mWidgets 找到对应的widget,通过uid验证权限。 ``` private Widget lookupWidgetLocked(int appWidgetId, int uid, String packageName) { final int N = mWidgets.size(); for (int i = 0; i < N; i++) { Widget widget = mWidgets.get(i); if (widget.appWidgetId == appWidgetId && mSecurityPolicy.canAccessAppWidget(widget, uid, packageName)) { return widget; } } return null; } ``` 3.4、updateAppWidgetInstanceLocked（）方法，替换widget 的remoteView（局部刷新是合并两次的RemoteView），检查RemoteView的bitmap 是否超过最大限制。 ``` private void updateAppWidgetInstanceLocked(Widget widget, RemoteViews views, boolean isPartialUpdate) { if (widget != null && widget.provider != null && !widget.provider.zombie && !widget.host.zombie) { // 如果是局部更新，合并remote view if (isPartialUpdate && widget.views != null) { // For a partial update, we merge the new RemoteViews with the old. widget.views.mergeRemoteViews(views); } else { // For a full update we replace the RemoteViews completely. widget.views = views; } // 如果非系统应用 bitmap 的大小超过规定大小，则抛出异常 int memoryUsage; if ((UserHandle.getAppId(Binder.getCallingUid()) != Process.SYSTEM_UID) && (widget.views != null) && ((memoryUsage = widget.views.estimateMemoryUsage()) > mMaxWidgetBitmapMemory)) { widget.views = null; throw new IllegalArgumentException("RemoteViews for widget update exceeds" + " maximum bitmap memory usage (used: " + memoryUsage + ", max: " + mMaxWidgetBitmapMemory + ")"); } scheduleNotifyUpdateAppWidgetLocked(widget, widget.getEffectiveViewsLocked()); } } /*** **合并action **/ @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553) public void mergeRemoteViews(RemoteViews newRv) { if (newRv == null) return; // We first copy the new RemoteViews, as the process of merging modifies the way the actions // reference the bitmap cache. We don't want to modify the object as it may need to // be merged and applied multiple times. RemoteViews copy = new RemoteViews(newRv); HashMap map = new HashMap(); if (mActions == null) { mActions = new ArrayList(); } // 将老的action 放入map int count = mActions.size(); for (int i = 0; i < count; i++) { Action a = mActions.get(i); map.put(a.getUniqueKey(), a); } ArrayList newActions = copy.mActions; if (newActions == null) return; count = newActions.size(); for (int i = 0; i < count; i++) { Action a = newActions.get(i); //由viewId和action tag 组成 String key = newActions.get(i).getUniqueKey(); // R开始支持 int mergeBehavior = newActions.get(i).mergeBehavior(); // 相同则把旧的action 移除 if (map.containsKey(key) && mergeBehavior == Action.MERGE_REPLACE) { mActions.remove(map.get(key)); map.remove(key); } // If the merge behavior is ignore, we don't bother keeping the extra action if (mergeBehavior == Action.MERGE_REPLACE || mergeBehavior == Action.MERGE_APPEND) { mActions.add(a); } } 存储设置的bitmap // Because pruning can remove the need for bitmaps, we reconstruct the bitmap cache mBitmapCache = new BitmapCache(); setBitmapCache(mBitmapCache); } ``` 3.4.1、scheduleNotifyUpdateAppWidgetLocked（）方法，mCallbackHandler 发送更新message。 ``` private void scheduleNotifyUpdateAppWidgetLocked(Widget widget, RemoteViews updateViews) { long requestId = UPDATE_COUNTER.incrementAndGet(); if (widget != null) { widget.updateSequenceNos.put(ID_VIEWS_UPDATE, requestId); } if (widget == null || widget.provider == null || widget.provider.zombie || widget.host.callbacks == null || widget.host.zombie) { return; } SomeArgs args = SomeArgs.obtain(); args.arg1 = widget.host; args.arg2 = widget.host.callbacks; args.arg3 = (updateViews != null) ? updateViews.clone() : null; args.arg4 = requestId; args.argi1 = widget.appWidgetId; mCallbackHandler.obtainMessage( CallbackHandler.MSG_NOTIFY_UPDATE_APP_WIDGET, args).sendToTarget(); } ``` 3.5、handleNotifyUpdateAppWidget（）方法，host 的 updateAppWidget()方法，通过通过AIDL 回调到host 中。 ``` private void handleNotifyUpdateAppWidget(Host host, IAppWidgetHost callbacks, int appWidgetId, RemoteViews views, long requestId) { try { callbacks.updateAppWidget(appWidgetId, views); host.lastWidgetUpdateSequenceNo = requestId; } catch (RemoteException re) { synchronized (mLock) { Slog.e(TAG, "Widget host dead: " + host.id, re); host.callbacks = null; } } } ``` 4、通过AIDL 回调Host 的updateAppWidget( )，send 更新 message ``` public class AppWidgetHost { public void updateAppWidget(int appWidgetId, RemoteViews views) { if (isLocalBinder() && views != null) { views = views.clone(); } Handler handler = mWeakHandler.get(); if (handler == null) { return; } Message msg = handler.obtainMessage(HANDLE_UPDATE, appWidgetId, 0, views); msg.sendToTarget(); } } ``` 4.1、handler 处理更新message。 ``` public void handleMessage(Message msg) { switch (msg.what) { case HANDLE_UPDATE: { updateAppWidgetView(msg.arg1, (RemoteViews)msg.obj); break; } } } ``` 4.1.1、updateAppWidgetView（）方法，在host的mViews中通过widgetId 找到对应的AppWidgetHostView,让后进行更新。 ``` void updateAppWidgetView(int appWidgetId, RemoteViews views) { AppWidgetHostView v; synchronized (mViews) { v = mViews.get(appWidgetId); } if (v != null) { v.updateAppWidget(views); } } ``` 4.1.1.1、applyRemoteViews（）方法，将remoteView 中的action 设置在相应view 上。 ``` protected void applyRemoteViews(@Nullable RemoteViews remoteViews, boolean useAsyncIfPossible) { boolean recycled = false; View content = null; Exception exception = null; // Block state restore until the end of the apply. mLastInflatedRemoteViewsId = -1; if (mLastExecutionSignal != null) { mLastExecutionSignal.cancel(); mLastExecutionSignal = null; } // 如果remoteViews 为null 加载默认视图 if (remoteViews == null) { if (mViewMode == VIEW_MODE_DEFAULT) { // We've already done this -- nothing to do. return; } content = getDefaultView(); mLayoutId = -1; mViewMode = VIEW_MODE_DEFAULT; } else { // Select the remote view we are actually going to apply. // 查找适合的remoteView 找不到时返回最小的 RemoteViews rvToApply = remoteViews.getRemoteViewsToApply(mContext, mCurrentSize); // 是否设置了 /if (mOnLightBackground) { // 如果深色浅色模式变了，使用相应的 layout id ,new remoteview rvToApply = rvToApply.getDarkTextViews(); } if (mAsyncExecutor != null && useAsyncIfPossible) { // 异步加载 inflateAsync(rvToApply); return; } int layoutId = rvToApply.getLayoutId(); if (rvToApply.canRecycleView(mView)) { try { rvToApply.reapply(mContext, mView, mInteractionHandler, mCurrentSize, mColorResources); content = mView; mLastInflatedRemoteViewsId = rvToApply.computeUniqueId(remoteViews); recycled = true; if (LOGD) Log.d(TAG, "was able to recycle existing layout"); } catch (RuntimeException e) { exception = e; } } // Try normal RemoteView inflation if (content == null) { try { content = rvToApply.apply(mContext, this, mInteractionHandler, mCurrentSize, mColorResources); mLastInflatedRemoteViewsId = rvToApply.computeUniqueId(remoteViews); if (LOGD) Log.d(TAG, "had to inflate new layout"); } catch (RuntimeException e) { exception = e; } } mLayoutId = layoutId; mViewMode = VIEW_MODE_CONTENT; } applyContent(content, recycled, exception); } /** **将action 转成相应的设置 **/ private void reapply(Context context, View v, InteractionHandler handler, SizeF size, ColorResources colorResources, boolean topLevel) { RemoteViews rvToApply = getRemoteViewsToApply(context, size); // In the case that a view has this RemoteViews applied in one orientation or size, is // persisted across change, and has the RemoteViews re-applied in a different situation // (orientation or size), we throw an exception, since the layouts may be completely // unrelated. if (hasMultipleLayouts()) { if (!rvToApply.canRecycleView(v)) { throw new RuntimeException("Attempting to re-apply RemoteViews to a view that" + " that does not share the same root layout id."); } } // 将action 转成相应行为 rvToApply.performApply(v, (ViewGroup) v.getParent(), handler, colorResources); // If the parent of the view is has is a root, resolve the recycling. if (topLevel && v instanceof ViewGroup) { finalizeViewRecycling((ViewGroup) v); } } /** **将生成的view 添加到host 中 **/ private void applyContent(View content, boolean recycled, Exception exception) { if (content == null) { if (mViewMode == VIEW_MODE_ERROR) { // We've already done this -- nothing to do. return ; } if (exception != null) { Log.w(TAG, "Error inflating RemoteViews", exception); } content = getErrorView(); mViewMode = VIEW_MODE_ERROR; } // 复用的场景直接在view上进行了设置，而view 之前已经添加到host，所以复用的case 这里就不用处理。 if (!recycled) { prepareView(content); addView(content); } if (mView != content) { removeView(mView); mView = content; } } ``` 到这里，非列表小部件的刷新就梳理完了。里面涉及到很多东西，比如跨进程通信、安全性校验、多用户、分身等，但如果这些不是你关注的，可以选择忽略，因为并耽误你去理解刷新的整个过程。**最后提醒一下刷新是一个跨进程的操作，因此最好在子线程中调用。**