android桌面小部件appwidget使用ListView或者StackView如何刷新

系统管理员 2022-06-13 02:51 1093阅读 0赞

android的桌面小部件使用ListView和StackView刷新数据，找了半天网上了没个说明白的，自己研究了一上午，大概明白了小部件的整体机制。

如何实现StackView的小部件使用RemoteService，这些网上一堆，可以找一下。

如何刷新adapter中的数据先把结果贴上来。

使用如下方式，StackView的远端Adapter就会调用onDataSetChanged()

AppWidgetManager.getInstance(context).notifyAppWidgetViewDataChanged(entry.widgetId,R.id.appwidget_stack_view);

源码分析：

RemoteView是跑在系统进程中的，并没有在我们的App中，必须使用进程间通信才能通知真正的View来刷新。RemoteViews这个类只是个数据传输类同时还有些工具函数apply什么的，app调用upateWidget将数据传输到远端Service，之后远端就可以处理了。

OK，这里分析通知刷新，就不用反射一些方法了，直接远端调用onDataSetChanged()就可以了，看一下android是怎么调用的。

正文：

使用notifyAppWidgetViewDataChanged()方法，实际实现是在系统Service，AppWidgetServiceImpl.java中的notifyAppWidgetViewDataChanged()

@Override
        public void notifyAppWidgetViewDataChanged(String callingPackage, int[] appWidgetIds,
                int viewId) {
            final int userId = UserHandle.getCallingUserId();
    
            if (DEBUG) {
                Slog.i(TAG, "notifyAppWidgetViewDataChanged() " + userId);
            }
    
            // Make sure the package runs under the caller uid.
            mSecurityPolicy.enforceCallFromPackage(callingPackage);
    
            if (appWidgetIds == null || appWidgetIds.length == 0) {
                return;
            }
    
            synchronized (mLock) {
                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.
                    Widget widget = lookupWidgetLocked(appWidgetId,
                            Binder.getCallingUid(), callingPackage);
    
                    if (widget != null) {
                        scheduleNotifyAppWidgetViewDataChanged(widget, viewId);
                    }
                }
            }
        }

在这个方法中查找到要刷新的widget，然后scheduleNotifyAppWidgetViewDataChanged(widget, viewId);看一下这个方法。

private void scheduleNotifyAppWidgetViewDataChanged(Widget widget, int viewId) {
            if (widget == null || widget.host == null || widget.host.zombie
                    || widget.host.callbacks == null || widget.provider == null
                    || widget.provider.zombie) {
                return;
            }
    
            SomeArgs args = SomeArgs.obtain();
            args.arg1 = widget.host;
            args.arg2 = widget.host.callbacks;
            args.argi1 = widget.appWidgetId;
            args.argi2 = viewId;
    
            mCallbackHandler.obtainMessage(
                    CallbackHandler.MSG_NOTIFY_VIEW_DATA_CHANGED,
                    args).sendToTarget();
        }

将查找到的widget的一些成员变量，通过Handler发送出去了。

case MSG_NOTIFY_VIEW_DATA_CHANGED: {
                        SomeArgs args = (SomeArgs) message.obj;
                        Host host = (Host) args.arg1;
                        IAppWidgetHost callbacks = (IAppWidgetHost) args.arg2;
                        final int appWidgetId = args.argi1;
                        final int viewId = args.argi2;
                        args.recycle();
    
                        handleNotifyAppWidgetViewDataChanged(host, callbacks, appWidgetId, viewId);
                    } break;

找到Handler处理的部分，调用handleNotifyAppWidgetViewDataChanged来处理。

最后绑定AppWidget的RemoteService这个Service就是为Widget的提供Adapter的Service，只要绑定成功就就回调方法onDataSetChangedAsync()代码如下

private void handleNotifyAppWidgetViewDataChanged(Host host, IAppWidgetHost callbacks,
                int appWidgetId, int viewId) {
            try {
                callbacks.viewDataChanged(appWidgetId, viewId);
            } catch (RemoteException re) {
                // It failed; remove the callback. No need to prune because
                // we know that this host is still referenced by this instance.
                callbacks = null;
            }
    
            // If the host is unavailable, then we call the associated
            // RemoteViewsFactory.onDataSetChanged() directly
            synchronized (mLock) {
                if (callbacks == null) {
                    host.callbacks = null;
    
                    Set<Pair<Integer, FilterComparison>> keys = mRemoteViewsServicesAppWidgets.keySet();
                    for (Pair<Integer, FilterComparison> key : keys) {
                        if (mRemoteViewsServicesAppWidgets.get(key).contains(appWidgetId)) {
                            final ServiceConnection connection = new ServiceConnection() {
                                @Override
                                public void onServiceConnected(ComponentName name, IBinder service) {
                                    IRemoteViewsFactory cb = IRemoteViewsFactory.Stub
                                            .asInterface(service);
                                    try {
                                        cb.onDataSetChangedAsync();
                                    } catch (RemoteException e) {
                                        Slog.e(TAG, "Error calling onDataSetChangedAsync()", e);
                                    }
                                    mContext.unbindService(this);
                                }
    
                                @Override
                                public void onServiceDisconnected(android.content.ComponentName name) {
                                    // Do nothing
                                }
                            };
    
                            final int userId = UserHandle.getUserId(key.first);
                            Intent intent = key.second.getIntent();
    
                            // Bind to the service and call onDataSetChanged()
                            bindService(intent, connection, new UserHandle(userId));
                        }
                    }
                }
            }
        }

在RemoteViewsServices.java中

public synchronized void onDataSetChangedAsync() {
                onDataSetChanged();
            }

回调了onDataSetChanged();刷新了数据。之后就是刷新了，没有继续分析stackView源码。

总结：appWidget，使用进程间通信的方式，来刷新其他进程的View，系统Service （AppWidgetServiceImpl）处理View更新，更新时将RemoteVeiws传输到系统Service中，通过WidgetId获得对应的实际View，调用RmoteView的apply，其实就是将RemoteView中的数据，使用反射的方式，应用到实际View的对应方法中。完成实际View的更新。