Android example source code file (AccessibilityManagerService.java)

This example Android source code file (AccessibilityManagerService.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

accessibility, accessibilityevent, accessibilitymanagerservice, android, arraylist, componentname, content, contentobserver, dead, error, handler, list, os, override, remoteexception, service, set, string, util, view

The AccessibilityManagerService.java Android example source code

/*
 ** Copyright 2009, The Android Open Source Project
 **
 ** Licensed under the Apache License, Version 2.0 (the "License");
 ** you may not use this file except in compliance with the License.
 ** You may obtain a copy of the License at
 **
 **     http://www.apache.org/licenses/LICENSE-2.0
 **
 ** Unless required by applicable law or agreed to in writing, software
 ** distributed under the License is distributed on an "AS IS" BASIS,
 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 ** See the License for the specific language governing permissions and
 ** limitations under the License.
 */

package com.android.server;

import com.android.internal.content.PackageMonitor;
import com.android.internal.os.HandlerCaller;
import com.android.internal.os.HandlerCaller.SomeArgs;

import android.accessibilityservice.AccessibilityService;
import android.accessibilityservice.AccessibilityServiceInfo;
import android.accessibilityservice.IAccessibilityServiceConnection;
import android.accessibilityservice.IEventListener;
import android.app.PendingIntent;
import android.content.BroadcastReceiver;
import android.content.ComponentName;
import android.content.ContentResolver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.ServiceConnection;
import android.content.pm.PackageManager;
import android.content.pm.ResolveInfo;
import android.content.pm.ServiceInfo;
import android.database.ContentObserver;
import android.net.Uri;
import android.os.Binder;
import android.os.DeadObjectException;
import android.os.Handler;
import android.os.IBinder;
import android.os.Message;
import android.os.RemoteException;
import android.provider.Settings;
import android.text.TextUtils;
import android.text.TextUtils.SimpleStringSplitter;
import android.util.Config;
import android.util.Slog;
import android.util.SparseArray;
import android.view.accessibility.AccessibilityEvent;
import android.view.accessibility.IAccessibilityManager;
import android.view.accessibility.IAccessibilityManagerClient;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

/**
 * This class is instantiated by the system as a system level service and can be
 * accessed only by the system. The task of this service is to be a centralized
 * event dispatch for {@link AccessibilityEvent}s generated across all processes
 * on the device. Events are dispatched to {@link AccessibilityService}s.
 *
 * @hide
 */
public class AccessibilityManagerService extends IAccessibilityManager.Stub
        implements HandlerCaller.Callback {

    private static final String LOG_TAG = "AccessibilityManagerService";

    private static int sIdCounter = 0;

    private static final int OWN_PROCESS_ID = android.os.Process.myPid();

    private static final int DO_SET_SERVICE_INFO = 10;

    final HandlerCaller mCaller;

    final Context mContext;

    final Object mLock = new Object();

    final List<Service> mServices = new ArrayList();

    final List<IAccessibilityManagerClient> mClients =
        new ArrayList<IAccessibilityManagerClient>();

    final Map<ComponentName, Service> mComponentNameToServiceMap =
        new HashMap<ComponentName, Service>();

    private final List<ServiceInfo> mInstalledServices = new ArrayList();

    private final Set<ComponentName> mEnabledServices = new HashSet();

    private final SimpleStringSplitter mStringColonSplitter = new SimpleStringSplitter(':');

    private PackageManager mPackageManager;

    private int mHandledFeedbackTypes = 0;

    private boolean mIsEnabled;

    /**
     * Handler for delayed event dispatch.
     */
    private Handler mHandler = new Handler() {

        @Override
        public void handleMessage(Message message) {
            Service service = (Service) message.obj;
            int eventType = message.arg1;

            synchronized (mLock) {
                notifyEventListenerLocked(service, eventType);
                AccessibilityEvent oldEvent = service.mPendingEvents.get(eventType);
                service.mPendingEvents.remove(eventType);
                tryRecycleLocked(oldEvent);
            }
        }
    };

    /**
     * Creates a new instance.
     *
     * @param context A {@link Context} instance.
     */
    AccessibilityManagerService(Context context) {
        mContext = context;
        mPackageManager = mContext.getPackageManager();
        mCaller = new HandlerCaller(context, this);

        registerPackageChangeAndBootCompletedBroadcastReceiver();
        registerSettingsContentObservers();
    }

    /**
     * Registers a {@link BroadcastReceiver} for the events of
     * adding/changing/removing/restarting a package and boot completion.
     */
    private void registerPackageChangeAndBootCompletedBroadcastReceiver() {
        Context context = mContext;

        PackageMonitor monitor = new PackageMonitor() {
            @Override
            public void onSomePackagesChanged() {
                synchronized (mLock) {
                    populateAccessibilityServiceListLocked();
                    manageServicesLocked();
                }
            }
            
            @Override
            public boolean onHandleForceStop(Intent intent, String[] packages,
                    int uid, boolean doit) {
                synchronized (mLock) {
                    boolean changed = false;
                    Iterator<ComponentName> it = mEnabledServices.iterator();
                    while (it.hasNext()) {
                        ComponentName comp = it.next();
                        String compPkg = comp.getPackageName();
                        for (String pkg : packages) {
                            if (compPkg.equals(pkg)) {
                                if (!doit) {
                                    return true;
                                }
                                it.remove();
                                changed = true;
                            }
                        }
                    }
                    if (changed) {
                        it = mEnabledServices.iterator();
                        StringBuilder str = new StringBuilder();
                        while (it.hasNext()) {
                            if (str.length() > 0) {
                                str.append(':');
                            }
                            str.append(it.next().flattenToShortString());
                        }
                        Settings.Secure.putString(mContext.getContentResolver(),
                                Settings.Secure.ENABLED_ACCESSIBILITY_SERVICES,
                                str.toString());
                        manageServicesLocked();
                    }
                    return false;
                }
            }
            
            @Override
            public void onReceive(Context context, Intent intent) {
                if (intent.getAction() == Intent.ACTION_BOOT_COMPLETED) {
                    synchronized (mLock) {
                        populateAccessibilityServiceListLocked();

                        // get the accessibility enabled setting on boot
                        mIsEnabled = Settings.Secure.getInt(mContext.getContentResolver(),
                                Settings.Secure.ACCESSIBILITY_ENABLED, 0) == 1;

                        // if accessibility is enabled inform our clients we are on
                        if (mIsEnabled) {
                            updateClientsLocked();
                        }

                        manageServicesLocked();
                    }
                    
                    return;
                }
                
                super.onReceive(context, intent);
            }
        };

        // package changes
        monitor.register(context, true);

        // boot completed
        IntentFilter bootFiler = new IntentFilter(Intent.ACTION_BOOT_COMPLETED);
        mContext.registerReceiver(monitor, bootFiler);
    }

    /**
     * {@link ContentObserver}s for {@link Settings.Secure#ACCESSIBILITY_ENABLED}
     * and {@link Settings.Secure#ENABLED_ACCESSIBILITY_SERVICES} settings.
     */
    private void registerSettingsContentObservers() {
        ContentResolver contentResolver = mContext.getContentResolver();

        Uri enabledUri = Settings.Secure.getUriFor(Settings.Secure.ACCESSIBILITY_ENABLED);
        contentResolver.registerContentObserver(enabledUri, false,
            new ContentObserver(new Handler()) {
                @Override
                public void onChange(boolean selfChange) {
                    super.onChange(selfChange);

                    mIsEnabled = Settings.Secure.getInt(mContext.getContentResolver(),
                        Settings.Secure.ACCESSIBILITY_ENABLED, 0) == 1;

                    synchronized (mLock) {
                        if (mIsEnabled) {
                            manageServicesLocked();
                        } else {
                            unbindAllServicesLocked();
                        }
                        updateClientsLocked();
                    }
                }
            });

        Uri providersUri =
            Settings.Secure.getUriFor(Settings.Secure.ENABLED_ACCESSIBILITY_SERVICES);
        contentResolver.registerContentObserver(providersUri, false,
            new ContentObserver(new Handler()) {
                @Override
                public void onChange(boolean selfChange) {
                    super.onChange(selfChange);

                    synchronized (mLock) {
                        manageServicesLocked();
                    }
                }
            });
    }

    public void addClient(IAccessibilityManagerClient client) {
        synchronized (mLock) {
            try {
                client.setEnabled(mIsEnabled);
                mClients.add(client);
            } catch (RemoteException re) {
                Slog.w(LOG_TAG, "Dead AccessibilityManagerClient: " + client, re);
            }
        }
    }

    public boolean sendAccessibilityEvent(AccessibilityEvent event) {
        synchronized (mLock) {
            notifyAccessibilityServicesDelayedLocked(event, false);
            notifyAccessibilityServicesDelayedLocked(event, true);
        }
        // event not scheduled for dispatch => recycle
        if (mHandledFeedbackTypes == 0) {
            event.recycle();
        } else {
            mHandledFeedbackTypes = 0;
        }

        return (OWN_PROCESS_ID != Binder.getCallingPid());
    }

    public List<ServiceInfo> getAccessibilityServiceList() {
        synchronized (mLock) {
            return mInstalledServices;
        }
    }

    public void interrupt() {
        synchronized (mLock) {
            for (int i = 0, count = mServices.size(); i < count; i++) {
                Service service = mServices.get(i);
                try {
                    service.mServiceInterface.onInterrupt();
                } catch (RemoteException re) {
                    if (re instanceof DeadObjectException) {
                        Slog.w(LOG_TAG, "Dead " + service.mService + ". Cleaning up.");
                        if (removeDeadServiceLocked(service)) {
                            count--;
                            i--;
                        }
                    } else {
                        Slog.e(LOG_TAG, "Error during sending interrupt request to "
                                + service.mService, re);
                    }
                }
            }
        }
    }

    public void executeMessage(Message message) {
        switch (message.what) {
            case DO_SET_SERVICE_INFO:
                SomeArgs arguments = ((SomeArgs) message.obj);

                AccessibilityServiceInfo info = (AccessibilityServiceInfo) arguments.arg1;
                Service service = (Service) arguments.arg2;

                synchronized (mLock) {
                    service.mEventTypes = info.eventTypes;
                    service.mFeedbackType = info.feedbackType;
                    String[] packageNames = info.packageNames;
                    if (packageNames != null) {
                        service.mPackageNames.addAll(Arrays.asList(packageNames));
                    }
                    service.mNotificationTimeout = info.notificationTimeout;
                    service.mIsDefault = (info.flags & AccessibilityServiceInfo.DEFAULT) != 0;
                }
                return;
            default:
                Slog.w(LOG_TAG, "Unknown message type: " + message.what);
        }
    }

    /**
     * Populates the cached list of installed {@link AccessibilityService}s.
     */
    private void populateAccessibilityServiceListLocked() {
        mInstalledServices.clear();

        List<ResolveInfo> installedServices = mPackageManager.queryIntentServices(
                new Intent(AccessibilityService.SERVICE_INTERFACE), PackageManager.GET_SERVICES);

        for (int i = 0, count = installedServices.size(); i < count; i++) {
            mInstalledServices.add(installedServices.get(i).serviceInfo);
        }
    }

    /**
     * Performs {@link AccessibilityService}s delayed notification. The delay is configurable
     * and denotes the period after the last event before notifying the service.
     *
     * @param event The event.
     * @param isDefault True to notify default listeners, not default services.
     */
    private void notifyAccessibilityServicesDelayedLocked(AccessibilityEvent event,
            boolean isDefault) {
        try {
            for (int i = 0, count = mServices.size(); i < count; i++) {
                Service service = mServices.get(i);

                if (service.mIsDefault == isDefault) {
                    if (canDispathEventLocked(service, event, mHandledFeedbackTypes)) {
                        mHandledFeedbackTypes |= service.mFeedbackType;
                        notifyAccessibilityServiceDelayedLocked(service, event);
                    }
                }
            }
        } catch (IndexOutOfBoundsException oobe) {
            // An out of bounds exception can happen if services are going away
            // as the for loop is running. If that happens, just bail because
            // there are no more services to notify.
            return;
        }
    }

    /**
     * Performs an {@link AccessibilityService} delayed notification. The delay is configurable
     * and denotes the period after the last event before notifying the service.
     *
     * @param service The service.
     * @param event The event.
     */
    private void notifyAccessibilityServiceDelayedLocked(Service service,
            AccessibilityEvent event) {
        synchronized (mLock) {
            int eventType = event.getEventType();
            AccessibilityEvent oldEvent = service.mPendingEvents.get(eventType);
            service.mPendingEvents.put(eventType, event);

            int what = eventType | (service.mId << 16);
            if (oldEvent != null) {
                mHandler.removeMessages(what);
                tryRecycleLocked(oldEvent);
            }

            Message message = mHandler.obtainMessage(what, service);
            message.arg1 = event.getEventType();
            mHandler.sendMessageDelayed(message, service.mNotificationTimeout);
        }
    }

    /**
     * Recycles an event if it can be safely recycled. The condition is that no
     * not notified service is interested in the event.
     *
     * @param event The event.
     */
    private void tryRecycleLocked(AccessibilityEvent event) {
        if (event == null) {
            return;
        }
        int eventType = event.getEventType();
        List<Service> services = mServices;

        // linear in the number of service which is not large
        for (int i = 0, count = services.size(); i < count; i++) {
            Service service = services.get(i);
            if (service.mPendingEvents.get(eventType) == event) {
                return;
            }
        }
        event.recycle();
    }

    /**
     * Notifies a service for a scheduled event given the event type.
     *
     * @param service The service.
     * @param eventType The type of the event to dispatch.
     */
    private void notifyEventListenerLocked(Service service, int eventType) {
        IEventListener listener = service.mServiceInterface;
        AccessibilityEvent event = service.mPendingEvents.get(eventType);

        try {
            listener.onAccessibilityEvent(event);
            if (Config.DEBUG) {
                Slog.i(LOG_TAG, "Event " + event + " sent to " + listener);
            }
        } catch (RemoteException re) {
            if (re instanceof DeadObjectException) {
                Slog.w(LOG_TAG, "Dead " + service.mService + ". Cleaning up.");
                synchronized (mLock) {
                    removeDeadServiceLocked(service);
                }
            } else {
                Slog.e(LOG_TAG, "Error during sending " + event + " to " + service.mService, re);
            }
        }
    }

    /**
     * Removes a dead service.
     *
     * @param service The service.
     * @return True if the service was removed, false otherwise.
     */
    private boolean removeDeadServiceLocked(Service service) {
        mServices.remove(service);
        mHandler.removeMessages(service.mId);

        if (Config.DEBUG) {
            Slog.i(LOG_TAG, "Dead service " + service.mService + " removed");
        }

        if (mServices.isEmpty()) {
            mIsEnabled = false;
            updateClientsLocked();
        }

        return true;
    }

    /**
     * Determines if given event can be dispatched to a service based on the package of the
     * event source and already notified services for that event type. Specifically, a
     * service is notified if it is interested in events from the package and no other service
     * providing the same feedback type has been notified. Exception are services the
     * provide generic feedback (feedback type left as a safety net for unforeseen feedback
     * types) which are always notified.
     *
     * @param service The potential receiver.
     * @param event The event.
     * @param handledFeedbackTypes The feedback types for which services have been notified.
     * @return True if the listener should be notified, false otherwise.
     */
    private boolean canDispathEventLocked(Service service, AccessibilityEvent event,
            int handledFeedbackTypes) {

        if (!service.isConfigured()) {
            return false;
        }

        if (!service.mService.isBinderAlive()) {
            removeDeadServiceLocked(service);
            return false;
        }

        int eventType = event.getEventType();
        if ((service.mEventTypes & eventType) != eventType) {
            return false;
        }

        Set<String> packageNames = service.mPackageNames;
        CharSequence packageName = event.getPackageName();

        if (packageNames.isEmpty() || packageNames.contains(packageName)) {
            int feedbackType = service.mFeedbackType;
            if ((handledFeedbackTypes & feedbackType) != feedbackType
                    || feedbackType == AccessibilityServiceInfo.FEEDBACK_GENERIC) {
                return true;
            }
        }

        return false;
    }

    /**
     * Manages services by starting enabled ones and stopping disabled ones.
     */
    private void manageServicesLocked() {
        populateEnabledServicesLocked(mEnabledServices);
        updateServicesStateLocked(mInstalledServices, mEnabledServices);
    }

    /**
     * Unbinds all bound services.
     */
    private void unbindAllServicesLocked() {
        List<Service> services = mServices;

        for (int i = 0, count = services.size(); i < count; i++) {
            Service service = services.get(i);

            service.unbind();
            mComponentNameToServiceMap.remove(service.mComponentName);
        }
        services.clear();
    }

    /**
     * Populates a list with the {@link ComponentName}s of all enabled
     * {@link AccessibilityService}s.
     *
     * @param enabledServices The list.
     */
    private void populateEnabledServicesLocked(Set<ComponentName> enabledServices) {
        enabledServices.clear();

        String servicesValue = Settings.Secure.getString(mContext.getContentResolver(),
                Settings.Secure.ENABLED_ACCESSIBILITY_SERVICES);

        if (servicesValue != null) {
            TextUtils.SimpleStringSplitter splitter = mStringColonSplitter;
            splitter.setString(servicesValue);
            while (splitter.hasNext()) {
                String str = splitter.next();
                if (str == null || str.length() <= 0) {
                    continue;
                }
                ComponentName enabledService = ComponentName.unflattenFromString(str);
                if (enabledService != null) {
                    enabledServices.add(enabledService);
                }
            }
        }
    }

    /**
     * Updates the state of each service by starting (or keeping running) enabled ones and
     * stopping the rest.
     *
     * @param installedServices All installed {@link AccessibilityService}s.
     * @param enabledServices The {@link ComponentName}s of the enabled services.
     */
    private void updateServicesStateLocked(List<ServiceInfo> installedServices,
            Set<ComponentName> enabledServices) {

        Map<ComponentName, Service> componentNameToServiceMap = mComponentNameToServiceMap;
        List<Service> services = mServices;
        boolean isEnabled = mIsEnabled;

        for (int i = 0, count = installedServices.size(); i < count; i++) {
            ServiceInfo intalledService = installedServices.get(i);
            ComponentName componentName = new ComponentName(intalledService.packageName,
                    intalledService.name);
            Service service = componentNameToServiceMap.get(componentName);

            if (isEnabled && enabledServices.contains(componentName)) {
                if (service == null) {
                    new Service(componentName).bind();
                }
            } else {
                if (service != null) {
                    service.unbind();
                    componentNameToServiceMap.remove(componentName);
                    services.remove(service);
                }
            }
        }
    }

    /**
     * Updates the state of {@link android.view.accessibility.AccessibilityManager} clients.
     */
    private void updateClientsLocked() {
        for (int i = 0, count = mClients.size(); i < count; i++) {
            try {
                mClients.get(i).setEnabled(mIsEnabled);
            } catch (RemoteException re) {
                mClients.remove(i);
                count--;
                i--;
            }
        }
    }

    /**
     * This class represents an accessibility service. It stores all per service
     * data required for the service management, provides API for starting/stopping the
     * service and is responsible for adding/removing the service in the data structures
     * for service management. The class also exposes configuration interface that is
     * passed to the service it represents as soon it is bound. It also serves as the
     * connection for the service.
     */
    class Service extends IAccessibilityServiceConnection.Stub implements ServiceConnection {
        int mId = 0;

        IBinder mService;

        IEventListener mServiceInterface;

        int mEventTypes;

        int mFeedbackType;

        Set<String> mPackageNames = new HashSet();

        boolean mIsDefault;

        long mNotificationTimeout;

        boolean mIsActive;

        ComponentName mComponentName;

        Intent mIntent;

        // the events pending events to be dispatched to this service
        final SparseArray<AccessibilityEvent> mPendingEvents =
            new SparseArray<AccessibilityEvent>();

        Service(ComponentName componentName) {
            mId = sIdCounter++;
            mComponentName = componentName;
            mIntent = new Intent().setComponent(mComponentName);
            mIntent.putExtra(Intent.EXTRA_CLIENT_LABEL,
                    com.android.internal.R.string.accessibility_binding_label);
            mIntent.putExtra(Intent.EXTRA_CLIENT_INTENT, PendingIntent.getActivity(
                    mContext, 0, new Intent(Settings.ACTION_ACCESSIBILITY_SETTINGS), 0));
        }

        /**
         * Binds to the accessibility service.
         */
        public void bind() {
            if (mService == null) {
                mContext.bindService(mIntent, this, Context.BIND_AUTO_CREATE);
            }
        }

        /**
         * Unbinds form the accessibility service and removes it from the data
         * structures for service management.
         */
        public void unbind() {
            if (mService != null) {
                mContext.unbindService(this);
            }
        }

        /**
         * Returns if the service is configured i.e. at least event types of interest
         * and feedback type must be set.
         *
         * @return True if the service is configured, false otherwise.
         */
        public boolean isConfigured() {
            return (mEventTypes != 0 && mFeedbackType != 0);
        }

        public void setServiceInfo(AccessibilityServiceInfo info) {
            mCaller.obtainMessageOO(DO_SET_SERVICE_INFO, info, this).sendToTarget();
        }

        public void onServiceConnected(ComponentName componentName, IBinder service) {
            mService = service;
            mServiceInterface = IEventListener.Stub.asInterface(service);

            try {
                mServiceInterface.setConnection(this);
                synchronized (mLock) {
                    if (!mServices.contains(this)) {
                        mServices.add(this);
                        mComponentNameToServiceMap.put(componentName, this);
                    }
                }
            } catch (RemoteException re) {
                Slog.w(LOG_TAG, "Error while setting Controller for service: " + service, re);
            }
        }

        public void onServiceDisconnected(ComponentName componentName) {
            synchronized (mLock) {
                Service service = mComponentNameToServiceMap.remove(componentName);
                mServices.remove(service);
            }
        }
    }
}