Android example source code file (RegisteredServicesCache.java)

This example Android source code file (RegisteredServicesCache.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

android, arraylist, broadcastreceiver, componentname, content, file, intentfilter, io, override, packagemanager, registeredservicescache, registeredservicescachelistener, serviceinfo, string, unable, util, utilities, utils, v, xmlpullparserexception

The RegisteredServicesCache.java Android example source code

/*
 * Copyright (C) 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 android.content.pm;

import android.content.Context;
import android.content.BroadcastReceiver;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.ComponentName;
import android.content.pm.PackageManager.NameNotFoundException;
import android.content.res.Resources;
import android.content.res.XmlResourceParser;
import android.os.Environment;
import android.os.Handler;
import android.util.Log;
import android.util.AttributeSet;
import android.util.Xml;

import java.util.Map;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.ArrayList;
import java.util.concurrent.atomic.AtomicReference;
import java.io.File;
import java.io.FileOutputStream;
import java.io.FileDescriptor;
import java.io.PrintWriter;
import java.io.IOException;
import java.io.FileInputStream;

import com.android.internal.os.AtomicFile;
import com.android.internal.util.FastXmlSerializer;

import com.google.android.collect.Maps;
import com.google.android.collect.Lists;

import org.xmlpull.v1.XmlPullParserException;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlSerializer;

/**
 * A cache of registered services. This cache
 * is built by interrogating the {@link PackageManager} and is updated as packages are added,
 * removed and changed. The services are referred to by type V and
 * are made available via the {@link #getServiceInfo} method.
 * @hide
 */
public abstract class RegisteredServicesCache<V> {
    private static final String TAG = "PackageManager";

    public final Context mContext;
    private final String mInterfaceName;
    private final String mMetaDataName;
    private final String mAttributesName;
    private final XmlSerializerAndParser<V> mSerializerAndParser;
    private final AtomicReference<BroadcastReceiver> mReceiver;

    private final Object mServicesLock = new Object();
    // synchronized on mServicesLock
    private HashMap<V, Integer> mPersistentServices;
    // synchronized on mServicesLock
    private Map<V, ServiceInfo mServices;
    // synchronized on mServicesLock
    private boolean mPersistentServicesFileDidNotExist;

    /**
     * This file contains the list of known services. We would like to maintain this forever
     * so we store it as an XML file.
     */
    private final AtomicFile mPersistentServicesFile;

    // the listener and handler are synchronized on "this" and must be updated together
    private RegisteredServicesCacheListener<V> mListener;
    private Handler mHandler;

    public RegisteredServicesCache(Context context, String interfaceName, String metaDataName,
            String attributeName, XmlSerializerAndParser<V> serializerAndParser) {
        mContext = context;
        mInterfaceName = interfaceName;
        mMetaDataName = metaDataName;
        mAttributesName = attributeName;
        mSerializerAndParser = serializerAndParser;

        File dataDir = Environment.getDataDirectory();
        File systemDir = new File(dataDir, "system");
        File syncDir = new File(systemDir, "registered_services");
        mPersistentServicesFile = new AtomicFile(new File(syncDir, interfaceName + ".xml"));

        generateServicesMap();

        final BroadcastReceiver receiver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context1, Intent intent) {
                generateServicesMap();
            }
        };
        mReceiver = new AtomicReference<BroadcastReceiver>(receiver);
        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction(Intent.ACTION_PACKAGE_ADDED);
        intentFilter.addAction(Intent.ACTION_PACKAGE_CHANGED);
        intentFilter.addAction(Intent.ACTION_PACKAGE_REMOVED);
        intentFilter.addDataScheme("package");
        mContext.registerReceiver(receiver, intentFilter);
        // Register for events related to sdcard installation.
        IntentFilter sdFilter = new IntentFilter();
        sdFilter.addAction(Intent.ACTION_EXTERNAL_APPLICATIONS_AVAILABLE);
        sdFilter.addAction(Intent.ACTION_EXTERNAL_APPLICATIONS_UNAVAILABLE);
        mContext.registerReceiver(receiver, sdFilter);
    }

    public void dump(FileDescriptor fd, PrintWriter fout, String[] args) {
        Map<V, ServiceInfo services;
        synchronized (mServicesLock) {
            services = mServices;
        }
        fout.println("RegisteredServicesCache: " + services.size() + " services");
        for (ServiceInfo info : services.values()) {
            fout.println("  " + info);
        }
    }

    public RegisteredServicesCacheListener<V> getListener() {
        synchronized (this) {
            return mListener;
        }
    }

    public void setListener(RegisteredServicesCacheListener<V> listener, Handler handler) {
        if (handler == null) {
            handler = new Handler(mContext.getMainLooper());
        }
        synchronized (this) {
            mHandler = handler;
            mListener = listener;
        }
    }

    private void notifyListener(final V type, final boolean removed) {
        if (Log.isLoggable(TAG, Log.VERBOSE)) {
            Log.d(TAG, "notifyListener: " + type + " is " + (removed ? "removed" : "added"));
        }
        RegisteredServicesCacheListener<V> listener;
        Handler handler; 
        synchronized (this) {
            listener = mListener;
            handler = mHandler;
        }
        if (listener == null) {
            return;
        }
        
        final RegisteredServicesCacheListener<V> listener2 = listener;
        handler.post(new Runnable() {
            public void run() {
                listener2.onServiceChanged(type, removed);
            }
        });
    }

    /**
     * Value type that describes a Service. The information within can be used
     * to bind to the service.
     */
    public static class ServiceInfo<V> {
        public final V type;
        public final ComponentName componentName;
        public final int uid;

        private ServiceInfo(V type, ComponentName componentName, int uid) {
            this.type = type;
            this.componentName = componentName;
            this.uid = uid;
        }

        @Override
        public String toString() {
            return "ServiceInfo: " + type + ", " + componentName + ", uid " + uid;
        }
    }

    /**
     * Accessor for the registered authenticators.
     * @param type the account type of the authenticator
     * @return the AuthenticatorInfo that matches the account type or null if none is present
     */
    public ServiceInfo<V> getServiceInfo(V type) {
        synchronized (mServicesLock) {
            return mServices.get(type);
        }
    }

    /**
     * @return a collection of {@link RegisteredServicesCache.ServiceInfo} objects for all
     * registered authenticators.
     */
    public Collection<ServiceInfo getAllServices() {
        synchronized (mServicesLock) {
            return Collections.unmodifiableCollection(mServices.values());
        }
    }

    /**
     * Stops the monitoring of package additions, removals and changes.
     */
    public void close() {
        final BroadcastReceiver receiver = mReceiver.getAndSet(null);
        if (receiver != null) {
            mContext.unregisterReceiver(receiver);
        }
    }

    @Override
    protected void finalize() throws Throwable {
        if (mReceiver.get() != null) {
            Log.e(TAG, "RegisteredServicesCache finalized without being closed");
        }
        close();
        super.finalize();
    }

    private boolean inSystemImage(int callerUid) {
        String[] packages = mContext.getPackageManager().getPackagesForUid(callerUid);
        for (String name : packages) {
            try {
                PackageInfo packageInfo =
                        mContext.getPackageManager().getPackageInfo(name, 0 /* flags */);
                if ((packageInfo.applicationInfo.flags & ApplicationInfo.FLAG_SYSTEM) != 0) {
                    return true;
                }
            } catch (PackageManager.NameNotFoundException e) {
                return false;
            }
        }
        return false;
    }

    void generateServicesMap() {
        PackageManager pm = mContext.getPackageManager();
        ArrayList<ServiceInfo serviceInfos = new ArrayList>();
        List<ResolveInfo> resolveInfos = pm.queryIntentServices(new Intent(mInterfaceName),
                PackageManager.GET_META_DATA);
        for (ResolveInfo resolveInfo : resolveInfos) {
            try {
                ServiceInfo<V> info = parseServiceInfo(resolveInfo);
                if (info == null) {
                    Log.w(TAG, "Unable to load service info " + resolveInfo.toString());
                    continue;
                }
                serviceInfos.add(info);
            } catch (XmlPullParserException e) {
                Log.w(TAG, "Unable to load service info " + resolveInfo.toString(), e);
            } catch (IOException e) {
                Log.w(TAG, "Unable to load service info " + resolveInfo.toString(), e);
            }
        }

        synchronized (mServicesLock) {
            if (Log.isLoggable(TAG, Log.VERBOSE)) {
                Log.d(TAG, "generateServicesMap: " + mInterfaceName);
            }
            if (mPersistentServices == null) {
                readPersistentServicesLocked();
            }
            mServices = Maps.newHashMap();
            boolean changed = false;
            if (Log.isLoggable(TAG, Log.VERBOSE)) {
                Log.d(TAG, "found " + serviceInfos.size() + " services");
            }
            for (ServiceInfo<V> info : serviceInfos) {
                // four cases:
                // - doesn't exist yet
                //   - add, notify user that it was added
                // - exists and the UID is the same
                //   - replace, don't notify user
                // - exists, the UID is different, and the new one is not a system package
                //   - ignore
                // - exists, the UID is different, and the new one is a system package
                //   - add, notify user that it was added
                Integer previousUid = mPersistentServices.get(info.type);
                if (previousUid == null) {
                    if (Log.isLoggable(TAG, Log.VERBOSE)) {
                        Log.d(TAG, "encountered new type: " + info);
                    }
                    changed = true;
                    mServices.put(info.type, info);
                    mPersistentServices.put(info.type, info.uid);
                    if (!mPersistentServicesFileDidNotExist) {
                        notifyListener(info.type, false /* removed */);
                    }
                } else if (previousUid == info.uid) {
                    if (Log.isLoggable(TAG, Log.VERBOSE)) {
                        Log.d(TAG, "encountered existing type with the same uid: " + info);
                    }
                    mServices.put(info.type, info);
                } else if (inSystemImage(info.uid)
                        || !containsTypeAndUid(serviceInfos, info.type, previousUid)) {
                    if (Log.isLoggable(TAG, Log.VERBOSE)) {
                        if (inSystemImage(info.uid)) {
                            Log.d(TAG, "encountered existing type with a new uid but from"
                                    + " the system: " + info);
                        } else {
                            Log.d(TAG, "encountered existing type with a new uid but existing was"
                                    + " removed: " + info);
                        }
                    }
                    changed = true;
                    mServices.put(info.type, info);
                    mPersistentServices.put(info.type, info.uid);
                    notifyListener(info.type, false /* removed */);
                } else {
                    // ignore
                    if (Log.isLoggable(TAG, Log.VERBOSE)) {
                        Log.d(TAG, "encountered existing type with a new uid, ignoring: " + info);
                    }
                }
            }

            ArrayList<V> toBeRemoved = Lists.newArrayList();
            for (V v1 : mPersistentServices.keySet()) {
                if (!containsType(serviceInfos, v1)) {
                    toBeRemoved.add(v1);
                }
            }
            for (V v1 : toBeRemoved) {
                mPersistentServices.remove(v1);
                changed = true;
                notifyListener(v1, true /* removed */);
            }
            if (changed) {
                if (Log.isLoggable(TAG, Log.VERBOSE)) {
                    Log.d(TAG, "writing updated list of persistent services");
                }
                writePersistentServicesLocked();
            } else {
                if (Log.isLoggable(TAG, Log.VERBOSE)) {
                    Log.d(TAG, "persistent services did not change, so not writing anything");
                }
            }
            mPersistentServicesFileDidNotExist = false;
        }
    }

    private boolean containsType(ArrayList<ServiceInfo serviceInfos, V type) {
        for (int i = 0, N = serviceInfos.size(); i < N; i++) {
            if (serviceInfos.get(i).type.equals(type)) {
                return true;
            }
        }

        return false;
    }

    private boolean containsTypeAndUid(ArrayList<ServiceInfo serviceInfos, V type, int uid) {
        for (int i = 0, N = serviceInfos.size(); i < N; i++) {
            final ServiceInfo<V> serviceInfo = serviceInfos.get(i);
            if (serviceInfo.type.equals(type) && serviceInfo.uid == uid) {
                return true;
            }
        }

        return false;
    }

    private ServiceInfo<V> parseServiceInfo(ResolveInfo service)
            throws XmlPullParserException, IOException {
        android.content.pm.ServiceInfo si = service.serviceInfo;
        ComponentName componentName = new ComponentName(si.packageName, si.name);

        PackageManager pm = mContext.getPackageManager();

        XmlResourceParser parser = null;
        try {
            parser = si.loadXmlMetaData(pm, mMetaDataName);
            if (parser == null) {
                throw new XmlPullParserException("No " + mMetaDataName + " meta-data");
            }

            AttributeSet attrs = Xml.asAttributeSet(parser);

            int type;
            while ((type=parser.next()) != XmlPullParser.END_DOCUMENT
                    && type != XmlPullParser.START_TAG) {
            }

            String nodeName = parser.getName();
            if (!mAttributesName.equals(nodeName)) {
                throw new XmlPullParserException(
                        "Meta-data does not start with " + mAttributesName +  " tag");
            }

            V v = parseServiceAttributes(pm.getResourcesForApplication(si.applicationInfo),
                    si.packageName, attrs);
            if (v == null) {
                return null;
            }
            final android.content.pm.ServiceInfo serviceInfo = service.serviceInfo;
            final ApplicationInfo applicationInfo = serviceInfo.applicationInfo;
            final int uid = applicationInfo.uid;
            return new ServiceInfo<V>(v, componentName, uid);
        } catch (NameNotFoundException e) {
            throw new XmlPullParserException(
                    "Unable to load resources for pacakge " + si.packageName);
        } finally {
            if (parser != null) parser.close();
        }
    }

    /**
     * Read all sync status back in to the initial engine state.
     */
    private void readPersistentServicesLocked() {
        mPersistentServices = Maps.newHashMap();
        if (mSerializerAndParser == null) {
            return;
        }
        FileInputStream fis = null;
        try {
            mPersistentServicesFileDidNotExist = !mPersistentServicesFile.getBaseFile().exists();
            if (mPersistentServicesFileDidNotExist) {
                return;
            }
            fis = mPersistentServicesFile.openRead();
            XmlPullParser parser = Xml.newPullParser();
            parser.setInput(fis, null);
            int eventType = parser.getEventType();
            while (eventType != XmlPullParser.START_TAG) {
                eventType = parser.next();
            }
            String tagName = parser.getName();
            if ("services".equals(tagName)) {
                eventType = parser.next();
                do {
                    if (eventType == XmlPullParser.START_TAG && parser.getDepth() == 2) {
                        tagName = parser.getName();
                        if ("service".equals(tagName)) {
                            V service = mSerializerAndParser.createFromXml(parser);
                            if (service == null) {
                                break;
                            }
                            String uidString = parser.getAttributeValue(null, "uid");
                            int uid = Integer.parseInt(uidString);
                            mPersistentServices.put(service, uid);
                        }
                    }
                    eventType = parser.next();
                } while (eventType != XmlPullParser.END_DOCUMENT);
            }
        } catch (Exception e) {
            Log.w(TAG, "Error reading persistent services, starting from scratch", e);
        } finally {
            if (fis != null) {
                try {
                    fis.close();
                } catch (java.io.IOException e1) {
                }
            }
        }
    }

    /**
     * Write all sync status to the sync status file.
     */
    private void writePersistentServicesLocked() {
        if (mSerializerAndParser == null) {
            return;
        }
        FileOutputStream fos = null;
        try {
            fos = mPersistentServicesFile.startWrite();
            XmlSerializer out = new FastXmlSerializer();
            out.setOutput(fos, "utf-8");
            out.startDocument(null, true);
            out.setFeature("http://xmlpull.org/v1/doc/features.html#indent-output", true);
            out.startTag(null, "services");
            for (Map.Entry<V, Integer> service : mPersistentServices.entrySet()) {
                out.startTag(null, "service");
                out.attribute(null, "uid", Integer.toString(service.getValue()));
                mSerializerAndParser.writeAsXml(service.getKey(), out);
                out.endTag(null, "service");
            }
            out.endTag(null, "services");
            out.endDocument();
            mPersistentServicesFile.finishWrite(fos);
        } catch (java.io.IOException e1) {
            Log.w(TAG, "Error writing accounts", e1);
            if (fos != null) {
                mPersistentServicesFile.failWrite(fos);
            }
        }
    }

    public abstract V parseServiceAttributes(Resources res,
            String packageName, AttributeSet attrs);
}