PKMS的queryIntentActivities分析

PKMS除了负责Android系统中Package安装、升级、卸载外，还有一个重要的职责，就是对外提供统一的信息查询功能，其中包括查询系统中匹配某Intent的Activity，BroadcastReceiver或Service等。

一、Activity信息的管理

前面在介绍PKMS扫描APK时提到，PKMS将解析得到的Package私有的Activity信息加入到自己的数据结构mActivities中保存。下面是相关代码：

            N = pkg.activities.size();//去除该APK中包含的Activity信息
            r = null;
            for (i=0; i<N; i++) {
                PackageParser.Activity a = pkg.activities.get(i);
                a.info.processName = fixProcessName(pkg.applicationInfo.processName,
                        a.info.processName, pkg.applicationInfo.uid);
                mActivities.addActivity(a, "activity");//加入mActivities保存

先要理解mActivities则个数据类型，mActivities为ActivityIntentResolver类型，是PKMS的成员变量，用于保存系统中所有与Activity相关的信息，它以ComponetName为key，保存PackageParser.Activity对象。由addActivity代码可以看出：

        public final void addActivity(PackageParser.Activity a, String type) {
            final boolean systemApp = isSystemApp(a.info.applicationInfo);
            mActivities.put(a.getComponentName(), a);
            ...
            final int NI = a.intents.size();
            for (int j=0; j<NI; j++) {
                //ActivityIntentInfo存储的就是xml中声明的IntentFilter信息
                PackageParser.ActivityIntentInfo intent = a.intents.get(j);
                if (!systemApp && intent.getPriority() > 0 && "activity".equals(type)) {
                    intent.setPriority(0);//非系统APK的Priority必须为0
                    Log.w(TAG, "Package " + a.info.applicationInfo.packageName + " has activity "
                            + a.className + " with priority > 0, forcing to 0");
                }
                ...
                addFilter(intent);//接下来是分析这个函数，和IntentFilter有关
            }
        }

addFilter代码：

    public void addFilter(F f) {
        ...
        mFilters.add(f);//mFilters保存所有IntentFilter信息
        //除此之外，为了加快匹配工作的速度，还需要分类保存IntentFilter信息
        int numS = register_intent_filter(f, f.schemesIterator(),
                mSchemeToFilter, "      Scheme: ");
        int numT = register_mime_types(f, "      Type: ");
        if (numS == 0 && numT == 0) {
            register_intent_filter(f, f.actionsIterator(),
                    mActionToFilter, "      Action: ");
        }
        if (numT != 0) {
            register_intent_filter(f, f.actionsIterator(),
                    mTypedActionToFilter, "      TypedAction: ");
        }
    }

自此所有Activity的Intent信息都已保存，下面看看Intent匹配查询
二、Intent匹配查询分析

1、客户端查询

客户端通过ApplicationPackageManager输出的queryIntentActivities函数向PKMS发起一起查询请求，代码如下：

        try {
            return mPM.queryIntentActivities(
                intent,
                intent.resolveTypeIfNeeded(mContext.getContentResolver()),
                flags,
                userId);
        }

2、queryIntentActivities分析

    @Override
    public List<ResolveInfo> queryIntentActivities(Intent intent,
            String resolvedType, int flags, int userId) {
        ...
        ComponentName comp = intent.getComponent();
        ...
        if (comp != null) {
            final List<ResolveInfo> list = new ArrayList<ResolveInfo>(1);
            final ActivityInfo ai = getActivityInfo(comp, flags, userId);
            if (ai != null) {
                final ResolveInfo ri = new ResolveInfo();
                ri.activityInfo = ai;
                list.add(ri);
            }
            return list;
        }

        // reader
        synchronized (mPackages) {
            final String pkgName = intent.getPackage();
            if (pkgName == null) {
                List<CrossProfileIntentFilter> matchingFilters =
                        getMatchingCrossProfileIntentFilters(intent, resolvedType, userId);
                // Check for results that need to skip the current profile.
                ResolveInfo resolveInfo  = querySkipCurrentProfileIntents(matchingFilters, intent,
                        resolvedType, flags, userId);
                if (resolveInfo != null) {
                    List<ResolveInfo> result = new ArrayList<ResolveInfo>(1);
                    result.add(resolveInfo);
                    return result;
                }
                // Check for cross profile results.
                resolveInfo = queryCrossProfileIntents(
                        matchingFilters, intent, resolvedType, flags, userId);

                // Check for results in the current profile.
                List<ResolveInfo> result = mActivities.queryIntent(
                        intent, resolvedType, flags, userId);
                if (resolveInfo != null) {
                    result.add(resolveInfo);
                    Collections.sort(result, mResolvePrioritySorter);
                }
                return result;
            }
            final PackageParser.Package pkg = mPackages.get(pkgName);
            if (pkg != null) {
                return mActivities.queryIntentForPackage(intent, resolvedType, flags,
                        pkg.activities, userId);
            }
            return new ArrayList<ResolveInfo>();
        }
    }

上述代码分3种情况：

1、如果Intent指明了Component，则直接查询该Component对应的ActivityInfo。

2、如果指明了Package名，则从该Package包含的Activities中进行匹配查询。

3、若没有上述限定，则在全系统范围内进行匹配查询，就是queryIntent的工作。

 

    public List<R> queryIntent(Intent intent, String resolvedType, boolean defaultOnly,
            int userId) {
        String scheme = intent.getScheme();

        ArrayList<R> finalList = new ArrayList<R>();
        ...
        F[] firstTypeCut = null;
        F[] secondTypeCut = null;
        F[] thirdTypeCut = null;
        F[] schemeCut = null;

        // If the intent includes a MIME type, then we want to collect all of
        // the filters that match that MIME type.
        if (resolvedType != null) {
            int slashpos = resolvedType.indexOf('/');
            if (slashpos > 0) {
                final String baseType = resolvedType.substring(0, slashpos);
                if (!baseType.equals("*")) {
                    if (resolvedType.length() != slashpos+2
                            || resolvedType.charAt(slashpos+1) != '*') {
                        // Not a wild card, so we can just look for all filters that
                        // completely match or wildcards whose base type matches.
                        firstTypeCut = mTypeToFilter.get(resolvedType);
                        if (debug) Slog.v(TAG, "First type cut: " + Arrays.toString(firstTypeCut));
                        secondTypeCut = mWildTypeToFilter.get(baseType);
                        if (debug) Slog.v(TAG, "Second type cut: "
                                + Arrays.toString(secondTypeCut));
                    } 
                    ...
            }
        }

        // If the intent includes a data URI, then we want to collect all of
        // the filters that match its scheme (we will further refine matches
        // on the authority and path by directly matching each resulting filter).
        if (scheme != null) {
            schemeCut = mSchemeToFilter.get(scheme);
            if (debug) Slog.v(TAG, "Scheme list: " + Arrays.toString(schemeCut));
        }

        // If the intent does not specify any data -- either a MIME type or
        // a URI -- then we will only be looking for matches against empty
        // data.
        if (resolvedType == null && scheme == null && intent.getAction() != null) {
            firstTypeCut = mActionToFilter.get(intent.getAction());
            if (debug) Slog.v(TAG, "Action list: " + Arrays.toString(firstTypeCut));
        }
        //FastImmutableArraySet是战役中特殊的数据结构，用于保存该Intent中携带的category相关信息
        FastImmutableArraySet<String> categories = getFastIntentCategories(intent);
        if (firstTypeCut != null) {
            buildResolveList(intent, categories, debug, defaultOnly,
                    resolvedType, scheme, firstTypeCut, finalList, userId);
        }
        if (secondTypeCut != null) {
            buildResolveList(intent, categories, debug, defaultOnly,
                    resolvedType, scheme, secondTypeCut, finalList, userId);
        }
        if (thirdTypeCut != null) {
            buildResolveList(intent, categories, debug, defaultOnly,
                    resolvedType, scheme, thirdTypeCut, finalList, userId);
        }
        if (schemeCut != null) {
            buildResolveList(intent, categories, debug, defaultOnly,
                    resolvedType, scheme, schemeCut, finalList, userId);
        }
        sortResults(finalList);//将匹配结果按priority大小排序
        ...
        return finalList;
    }

 queryIntentActivities功能简单粗暴，数据结构较多，目的性强，不难分析