Android(安卓)DeepLink原理与应用(2)
3.Android框架层如何实现DeepLink?
上一篇提到Android使用DeepLink跳转有两种方式:Intent跳转、WebView网页跳转。这篇研究一下Android框架如何实现DeepLink。以下Android源代码分析版本为Android7.1。
(1)Intent跳转
这其实是一个Intent filter + start Activity的过程,使用的Intent Catagory是Intent.CATEGORY_BROWSABLE,从这入手。先在Android框架层代码中搜索一下看看哪些地方处理了Intent.CATEGORY_BROWSABLE?发现在处理Intent过滤的工具类中有处理:
frameworks/base/core/java/android/content/IntentFilter.java:
/** * Return if this filter handles HTTP or HTTPS data URIs. * * @return True if the filter handles ACTION_VIEW/CATEGORY_BROWSABLE, * has at least one HTTP or HTTPS data URI pattern defined, and optionally * does not define any non-http/https data URI patterns. * * This will check if if the Intent action is {@link android.content.Intent#ACTION_VIEW} and * the Intent category is {@link android.content.Intent#CATEGORY_BROWSABLE} and the Intent * data scheme is "http" or "https". * * @param onlyWebSchemes When true, requires that the intent filter declare * that it handles *only* http: or https: schemes. This is a requirement for * the intent filter's domain linkage being verifiable. * @hide */ public final boolean handlesWebUris(boolean onlyWebSchemes) { // Require ACTION_VIEW, CATEGORY_BROWSEABLE, and at least one scheme if (!hasAction(Intent.ACTION_VIEW) || !hasCategory(Intent.CATEGORY_BROWSABLE) || mDataSchemes == null || mDataSchemes.size() == 0) { return false; } // Now allow only the schemes "http" and "https" final int N = mDataSchemes.size(); for (int i = 0; i < N; i++) { final String scheme = mDataSchemes.get(i); final boolean isWebScheme = SCHEME_HTTP.equals(scheme) || SCHEME_HTTPS.equals(scheme); if (onlyWebSchemes) { // If we're specifically trying to ensure that there are no non-web schemes // declared in this filter, then if we ever see a non-http/https scheme then // we know it's a failure. if (!isWebScheme) { return false; } } else { // If we see any http/https scheme declaration in this case then the // filter matches what we're looking for. if (isWebScheme) { return true; } } } // We get here if: // 1) onlyWebSchemes and no non-web schemes were found, i.e success; or // 2) !onlyWebSchemes and no http/https schemes were found, i.e. failure. return onlyWebSchemes; }
看到handlesWebUris()处理Intent.CATEGORY_BROWSABLE。需要注意的是,这个方法会根据传入参数的不同调整判断的标准,如果传入true显然只会识别http/https uri。而从Android DeepLink官方文档上看,uri可以定义成非http/https。另一个方法handleAllWebDataURI()可以满足这个限制:
/** * Return if this filter handle all HTTP or HTTPS data URI or not. This is the * core check for whether a given activity qualifies as a "browser". * * @return True if the filter handle all HTTP or HTTPS data URI. False otherwise. * * This will check if: * * - either the Intent category is {@link android.content.Intent#CATEGORY_APP_BROWSER} * - either the Intent action is {@link android.content.Intent#ACTION_VIEW} and * the Intent category is {@link android.content.Intent#CATEGORY_BROWSABLE} and the Intent * data scheme is "http" or "https" and that there is no specific host defined. * * @hide */ public final boolean handleAllWebDataURI() { return hasCategory(Intent.CATEGORY_APP_BROWSER) || (handlesWebUris(false) && countDataAuthorities() == 0); }
继续看handleAllWebDataURI()在什么地方被使用,发现在PackageManagerService的内部类ActivityIntentResolver中,PackageManagerService.ActivityIntentResolver.newResult():
@Override protected ResolveInfo newResult(PackageParser.ActivityIntentInfo info, int match, int userId) { if (!sUserManager.exists(userId)) return null; if (!mSettings.isEnabledAndMatchLPr(info.activity.info, mFlags, userId)) { return null; } final PackageParser.Activity activity = info.activity; PackageSetting ps = (PackageSetting) activity.owner.mExtras; if (ps == null) { return null; } ActivityInfo ai = PackageParser.generateActivityInfo(activity, mFlags, ps.readUserState(userId), userId); if (ai == null) { return null; } final ResolveInfo res = new ResolveInfo(); res.activityInfo = ai; if ((mFlags&PackageManager.GET_RESOLVED_FILTER) != 0) { res.filter = info; } if (info != null) { res.handleAllWebDataURI = info.handleAllWebDataURI(); } res.priority = info.getPriority(); res.preferredOrder = activity.owner.mPreferredOrder; //System.out.println("Result: " + res.activityInfo.className + // " = " + res.priority); res.match = match; res.isDefault = info.hasDefault; res.labelRes = info.labelRes; res.nonLocalizedLabel = info.nonLocalizedLabel; if (userNeedsBadging(userId)) { res.noResourceId = true; } else { res.icon = info.icon; } res.iconResourceId = info.icon; res.system = res.activityInfo.applicationInfo.isSystemApp(); return res; }
其中24行使用了PackageParser.ActivityIntentInfo.handleAllWebDataURI(),PackageParser.ActivityIntentInfo是IntentFilter的子类。
继续追一下newResult()这个方法的使用逻辑。
PackageManagerService.ActivityIntentResolver继承自IntentResolver:
frameworks/base/services/core/java/com/android/server/IntentResolver.java
这是一个抽象类,并且属于Android框架内部类,不属于public api。newResult()这个方法在IntentResolver中定义。
在PackageManagerService中并没有对PackageManagerService.ActivityIntentResolver.newResult()的显式使用,所以这应该是一个模板模式,newResult()在基类的主框架流程中被隐式使用,子类只要根据子集的需求override。
在IntentResolver中调用关系:
queryIntent()/queryIntentFromList() -> buildResolveList() -> newResult()
回到PMS,发现一条重要的调用链:
PackageManagerService.queryIntentActivities() ->
PackageManagerService.ActivityIntentResolver.queryIntent() ->
IntentResolver.queryIntent()
作为对外的接口,PackageManager.queryIntentActivities()的作用是根据给定的Intent参数寻找Activity。
在AMS中,有对于这个方法的调用:
ActivityStackSupervisor.realStartActivityLocked() ->
ActivityManagerService.startSetupActivityLocked() ->
PackageManagerService.queryIntentActivities()
查阅相关资料可知(譬如刘超《深入解析Android5.0系统》),ActivityStackSupervisor.realStartActivityLocked()这个方法是start Activity流程中的一环。由此引发上述分析中的对于Intent.CATEGORY_BROWSABLE的处理。
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