查看resolveActivity方法

    ActivityInfo resolveActivity(Intent intent, String resolvedType, int startFlags,
        ProfilerInfo profilerInfo, int userId) {

    // Collect information about the target of the Intent.
    ActivityInfo aInfo;
    try {
        ResolveInfo rInfo =
            AppGlobals.getPackageManager().resolveIntent(
                    intent, resolvedType,
                    PackageManager.MATCH_DEFAULT_ONLY
                                | ActivityManagerService.STOCK_PM_FLAGS, userId);
        aInfo = rInfo != null ? rInfo.activityInfo : null;
    } catch (RemoteException e) {
        aInfo = null;
    }

    if (aInfo != null) {
        // Store the found target back into the intent, because now that
        // we have it we never want to do this again.  For example, if the
        // user navigates back to this point in the history, we should
        // always restart the exact same activity.
        intent.setComponent(new ComponentName(
                aInfo.applicationInfo.packageName, aInfo.name));

        // Don't debug things in the system process
        if ((startFlags&ActivityManager.START_FLAG_DEBUG) != 0) {
            if (!aInfo.processName.equals("system")) {
                mService.setDebugApp(aInfo.processName, true, false);
            }
        }

        if ((startFlags&ActivityManager.START_FLAG_OPENGL_TRACES) != 0) {
            if (!aInfo.processName.equals("system")) {
                mService.setOpenGlTraceApp(aInfo.applicationInfo, aInfo.processName);
            }
        }

        if (profilerInfo != null) {
            if (!aInfo.processName.equals("system")) {
                mService.setProfileApp(aInfo.applicationInfo, aInfo.processName, profilerInfo);
            }
        }
    }
    return aInfo;
}