Android 10 AMS中拉起系统应用服务以及遇到问题点

需求：需要开机完成拉起系统应用服务
代码路径：
frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java
frameworks/base/services/core/java/com/android/server/am/ActiveServices.java
frameworks/base/core/java/android/content/pm/PackageUserState.java
1、在ActivityManagerService.java文件中finishBooting()文件中启动应用的服务，launchAppWhenBootComplete()该方法中就是被拉起的服务

final void finishBooting() {
		 
        Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "FinishBooting");

        synchronized (this) {
            if (!mBootAnimationComplete) {
                mCallFinishBooting = true;
                return;
            }
            mCallFinishBooting = false;
        }

        ArraySet completedIsas = new ArraySet();
        for (String abi : Build.SUPPORTED_ABIS) {
            ZYGOTE_PROCESS.establishZygoteConnectionForAbi(abi);
            final String instructionSet = VMRuntime.getInstructionSet(abi);
            if (!completedIsas.contains(instructionSet)) {
                try {
                    mInstaller.markBootComplete(VMRuntime.getInstructionSet(abi));
                } catch (InstallerException e) {
                    if (!VMRuntime.didPruneDalvikCache()) {
                        // This is technically not the right filter, as different zygotes may
                        // have made different pruning decisions. But the log is best effort,
                        // anyways.
                        Slog.w(TAG, "Unable to mark boot complete for abi: " + abi + " (" +
                                e.getMessage() +")");
                    }
                }
                completedIsas.add(instructionSet);
            }
        }

        IntentFilter pkgFilter = new IntentFilter();
        pkgFilter.addAction(Intent.ACTION_QUERY_PACKAGE_RESTART);
        pkgFilter.addDataScheme("package");
        mContext.registerReceiver(new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                String[] pkgs = intent.getStringArrayExtra(Intent.EXTRA_PACKAGES);
                if (pkgs != null) {
                    for (String pkg : pkgs) {
                        synchronized (ActivityManagerService.this) {
                            if (forceStopPackageLocked(pkg, -1, false, false, false, false, false,
                                    0, "query restart")) {
                                setResultCode(Activity.RESULT_OK);
                                return;
                            }
                        }
                    }
                }
            }
        }, pkgFilter);

        IntentFilter dumpheapFilter = new IntentFilter();
        dumpheapFilter.addAction(DumpHeapActivity.ACTION_DELETE_DUMPHEAP);
        mContext.registerReceiver(new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                final long delay = intent.getBooleanExtra(
                        DumpHeapActivity.EXTRA_DELAY_DELETE, false) ? 5 * 60 * 1000 : 0;
                mHandler.sendEmptyMessageDelayed(DELETE_DUMPHEAP_MSG, delay);
            }
        }, dumpheapFilter);

        // Inform checkpointing systems of success
        try {
            // This line is needed to CTS test for the correct exception handling
            // See b/138952436 for context
            Slog.i(TAG, "about to commit checkpoint");
            IStorageManager storageManager = PackageHelper.getStorageManager();
            storageManager.commitChanges();
        } catch (Exception e) {
            PowerManager pm = (PowerManager)
                     mContext.getSystemService(Context.POWER_SERVICE);
            pm.reboot("Checkpoint commit failed");
        }

        // Let system services know.
        mSystemServiceManager.startBootPhase(SystemService.PHASE_BOOT_COMPLETED);

        synchronized (this) {
            // Ensure that any processes we had put on hold are now started
            // up.
            final int NP = mProcessesOnHold.size();
            if (NP > 0) {
                ArrayList procs =
                    new ArrayList(mProcessesOnHold);
                for (int ip=0; ip 
遇到问题点：
 在这里拉起服务，会报如下异常
 
2021-10-14 18:02:35.171 18511-18538/system_process W/ActivityManager: Unable to start service Intent { cmp=com.wq.test.Service } U=0: not found
 
分析流程：
 根据日志分析，最后找到该日志是在ActiveServices.java类中retrieveServiceLocked()方法中打印的
 
if (r == null) {
    try {
        int flags = ActivityManagerService.STOCK_PM_FLAGS
                | PackageManager.MATCH_DEBUG_TRIAGED_MISSING;
        if (allowInstant) {
            flags |= PackageManager.MATCH_INSTANT;
        }
        // TODO: come back and remove this assumption to triage all services
        ResolveInfo rInfo = mAm.getPackageManagerInternalLocked().resolveService(service,
                resolvedType, flags, userId, callingUid);
        ServiceInfo sInfo = rInfo != null ? rInfo.serviceInfo : null;
        if (sInfo == null) {
            Slog.w(TAG_SERVICE, "Unable to start service " + service + " U=" + userId +
                  ": not found");
            return null;
        }
        if (instanceName != null
                && (sInfo.flags & ServiceInfo.FLAG_ISOLATED_PROCESS) == 0) {
            throw new IllegalArgumentException("Can't use instance name '" + instanceName
                    + "' with non-isolated service '" + sInfo.name + "'");
        }
        ComponentName className = new ComponentName(
                sInfo.applicationInfo.packageName, sInfo.name);
        ComponentName name = comp != null ? comp : className;
 
原因：
 Android N 引入了一个新的特性 Direct Boot Mode ，设备启动后进入一个新的模式，直到用户解锁后，此模式才会消失。此时若想启动应用，应用必须先向系统注册其组件，然后才能在Direct Boot Mode 模式下运行或访问设备加密存储。 应用通过将组件标记为“加密感知”来注册系统。 若要将您的组件标记为加密感知，请在AndroidManifest.xml中将 android:directBootAware 属性设为 true。
 解决方案
 在AndroidManifest.xml文件中application标签中添加directBootAware属性，我们SystemUI中启动SystemUIService服务也是添加该标签
 
android:directBootAware="true"