Android恢复出厂设置流程分析【Android源码解析十】

最近看恢复出厂的一个问题，以前也查过这方面的流程，所以这里整理一些AP+framework层的流程；

在setting-->备份与重置--->恢复出厂设置--->重置手机--->清除全部内容--->手机关机--->开机--->进行恢复出厂的操作--->开机流程；

Step 1：前面找settings中的布局我就省略了，这部分相对简单一些，直接到清除全部内容这个按钮的操作，

对应的java类是setting中的MasterClearConfirm.java这个类，

private Button.OnClickListener mFinalClickListener = new Button.OnClickListener() {

        public void onClick(View v) {
            if (Utils.isMonkeyRunning()) {
                return;
            }

            if (mEraseSdCard) {
                Intent intent = new Intent(ExternalStorageFormatter.FORMAT_AND_FACTORY_RESET);
                intent.setComponent(ExternalStorageFormatter.COMPONENT_NAME);
                getActivity().startService(intent);
            } else {
                getActivity().sendBroadcast(new Intent("android.intent.action.MASTER_CLEAR"));
                // Intent handling is asynchronous -- assume it will happen soon.
            }
        }
    };

通过上述的代码，可以看出，实际上点击清除全部内容的时候，如果前面勾选上格式哈SD卡，就会执行mEraseSdCard为true里面的逻辑，如果没有勾选，就执行mEraseSdCard=false的逻辑，其实就是发送一个广播，

“android.intent.action.MASTER_CLEAR”

Step 2：这个广播接受的地方，参见AndroidManifest.xml中的代码，如下：

<receiver android:name="com.android.server.MasterClearReceiver"
            android:permission="android.permission.MASTER_CLEAR"
            android:priority="100" >
            <intent-filter>
                <!-- For Checkin, Settings, etc.: action=MASTER_CLEAR -->
                <action android:name="android.intent.action.MASTER_CLEAR" />

                <!-- MCS always uses REMOTE_INTENT: category=MASTER_CLEAR -->
                <action android:name="com.google.android.c2dm.intent.RECEIVE" />
                <category android:name="android.intent.category.MASTER_CLEAR" />
            </intent-filter>
        </receiver>

找这个MasterClearReceiver.java这个receiver，下面来看看这个onReceiver()里面做了什么操作：

public void onReceive(final Context context, final Intent intent) {
        if (intent.getAction().equals(Intent.ACTION_REMOTE_INTENT)) {
            if (!"google.com".equals(intent.getStringExtra("from"))) {
                Slog.w(TAG, "Ignoring master clear request -- not from trusted server.");
                return;
            }
        }

        Slog.w(TAG, "!!! FACTORY RESET !!!");
        // The reboot call is blocking, so we need to do it on another thread.
        Thread thr = new Thread("Reboot") {
            @Override
            public void run() {
                try {
                    RecoverySystem.rebootWipeUserData(context);
                    Log.wtf(TAG, "Still running after master clear?!");
                } catch (IOException e) {
                    Slog.e(TAG, "Can't perform master clear/factory reset", e);
                }
            }
        };
        thr.start();
    }

这个里面主要的操作是：RecoverySystem.rebootWipeUserData(context);准备做重启的动作，告诉手机要清除userData的数据；

Step 3：接着来看看RecoverySystem.rebootWipeUserData（）这个方法做了哪些操作：

public static void rebootWipeUserData(Context context) throws IOException {
        final ConditionVariable condition = new ConditionVariable();

        Intent intent = new Intent("android.intent.action.MASTER_CLEAR_NOTIFICATION");
        context.sendOrderedBroadcastAsUser(intent, UserHandle.OWNER,
                android.Manifest.permission.MASTER_CLEAR,
                new BroadcastReceiver() {
                    @Override
                    public void onReceive(Context context, Intent intent) {
                        condition.open();
                    }
                }, null, 0, null, null);

        // Block until the ordered broadcast has completed.
        condition.block();

        bootCommand(context, "--wipe_data\n--locale=" + Locale.getDefault().toString());
    }

这个里面的广播可以先忽略不计，重点来看看bootCommand（）这个方法，注意这个参数“--wipe_data\n--locale=”

private static void bootCommand(Context context, String arg) throws IOException {
        RECOVERY_DIR.mkdirs();  // In case we need it
        COMMAND_FILE.delete();  // In case it's not writable
        LOG_FILE.delete();

        FileWriter command = new FileWriter(COMMAND_FILE);
        try {
            command.write(arg);
            command.write("\n");
        } finally {
            command.close();
        }

        // Having written the command file, go ahead and reboot
        PowerManager pm = (PowerManager) context.getSystemService(Context.POWER_SERVICE);
        pm.reboot("recovery");

        throw new IOException("Reboot failed (no permissions?)");
    }

这个方法的操作大致是“写节点/cache/recovery/command”，把传递过来的字符串写进去；然后调用PowerManager进行重启操作，reboot（）；

Step 4：接着我们来看看PowerManager的reboot方法做了哪些操作：

  public void reboot(String reason) {
        try {
            mService.reboot(false, reason, true);
        } catch (RemoteException e) {
        }
    }

这个调用到了PowerManagerService.java这个类的reboot方法中了：

@Override // Binder call
    public void reboot(boolean confirm, String reason, boolean wait) {
        mContext.enforceCallingOrSelfPermission(android.Manifest.permission.REBOOT, null);

        final long ident = Binder.clearCallingIdentity();
        try {
            shutdownOrRebootInternal(false, confirm, reason, wait);
        } finally {
            Binder.restoreCallingIdentity(ident);
        }
    }

重点来看看shutdownOrRebootInternal（）这个方法，

private void shutdownOrRebootInternal(final boolean shutdown, final boolean confirm,
            final String reason, boolean wait) {
        if (mHandler == null || !mSystemReady) {
            throw new IllegalStateException("Too early to call shutdown() or reboot()");
        }

        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                synchronized (this) {
                    if (shutdown) {
                        ShutdownThread.shutdown(mContext, confirm);
                    } else {
                        ShutdownThread.reboot(mContext, reason, confirm);
                    }
                }
            }
        };

        // ShutdownThread must run on a looper capable of displaying the UI.
        Message msg = Message.obtain(mHandler, runnable);
        msg.setAsynchronous(true);
        mHandler.sendMessage(msg);

        // PowerManager.reboot() is documented not to return so just wait for the inevitable.
        if (wait) {
            synchronized (runnable) {
                while (true) {
                    try {
                        runnable.wait();
                    } catch (InterruptedException e) {
                    }
                }
            }
        }
    }

由于传递过来的shutdown为false，所以执行ShutdownThread.reboot(mContext, reason, confirm);reason：recevory

下面调用到ShutdownThread

Step 5：这个追踪ShutdownThread.reboot()这个方法，这就有点像破案电影，一点一点查找罪犯的难点；

来窥视一下这个类：

 public static void reboot(final Context context, String reason, boolean confirm) {
        mReboot = true;
        mRebootSafeMode = false;
        mRebootReason = reason;
        Log.d(TAG, "reboot");
        shutdownInner(context, confirm);
    }

这个里面做的操作就是给这个变量mRebootReason复制“recevory”，重点调用shutdownInner（）这个方法；

static void shutdownInner(final Context context, boolean confirm) {
        // ensure that only one thread is trying to power down.
        // any additional calls are just returned
        synchronized (sIsStartedGuard) {
            if (sIsStarted) {
                Log.d(TAG, "Request to shutdown already running, returning.");
                return;
            }
        }

        Log.d(TAG, "Notifying thread to start radio shutdown");
        bConfirmForAnimation = confirm;
        final int longPressBehavior = context.getResources().getInteger(
                com.android.internal.R.integer.config_longPressOnPowerBehavior);
        final int resourceId = mRebootSafeMode
            ? com.android.internal.R.string.reboot_safemode_confirm
            : (longPressBehavior == 2
                    ? com.android.internal.R.string.shutdown_confirm_question
                    : com.android.internal.R.string.shutdown_confirm);

        Log.d(TAG, "Notifying thread to start shutdown longPressBehavior=" + longPressBehavior);

        if (confirm) {
            final CloseDialogReceiver closer = new CloseDialogReceiver(context);
            if (sConfirmDialog != null) {
                sConfirmDialog.dismiss();
            }
            if (sConfirmDialog == null) {
                Log.d(TAG, "PowerOff dialog doesn't exist. Create it first");
                sConfirmDialog = new AlertDialog.Builder(context)
                    .setTitle(mRebootSafeMode
                            ? com.android.internal.R.string.reboot_safemode_title
                            : com.android.internal.R.string.power_off)
                    .setMessage(resourceId)
                    .setPositiveButton(com.android.internal.R.string.yes, new DialogInterface.OnClickListener() {
                            public void onClick(DialogInterface dialog, int which) {
                            beginShutdownSequence(context);
                            if (sConfirmDialog != null) {
                            sConfirmDialog = null;
                            }
                            }
                            })
                .setNegativeButton(com.android.internal.R.string.no, new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int which) {
                        synchronized (sIsStartedGuard) {
                        sIsStarted = false;
                        }
                        if (sConfirmDialog != null) {
                        sConfirmDialog = null;
                        }
                        }
                        })
                .create();
                sConfirmDialog.setCancelable(false);//blocking back key
                sConfirmDialog.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD_DIALOG);
                /*if (!context.getResources().getBoolean(
                  com.android.internal.R.bool.config_sf_slowBlur)) {
                  sConfirmDialog.getWindow().addFlags(WindowManager.LayoutParams.FLAG_BLUR_BEHIND);
                  }*/
                /* To fix video+UI+blur flick issue */
                sConfirmDialog.getWindow().addFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND);
            }

            closer.dialog = sConfirmDialog;
            sConfirmDialog.setOnDismissListener(closer);

            if (!sConfirmDialog.isShowing()) {
                sConfirmDialog.show();
            }
        } else {
            beginShutdownSequence(context);
        }
    }

看beginShutdownSequence（）这个方法吧，重点调用到这个方法里面去了，来瞅瞅这个方法：

private static void beginShutdownSequence(Context context) {
        synchronized (sIsStartedGuard) {
            if (sIsStarted) {
                Log.e(TAG, "ShutdownThread is already running, returning.");		
                return;
            }
            sIsStarted = true;
        }

        // start the thread that initiates shutdown
        sInstance.mContext = context;
        sInstance.mPowerManager = (PowerManager)context.getSystemService(Context.POWER_SERVICE);
        sInstance.mHandler = new Handler() {
        };    

        bPlayaudio = true;
        if (!bConfirmForAnimation) {
            if (!sInstance.mPowerManager.isScreenOn()) {
                bPlayaudio = false;
            }
        }

        // throw up an indeterminate system dialog to indicate radio is
        // shutting down.
        beginAnimationTime = 0;
        boolean mShutOffAnimation = false;

        try {
            if (mIBootAnim == null) {
                mIBootAnim = MediatekClassFactory.createInstance(IBootAnimExt.class);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

        int screenTurnOffTime = mIBootAnim.getScreenTurnOffTime();
        mShutOffAnimation = mIBootAnim.isCustBootAnim();
        Log.e(TAG, "mIBootAnim get screenTurnOffTime : " + screenTurnOffTime);

        String cust = SystemProperties.get("ro.operator.optr");

        if (cust != null) {
            if (cust.equals("CUST")) {
                mShutOffAnimation = true;
            }
        }

        synchronized (mEnableAnimatingSync) {

            if(!mEnableAnimating) {
//                sInstance.mPowerManager.setBacklightBrightness(PowerManager.BRIGHTNESS_DIM);
            } else {
                if (mShutOffAnimation) {
                    Log.e(TAG, "mIBootAnim.isCustBootAnim() is true");
                    bootanimCust();
                } else {
                    pd = new ProgressDialog(context);
                    pd.setTitle(context.getText(com.android.internal.R.string.power_off));
                    pd.setMessage(context.getText(com.android.internal.R.string.shutdown_progress));
                    pd.setIndeterminate(true);
                    pd.setCancelable(false);
                    pd.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD_DIALOG);
                    /* To fix video+UI+blur flick issue */
                    pd.getWindow().addFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND);
                    pd.show();
                }
                sInstance.mHandler.postDelayed(mDelayDim, screenTurnOffTime ); 
            }
        }

        // make sure we never fall asleep again
        sInstance.mCpuWakeLock = null;
        try {
            sInstance.mCpuWakeLock = sInstance.mPowerManager.newWakeLock(
                    。。。 。。。
}

这段代码有句话会影响关机动画播放不完

“sInstance.mHandler.postDelayed(mDelayDim, screenTurnOffTime );”

解决办法

（1）“可以把这个screenTurnOffTime时间乘以2，这个时间看log是5000毫秒，就是5秒，乘以2就是10秒，大概就能播放完全关机动画了。”

（2）把这句话注释掉，但是有可能会引起问题，导致恢复出厂设置的时候没有进行恢复出厂的操作。目前正在追踪此问题；

这段代码中还有影响关机动画是否走客制化的关机动画，如果ro.operator.optr这个属性配置的是CUST，则会走客制化的关机动画，否则走系统默认的关机动画；

String cust = SystemProperties.get("ro.operator.optr");


        if (cust != null) {
            if (cust.equals("CUST")) {
                mShutOffAnimation = true;
            }
        }

然后重点看sInstance.start();这个方法，就走到了run（）方法里满了；

Step 6： 来看看ShutDownThread.java这个类的run（）方法；

public void run() {
        checkShutdownFlow();
        while (mShutdownFlow == IPO_SHUTDOWN_FLOW) {
            stMgr.saveStates(mContext);
            stMgr.enterShutdown(mContext);
            running();
        } 
        if (mShutdownFlow != IPO_SHUTDOWN_FLOW) {
            stMgr.enterShutdown(mContext);
            running();
        }
    }

重点看running（）这个方法：

下面这个方法比较长，来分析一下：

 public void running() {
        if(sPreShutdownApi != null){
            try {
                sPreShutdownApi.onPowerOff();
            } catch (RemoteException e) {
                Log.e(TAG, "onPowerOff exception" + e.getMessage());
            }
        }else{
            Log.w(TAG, "sPreShutdownApi is null");
        }

        command = SystemProperties.get("sys.ipo.pwrdncap");

        BroadcastReceiver br = new BroadcastReceiver() {
            @Override public void onReceive(Context context, Intent intent) {
                // We don't allow apps to cancel this, so ignore the result.
                actionDone();
            }
        };

        /*
         * Write a system property in case the system_server reboots before we
         * get to the actual hardware restart. If that happens, we'll retry at
         * the beginning of the SystemServer startup.
         */
        {
            String reason = (mReboot ? "1" : "0") + (mRebootReason != null ? mRebootReason : "");
            SystemProperties.set(SHUTDOWN_ACTION_PROPERTY, reason);
        }

        /*
         * If we are rebooting into safe mode, write a system property
         * indicating so.
         */
        if (mRebootSafeMode) {
            SystemProperties.set(REBOOT_SAFEMODE_PROPERTY, "1");
        }

        Log.i(TAG, "Sending shutdown broadcast...");

        // First send the high-level shut down broadcast.
        mActionDone = false;
        /// M: 2012-05-20 ALPS00286063 @{
        mContext.sendBroadcast(new Intent("android.intent.action.ACTION_PRE_SHUTDOWN"));
        /// @} 2012-05-20
        mContext.sendOrderedBroadcastAsUser((new Intent()).setAction(Intent.ACTION_SHUTDOWN).putExtra("_mode", mShutdownFlow),
                UserHandle.ALL, null, br, mHandler, 0, null, null);
        
        final long endTime = SystemClock.elapsedRealtime() + MAX_BROADCAST_TIME;
        synchronized (mActionDoneSync) {
            while (!mActionDone) {
                long delay = endTime - SystemClock.elapsedRealtime();
                if (delay <= 0) {
                    Log.w(TAG, "Shutdown broadcast ACTION_SHUTDOWN timed out");
                    if (mShutdownFlow == IPO_SHUTDOWN_FLOW) {
                        Log.d(TAG, "change shutdown flow from ipo to normal: ACTION_SHUTDOWN timeout");
                        mShutdownFlow = NORMAL_SHUTDOWN_FLOW;
                    }
                    break;
                }
                try {
                    mActionDoneSync.wait(delay);
                } catch (InterruptedException e) {
                }
            }
        }

        // Also send ACTION_SHUTDOWN_IPO in IPO shut down flow
        if (mShutdownFlow == IPO_SHUTDOWN_FLOW) {
            mActionDone = false;
            mContext.sendOrderedBroadcast(new Intent("android.intent.action.ACTION_SHUTDOWN_IPO"), null,
                    br, mHandler, 0, null, null);
            final long endTimeIPO = SystemClock.elapsedRealtime() + MAX_BROADCAST_TIME;
            synchronized (mActionDoneSync) {
                while (!mActionDone) {
                    long delay = endTimeIPO - SystemClock.elapsedRealtime();
                    if (delay <= 0) {
                        Log.w(TAG, "Shutdown broadcast ACTION_SHUTDOWN_IPO timed out");
                        if (mShutdownFlow == IPO_SHUTDOWN_FLOW) {
                            Log.d(TAG, "change shutdown flow from ipo to normal: ACTION_SHUTDOWN_IPO timeout");
                            mShutdownFlow = NORMAL_SHUTDOWN_FLOW;
                        }
                        break;
                    }
                    try {
                        mActionDoneSync.wait(delay);
                    } catch (InterruptedException e) {
                    }
                }
            }
        }

        if (mShutdownFlow != IPO_SHUTDOWN_FLOW) {
            // power off auto test, don't modify
            Log.i(TAG, "Shutting down activity manager...");

            final IActivityManager am =
                ActivityManagerNative.asInterface(ServiceManager.checkService("activity"));
            if (am != null) {
                try {
                    am.shutdown(MAX_BROADCAST_TIME);
                } catch (RemoteException e) {
                }
            }
        }

        // power off auto test, don't modify
        // Shutdown radios.
        Log.i(TAG, "Shutting down radios...");
        shutdownRadios(MAX_RADIO_WAIT_TIME);

        // power off auto test, don't modify
        Log.i(TAG, "Shutting down MountService...");
        if ( (mShutdownFlow == IPO_SHUTDOWN_FLOW) && (command.equals("1")||command.equals("3")) ) {
            Log.i(TAG, "bypass MountService!");
        } else {
            // Shutdown MountService to ensure media is in a safe state
            IMountShutdownObserver observer = new IMountShutdownObserver.Stub() {
                public void onShutDownComplete(int statusCode) throws RemoteException {
                    Log.w(TAG, "Result code " + statusCode + " from MountService.shutdown");
                    if (statusCode < 0) {
                        mShutdownFlow = NORMAL_SHUTDOWN_FLOW; 
                    }
                    actionDone();
                }
            };

            

            // Set initial variables and time out time.
            mActionDone = false;
            final long endShutTime = SystemClock.elapsedRealtime() + MAX_SHUTDOWN_WAIT_TIME;
            synchronized (mActionDoneSync) {
                try {
                    final IMountService mount = IMountService.Stub.asInterface(
                            ServiceManager.checkService("mount"));
                    if (mount != null) {
                        mount.shutdown(observer);
                    } else {
                        Log.w(TAG, "MountService unavailable for shutdown");
                    }
                } catch (Exception e) {
                    Log.e(TAG, "Exception during MountService shutdown", e);
                }
                while (!mActionDone) {
                    long delay = endShutTime - SystemClock.elapsedRealtime();
                    if (delay <= 0) {
                        Log.w(TAG, "Shutdown wait timed out");
                        if (mShutdownFlow == IPO_SHUTDOWN_FLOW) {
                            Log.d(TAG, "change shutdown flow from ipo to normal: MountService");
                            mShutdownFlow = NORMAL_SHUTDOWN_FLOW;
                        }
                        break;
                    }
                    try {
                        mActionDoneSync.wait(delay);
                    } catch (InterruptedException e) {
                    }
                }
            }
        }

        // power off auto test, don't modify
        //mountSerivce ���
        Log.i(TAG, "MountService shut done...");
        // [MTK] fix shutdown animation timing issue
        //==================================================================
        try {
            SystemProperties.set("service.shutanim.running","1");
            Log.i(TAG, "set service.shutanim.running to 1");

        } catch (Exception ex) {
            Log.e(TAG, "Failed to set 'service.shutanim.running' = 1).");
        }
        //==================================================================

        if (mShutdownFlow == IPO_SHUTDOWN_FLOW) {
            if (SHUTDOWN_VIBRATE_MS > 0) {
                // vibrate before shutting down
                Vibrator vibrator = new SystemVibrator();
                try {
                    vibrator.vibrate(SHUTDOWN_VIBRATE_MS);
                } catch (Exception e) {
                    // Failure to vibrate shouldn't interrupt shutdown.  Just log it.
                    Log.w(TAG, "Failed to vibrate during shutdown.", e);
                }

                // vibrator is asynchronous so we need to wait to avoid shutting down too soon.
                try {
                    Thread.sleep(SHUTDOWN_VIBRATE_MS);
                } catch (InterruptedException unused) {
                }
            }

            // Shutdown power
            // power off auto test, don't modify
            Log.i(TAG, "Performing ipo low-level shutdown...");

            delayForPlayAnimation();

            if (sInstance.mScreenWakeLock != null && sInstance.mScreenWakeLock.isHeld()) {
                sInstance.mScreenWakeLock.release();
                sInstance.mScreenWakeLock = null;
            }

            sInstance.mHandler.removeCallbacks(mDelayDim); 
            stMgr.shutdown(mContext);
            stMgr.finishShutdown(mContext);

            //To void previous UI flick caused by shutdown animation stopping before BKL turning off         
            if (pd != null) {
                pd.dismiss();
                pd = null;
            } else if (beginAnimationTime > 0) {
                try {
                    SystemProperties.set("service.bootanim.exit","1");
                    Log.i(TAG, "set 'service.bootanim.exit' = 1).");
                } catch (Exception ex) {
                    Log.e(TAG, "Failed to set 'service.bootanim.exit' = 1).");
                }  
                //SystemProperties.set("ctl.stop","bootanim");
            }

            synchronized (sIsStartedGuard) {
                sIsStarted = false;
            }

            sInstance.mPowerManager.setBacklightBrightnessOff(false); 
            sInstance.mCpuWakeLock.acquire(2000); 

            synchronized (mShutdownThreadSync) {
                try {
                    mShutdownThreadSync.wait();
                } catch (InterruptedException e) {
                }
            }
        } else {
            rebootOrShutdown(mReboot, mRebootReason);
        }
    }

这个方法做了一些列的操作，会关闭一些操作，如：

1. shutdownRadios(MAX_RADIO_WAIT_TIME);
2. mount.shutdown(observer);
3. stMgr.shutdown(mContext);

重点看 rebootOrShutdown(mReboot, mRebootReason);这个方法；准备重启的方法；

Step 7：来看看rebootOrShutdown（）这个方法：

public static void rebootOrShutdown(boolean reboot, String reason) {
        if (reboot) {
            Log.i(TAG, "Rebooting, reason: " + reason);
            if ( (reason != null) && reason.equals("recovery") ) {
                delayForPlayAnimation();
            }
            try {
                PowerManagerService.lowLevelReboot(reason);
            } catch (Exception e) {
                Log.e(TAG, "Reboot failed, will attempt shutdown instead", e);
            }
        } else if (SHUTDOWN_VIBRATE_MS > 0) {
            // vibrate before shutting down
            Vibrator vibrator = new SystemVibrator();
            try {
                vibrator.vibrate(SHUTDOWN_VIBRATE_MS);
            } catch (Exception e) {
                // Failure to vibrate shouldn't interrupt shutdown.  Just log it.
                Log.w(TAG, "Failed to vibrate during shutdown.", e);
            }

            // vibrator is asynchronous so we need to wait to avoid shutting down too soon.
            try {
                Thread.sleep(SHUTDOWN_VIBRATE_MS);
            } catch (InterruptedException unused) {
            }
        }

        delayForPlayAnimation();
        // Shutdown power
        // power off auto test, don't modify
        Log.i(TAG, "Performing low-level shutdown...");
        //PowerManagerService.lowLevelShutdown();
        //add your func: HDMI off
        //add for MFR
        try {
            if (ImHDMI == null)
                ImHDMI=MediatekClassFactory.createInstance(IHDMINative.class);
        } catch (Exception e) {
            e.printStackTrace();		    
        }
        ImHDMI.hdmiPowerEnable(false);
        try {
            if (mTvOut == null)
                mTvOut =MediatekClassFactory.createInstance(ITVOUTNative.class);
        } catch (Exception e) {
            e.printStackTrace();		    
        }

        mTvOut.tvoutPowerEnable(false);
        //add your func: HDMI off
        //unmout data/cache partitions while performing shutdown

        SystemProperties.set("ctl.start", "shutdown");

        /* sleep for a long time, prevent start another service */
        try {
            Thread.currentThread().sleep(Integer.MAX_VALUE);
        } catch ( Exception e) {
            Log.e(TAG, "Shutdown rebootOrShutdown Thread.currentThread().sleep exception!");  
        }
    }

关机震动也在这个方法里面；这个方法重点看PowerManagerService.lowLevelReboot(reason);

Log.i(TAG, "Rebooting, reason: " + reason);这句log也很重要，可以有助于我们分析代码；

Step 8：下面来看看PowerManagerServices.java这个类的lowLevelReboot（）这个方法：

public static void lowLevelReboot(String reason) throws IOException {
        nativeReboot(reason);
    }

这个方法调用到了native里面，后面的操作我就不分析了。。。

大致流程是：

关机，然后开机，底层判断节点后进入恢复出厂模式，recevory.img释放完全后，进入开机的流程。。。

以后有进展再补充这部分的流程，整个过程大致就是这个样子了，里面的细节有好多没有分析，大家可以自行研究。。。，抛砖引玉的目的达到了。