下面從framework層的ui來(lái)看一下插入usb后share的過程，這個(gè)動(dòng)作的觸發(fā)是從status bar下面彈出的usb connect開始的。

frameworks/base/packages/SystemUI

通過一系列反跟蹤，這個(gè)packages是系統(tǒng)級(jí)別的，用來(lái)展示系統(tǒng)的UI，當(dāng)插入usb線時(shí)，會(huì)在下方的status bar上會(huì)顯示usb連接圖標(biāo)。

????????USB connected

????????Select to copy files to/from your computer

點(diǎn)擊這個(gè)項(xiàng)后會(huì)談出 turn on USB storage

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資源所在路徑：

base/core/res/res/values/strings.xml

???<!-- USB_STORAGE: When the user connects the phoneto a computer via USB, we show a notification asking if he wants toshare files across.? This is the title-->

???<string name="usb_storage_notification_title">USBconnected</string>

???<!-- See USB_STORAGE. This is the message.-->

???<string name="usb_storage_notification_message">Selectto copy files to/from yourcomputer.</string>

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這兩個(gè)變量是在

/base/packages/SystemUI/src/com/android/systemui/usb/StorageNotification.java里邊被使用

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StorageNotification.java

主要用來(lái)處理存儲(chǔ)設(shè)備相關(guān)動(dòng)作的狀態(tài)更新、通知。主要涉及兩個(gè)方面：一是插入usb cabel后的狀態(tài)欄更新，主要針對(duì)ums功能。二是storage狀態(tài)發(fā)生改變時(shí)，會(huì)調(diào)用這個(gè)activity，如mount、unmount等。

所以入口主要有兩個(gè)：onUsbMassStorageConnectionChanged和onStorageStateChanged分別處理usb連接狀態(tài)的改變和storage狀態(tài)的改變。

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一 注冊(cè)StorageManager存儲(chǔ)設(shè)備狀態(tài)變更監(jiān)聽器StorageNotification

??????Storagenotification這個(gè)activity是怎么被啟動(dòng)的呢？從而觸發(fā)了usb connect changed的函數(shù)動(dòng)作？

是通過下面的監(jiān)聽器注冊(cè)來(lái)完成的。

frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/tablet/TabletStatusBarPolicy.java

// storage

???????mStorageManager = (StorageManager)context.getSystemService(Context.STORAGE_SERVICE);

???????mStorageManager.registerListener(

???????????????newcom.android.systemui.usb.StorageNotification(context));

這個(gè)將StorageNotification注冊(cè)到mStorageManager的listener中，沒有理解listener的機(jī)制。但是猜測(cè)應(yīng)該是當(dāng)listenser到某個(gè)消息時(shí)會(huì)啟動(dòng)這個(gè)注冊(cè)的activity。

注冊(cè)StorageManager的存儲(chǔ)設(shè)備狀態(tài)變更監(jiān)聽器來(lái)實(shí)現(xiàn)的。

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二 針對(duì)usb線連接動(dòng)作的通知

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??????在storageNotification這個(gè)類的構(gòu)造函數(shù)中，直接調(diào)用了下面這個(gè)usb 連接狀態(tài)的處理函數(shù)，onUsbMassStorageConnectionChanged(connected);通過和上面的聯(lián)系起來(lái)就是，當(dāng)監(jiān)聽器監(jiān)聽到變化后，開始啟動(dòng)這個(gè)activity，構(gòu)造函數(shù)開始執(zhí)行，執(zhí)行一系列動(dòng)作，包括對(duì)usb狀態(tài)的處理，以及后面將會(huì)遇到的storage狀態(tài)的處理。??

2.1 構(gòu)造函數(shù)：

???public StorageNotification(Context context) {

???????mContext = context;

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???????mStorageManager = (StorageManager)context.getSystemService(Context.STORAGE_SERVICE);

???????final boolean connected =mStorageManager.isUsbMassStorageConnected();

???????Slog.d(TAG, String.format( "Startup with UMS connection %s (mediastate %s)", mUmsAvailable,

???????????????Environment.getExternalStorageState()));

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???????HandlerThread thr = new HandlerThread("SystemUIStorageNotification");

???????thr.start();

???????mAsyncEventHandler = new Handler(thr.getLooper());

???????mUsbNotifications = new HashSet();

???????mLastState = Environment.MEDIA_MOUNTED;

???????mLastConnected = false;

???????onUsbMassStorageConnectionChanged(connected);

??????????????????……………………

???????

???????StorageVolume[] volumes =mStorageManager.getVolumeList();

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???????for (int i=0; i<volumes.length; i++) {

???????????String sharePath = volumes[i].getPath();

???????????String shareState =mStorageManager.getVolumeState(sharePath);

???????????Slog.d(TAG, "onStorageStateChanged - sharePath: " + sharePath + "shareState: " + shareState);

???????????if(shareState.equals(Environment.MEDIA_UNMOUNTABLE)) {

???????????????onStorageStateChanged(sharePath,shareState, shareState);

???????????

???????????}

???????}

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2.2?onUsbMassStorageConnectionChanged

???

???@Override

???public void onUsbMassStorageConnectionChanged(finalboolean connected) {

???????mAsyncEventHandler.post(new Runnable() {

???????????@Override

???????????public void run() {

???????????????onUsbMassStorageConnectionChangedAsync(connected);

???????????}

???????});

???}

2.3?onUsbMassStorageConnectionChangedAsync

???private void onUsbMassStorageConnectionChangedAsync(booleanconnected) {

?????????????mUmsAvailable = connected;//插上usb ums就使能了，不合適啊，還得根據(jù)是否有mass_storage功能

?????????????另外這個(gè)函數(shù)中代碼明確表示ums的優(yōu)先級(jí)高于mtp。如果包含mass_storage功能，就發(fā)出status bar通知。

??????這個(gè)函數(shù)中的主要工作是調(diào)用updateUsbMassStorageNotification來(lái)更新status bar，但是采用什么機(jī)制來(lái)決定是否調(diào)用這個(gè)函數(shù)進(jìn)行更新，是會(huì)根據(jù)mtp/ums功能來(lái)選擇的，不同的產(chǎn)品應(yīng)該會(huì)有不同的機(jī)制。

?????????????這個(gè)status bar的更新機(jī)制，很容易被誤觸，有時(shí)并不需要ums功能，但是需要光盤功能，卻被誤打開。尤其是mtp+cdrom的狀態(tài)。

????

??? voidupdateUsbMassStorageNotification(booleanavailable) {

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???????if (available) {

???????????SXlog.d(TAG, "updateUsbMassStorageNotification -[true]");

???????????Intent intent = new Intent();

???????????intent.setClass(mContext, com.android.systemui.usb.UsbStorageActivity.class);

???????????intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

????????????????????

????????????????????//準(zhǔn)備出等待要執(zhí)行的activity，pi

???????????PendingIntent pi = PendingIntent.getActivity(mContext, 0, intent,0);

???????????setUsbStorageNotification(//在下面的status bar中顯示usb connect

???????????????????com.android.internal.R.string.usb_storage_notification_title,

???????????????????com.android.internal.R.string.usb_storage_notification_message,

???????????????????com.android.internal.R.drawable.stat_sys_data_usb,

???????????????????false, true, pi);

???????} else {

???????????SXlog.d(TAG, "updateUsbMassStorageNotification -[false]");

???????????setUsbStorageNotification(0, 0, 0, false, false, null);

???????} ??

???}??

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2.4?setUsbStorageNotification

???private synchronized void setUsbStorageNotification(int titleId, intmessageId, int icon,

???????????boolean sound, boolean visible,PendingIntent pi) {

?????????????組裝mUsbStorageNotification變量，最后通過notificationManager發(fā)出。

?????????這個(gè)函數(shù)在最后有下面的動(dòng)作，應(yīng)該是一個(gè)通知消息。

???????if (visible) {

???????????notificationManager.notify(notificationId,mUsbStorageNotification);

???????} else {

???????????notificationManager.cancel(notificationId);

???????}

??????在通過 notificationManager將mUsbStorageNotification發(fā)出時(shí)，會(huì)在status bar上出現(xiàn)提示條：usb connect，用戶點(diǎn)擊這個(gè)usb connect后，會(huì)彈出一個(gè)界面，提示用戶是否打開usb mass storage。另外mUsbStorageNotification有一個(gè)重要的pendingintent參數(shù)，用來(lái)提示是否直接執(zhí)行這個(gè)activity。

??????從這個(gè)函數(shù)的代碼及實(shí)驗(yàn)現(xiàn)象來(lái)看，是這樣設(shè)計(jì)的，如果沒有啟用adb，將直接彈出讓用戶使能ums的全屏(就是啟動(dòng)了pendingintent的activity)，如果使能了adb，不會(huì)自動(dòng)彈出來(lái)，需要用戶自己去展開status bar.

注意adb這部分的判斷信息：

???????????final boolean adbOn = 1 == Settings.Secure.getInt(

???????????????mContext.getContentResolver(),

???????????????Settings.Secure.ADB_ENABLED,

???????????????0);

注意這塊獲取的是黃色部分的信息。

下面是UsbDeviceManager.java中的部分

???????// make sure the ADB_ENABLED setting value matches the currentstate

???????Settings.Secure.putInt(mContentResolver,Settings.Secure.ADB_ENABLED, mAdbEnabled ? 1 : 0);

這個(gè)代碼是在啟動(dòng)啟動(dòng)systemReady中的，就是說當(dāng)用戶設(shè)置的默認(rèn)function中有adb功能時(shí)，將信息更新到Setting.Secure.ADB_ENABLED中，以便setting中同步。如果用戶在應(yīng)用中直接使用setprop的話，setting中是得不到更新的。

??????所以 UsbStorageActivity的啟動(dòng)有兩種方式，直接啟動(dòng)或者通過點(diǎn)擊usb connect啟動(dòng)。

點(diǎn)擊usbconect這個(gè)動(dòng)作，沒有找到代碼，猜測(cè)應(yīng)該是在notificationManager里邊處理了，因?yàn)榘ㄒ獑?dòng)的activity都在參數(shù)里邊了。

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2.5 UsbStorageActivity.java

packages/SystemUI/src/com/android/systemui/usb

下面是提示用戶打開ums的資源信息：

再看一下那個(gè)全屏顯示的窗口的信息：

frameworks/base/core/res/res/values/strings.xml

<stringname="usb_storage_button_mount">Turn on USBstorage</string>

<string name="usb_storage_message"product="default">You have connected to yourcomputer via USB. Touch the button below if you want to copy filesbetween your computer and your Android\u2018s SDcard.</string>

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frameworks/base/core/res/res/layout/usb_storage_activity.xml

android:text="@string/usb_storage_button_mount"

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所以整個(gè)的用戶交互的UI信息都在SystremUI這個(gè)系統(tǒng)app里邊。

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當(dāng)點(diǎn)擊turn on usbstorage時(shí)，logcat中，跟蹤到UsbStorageActivity:oncreatedialoge,這個(gè)tag在usbstorageactivity.java 中發(fā)現(xiàn)

UsbStorageActivity這個(gè)activity在updateUsbMassStorageNotification已經(jīng)做好準(zhǔn)備了，等待用戶turn on后立即啟動(dòng)。

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public Dialog onCreateDialog(int id, Bundle args){

???????Log.i(TAG, "onCreateDialoge");

???????switch (id) {

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???????case DLG_CONFIRM_KILL_STORAGE_USERS:

???????????return new AlertDialog.Builder(this)

???????????????????.setTitle(R.string.dlg_confirm_kill_storage_users_title)

???????????????????.setPositiveButton(R.string.dlg_ok,new DialogInterface.OnClickListener() {

???????????????????????public void onClick(DialogInterface dialog, int which) {

???????????????????????????????mHasCheck = false;

???????????????????????????switchUsbMassStorage(true);

???????????????????????}})

通過點(diǎn)擊確認(rèn)后回彈出一個(gè)alertdialog,確認(rèn)就是這個(gè)流程。資源信息在下面。當(dāng)點(diǎn)擊確定按鈕后將執(zhí)行switchUsbMassStorage。

???<!-- USB_STORAGE_KILL_STORAGE_USERSdialog? -->

???<string name="dlg_confirm_kill_storage_users_title">Turnon USB storage</string>

???<!-- USB_STORAGE_KILL_STORAGE_USERS dialog messagetext -->

???<stringname="dlg_confirm_kill_storage_users_text">If youturn on USB storage, some applications you are using will stop andmay be unavailable until you turn off USBstorage.</string>

onClick----checkStorageUsers---checkStorageUsersAsync

scheduleShowDialog

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2.6 switchUsbMassStorage

???private void switchUsbMassStorage(final boolean on) {

???????// things to do on the UI thread

???????mUIHandler.post(new Runnable() {

???????????@Override

???????????public void run() {

???????????????mUnmountButton.setVisibility(View.GONE);

???????????????mMountButton.setVisibility(View.GONE);

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???????????????mProgressBar.setVisibility(View.VISIBLE);

???????????????// will be hidden once USB mass storage kicks in (orfails)

???????????}

???????});

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???????// things to do elsewhere

???????mAsyncStorageHandler.post(new Runnable() {

???????????@Override

???????????public void run() {

???????????????if (on) {

???????????????????mSettingUMS = true;

???????????????????mStorageManager.enableUsbMassStorage();

???????????????} else {

???????????????????mSettingUMS = false;

???????????????????mStorageManager.disableUsbMassStorage();

???????????????}

???????????}

???????});

???}

2.7 StorageManager.java

??????frameworks/base/core/java/android/os/storage/StorageManager.java?

mStorageManager = (StorageManager)getSystemService(Context.STORAGE_SERVICE);

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???

???public void enableUsbMassStorage() {

???????try {

???????????mMountService.setUsbMassStorageEnabled(true);

???????} catch (Exception ex) {

???????????Log.e(TAG, "Failed to enable UMS", ex);

???????}

???}

mMountService.setUsbMassStorageEnabled(true)(ImountService.java)

???????mMountService =IMountService.Stub.asInterface(ServiceManager.getService("mount"));

下面沒有跟蹤下去，猜想應(yīng)該會(huì)在vold里邊完成，但是怎么傳達(dá)下去的呢？在mountservice.java中也有setUsbMassStorageEnabled函數(shù)，這個(gè)是services目錄下面的。這個(gè)函數(shù)里邊是我們要找的。

2.8 mountservice.java

/framework/base/services/java/com/android/server/mountservice.java

???public void setUsbMassStorageEnabled(boolean enable){

?????????????………………

???????????} else if (enable &&state.equals(Environment.MEDIA_UNMOUNTED)) {

?????????????? doShareUnshareVolume(path, method,enable);

???????????}

??????將所有的volume都進(jìn)行處理，方法為”ums”。

2.9 Doshareunsharevolume

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???private void doShareUnshareVolume(String path, Stringmethod, boolean enable) {

???????// TODO: Add support for multiple share methods

???????if (!method.equals("ums")) {

???????????throw new IllegalArgumentException(String.format("Method %s notsupported", method));

???????}

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???????try {

???????????mConnector.doCommand(String.format(

???????????????????"volume %sshare %s %s",(enable ? "" : "un"), path, method));

???????} catch (NativeDaemonConnectorException e) {

???????????Slog.e(TAG, "Failed to share/unshare", e);

???????}

???}

????????上面紅色的就是傳達(dá)下去的命令及參數(shù)

2.10 comandlistener.cpp

system/vold/comandlistener.cpp

----àmconnector.docommand,命令應(yīng)該對(duì)應(yīng)volume，不同的是對(duì)應(yīng)的命令為volume命令集。

mconnector.doCommand進(jìn)入nativedaemonconnector.java?docommand--à

經(jīng)過jni進(jìn)入到comandlistener.cpp該文件位于system/vold文件夾內(nèi)，有各種命令的監(jiān)聽處理，cdrom、volume、storage等。

??? }else if (!strcmp(argv[1], "share")) {

???????if (argc != 4) {

???????????cli->sendMsg(ResponseCode::CommandSyntaxError,

???????????????????"Usage: volume share <path><method>", false);

???????????return 0;

???????}

???????rc= vm->shareVolume(argv[2],argv[3]);

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2.11?VolumeManager.cpp

#define MASS_STORAGE_FILE_PATH?"/sys/class/android_usb/android0/f_mass_storage/lun/file"

#defineMASS_STORAGE_EXTERNAL_FILE_PATH?"/sys/class/android_usb/android0/f_mass_storage/lun1/file"

int VolumeManager::shareVolume(const char *label, const char*method) {

分別對(duì)內(nèi)置和外置sd卡都作了處理，看來(lái)只支持2個(gè)。

???if(primaryStorage) {

???????if ((fd = open(MASS_STORAGE_FILE_PATH, O_WRONLY)) <0) {

???????????SLOGE("Unable to open ums lunfile (%s)",strerror(errno));

???????????return -1;

???????}

???}

???else

???{

???????if ((fd = open(MASS_STORAGE_EXTERNAL_FILE_PATH, O_WRONLY))< 0) {

???????????SLOGE("Unable to open ums lunfile (%s)",strerror(errno));

???????????return -1;

???????}

???}

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??? if(write(fd, nodepath, strlen(nodepath)) < 0){

???????SLOGE("Unable to write to ums lunfile (%s)",strerror(errno));

???????close(fd);

???????return -1;

???}

到此完成了back-file的對(duì)應(yīng)。

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2.12 流程圖

三介質(zhì)狀態(tài)發(fā)生改變的處理

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???這個(gè)函數(shù)是當(dāng)存儲(chǔ)介質(zhì)的狀態(tài)發(fā)生改變時(shí)，會(huì)被調(diào)用。調(diào)用主要發(fā)生在StorageManager.java,MountService.java,?UsbStorageActivity.java等一下文件中。

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??????public void onStorageStateChanged(final String path,final String oldState, final String newState) {

???????mAsyncEventHandler.post(new Runnable() {

???????????@Override

???????????public void run() {

???????????????onStorageStateChangedAsync(path, oldState, newState);

???????????}

???????});

???}

??????存儲(chǔ)的狀態(tài)發(fā)生變化，如掛載完成了、卸載了、等等，所以當(dāng)掛載完成后，也會(huì)去調(diào)用更新。

???private void onStorageStateChangedAsync(String path,String oldState, String newState) {

???????Slog.i(TAG, String.format(

???????????????"Media {%s} state changed from {%s} -> {%s}", path,oldState, newState));

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???????mLastState = newState;

???????StorageVolume volume = null;

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???????StorageVolume[] Volumes =mStorageManager.getVolumeList();???????????

???????for(int i = 0; i < Volumes.length; i++){

??????????? if(Volumes[i].getPath().equals(path)){

??????????????volume = Volumes[i];

?????????????????break;???????????????

???????????}

???????}????

?????????????if (volume == null) {

????????????????????? ?Slog.e(TAG,String.format(

???????????????"Can NOT find volume by name {%s}", path));

?????????????????????? return;

?????????????}

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???????if (newState.equals(Environment.MEDIA_SHARED)) {

??????……………………

???????} else if (newState.equals(Environment.MEDIA_MOUNTED)) {

???????????

???????????SXlog.d(TAG, "onStorageStateChangedAsync -[MEDIA_MOUNTED]");

???????????setMediaStorageNotification(path, 0, 0, 0, false, false,null);

???????????updateUsbMassStorageNotification(mUmsAvailable);

???????????????????//掛載成功后，就會(huì)調(diào)用更新函數(shù)，并且只要usb連接著就更新。難道是有些場(chǎng)景usb一直連接著，但是發(fā)生了介質(zhì)重新mounted的情況，所以需要update。

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???????????if("/mnt/sdcard".equals(path)) {

???????????????mUsbNotifications.clear();

???????????}

???????}

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todo：//storage的邏輯思路，需要詳細(xì)看下面兩個(gè)文件：

base/core/java/android/os/storage/StorageManager.java

base/services/java/com/android/server/mountservice.java

framework是android向應(yīng)用程序開發(fā)提供的一個(gè)框架，簡(jiǎn)單理解為API.她創(chuàng)建了一系列的class對(duì)象，通過這些對(duì)象的接口行為，來(lái)操作各種組件功能。Framework根據(jù)產(chǎn)品的功能及用戶的行為抽象出了各種組件，應(yīng)用程序開發(fā)可以直接調(diào)用。那么framework的設(shè)計(jì)也是有一個(gè)框架的，是一個(gè)獨(dú)立的層。麻雀雖小，五臟俱全。

frameworks/base 這個(gè)目錄下是framework的基本代碼，基本代碼中的core目錄，顧名思義應(yīng)該是框架的核心骨架代碼。這個(gè)骨架的實(shí)現(xiàn)是需要java和cpp的，其間通過jni來(lái)實(shí)現(xiàn)調(diào)用。其中services目錄是為framework中功能提供后臺(tái)服務(wù)用的，上層應(yīng)用是調(diào)用不到的。

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問題分析試驗(yàn)記錄：

1 使用當(dāng)年的ums功能的，使能mass_storage,adb，acm時(shí)，ums可以使用，android_usb/f_mass_storage下面有相應(yīng)的設(shè)備backfile

2 當(dāng)使用mtp時(shí)，也是沒有看到相應(yīng)的設(shè)備文件。這個(gè)bin文件是比較早的，剛剛?cè)サ鬰drom的confirm dialog的。去掉對(duì)話框還是有bug的版本。當(dāng)插入usb cabel時(shí)，下方還顯示usb connect。這種情況下mtp進(jìn)入后看不到盤符。(usb connect后是不是做了什么)

設(shè)置setprop sys.usb.configmass_storage,adb,acm后，雖然可以切換成功，但是點(diǎn)擊turn on時(shí)，不會(huì)彈出alert對(duì)話框，并且backfile share不成功。

找到一部分原因：沒有定義MTK_MASS_STORAGE= yes時(shí)，在android.c中是不會(huì)創(chuàng)建節(jié)點(diǎn)的。mass_storage_function_init驗(yàn)證中。一直出現(xiàn)adboffline。并且usb connect又出現(xiàn)了。Ums和mtp共用的情況下會(huì)出現(xiàn)adb offline？

?

考慮到以前在mtp+cdrom的情況下是去掉usb connect顯示的，沒有adb也不要彈出usb mass_storage turn on 提示框的。但是這種情形下都出來(lái)了(MTK_MASS_STORAGE= yes)。

SetUsbStorageNotification在onStorageStateChangedAsync也被調(diào)用過。不過這個(gè)是判斷狀態(tài)為shared的情況，share成功后顯示Turn off USB storage。

?

???private void onStorageStateChangedAsync(String path, StringoldState, String newState) {

???????Slog.i(TAG, String.format(

???????????????"Media {%s} state changed from {%s} -> {%s}", path,oldState, newState));

?

???????mLastState = newState;

?

???????if (newState.equals(Environment.MEDIA_SHARED)) {

???????????

???????????SXlog.d(TAG, "onStorageStateChangedAsync -[MEDIA_SHARED]");

???????????Intent intent = new Intent();

???????????intent.setClass(mContext,com.android.systemui.usb.UsbStorageActivity.class);

???????????PendingIntent pi = PendingIntent.getActivity(mContext, 0, intent,0);

???????????setUsbStorageNotification(

???????????????????com.android.internal.R.string.usb_storage_stop_notification_title,

???????????????????com.android.internal.R.string.usb_storage_stop_notification_message,

???????????????????com.android.internal.R.drawable.stat_sys_warning, false, true,pi);

?

???????????if("/mnt/sdcard".equals(path)) {

???????????????mUsbNotifications.clear();

???????????}

???????}

到底是從哪里觸發(fā)的呢？

Bar中顯示也變?yōu)椤盋onnected as USB Storage”

./res/values/strings.xml:2859:???<stringname="usb_ums_notification_title">Connected as USBStorage</string>

./res/values/strings.xml:2855:???<stringname="usb_mtp_notification_title">Connected as amedia device</string>

./res/values/strings.xml:2863:???<stringname="usb_cd_installer_notification_title">Connectedas an installer</string>

這個(gè)更新是在UsbDeviceManager.java里邊完成的。

?? private voidupdateUsbNotification() {

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