AndroidFramework常见解决方案（14）修改默认usb连接模式为MTP模式

1 原理

Android P Q:找到UsbDeviceManager，这里在finishBoot（也就是启动后） 设置usb模式为 MTP模式，同时在处理消息时如果为默认模式NONE则将其更改为MTP模式。

2 修改方案（Android P Q）

修改文件为：frameworks/base/services/usb/java/com/android/server/usb/UsbDeviceManager.java，修改内容为：

//...//1 消息处理部分public void handleMessage(Message msg) {switch (msg.what) {case MSG_UPDATE_STATE:mCOnnected= (msg.arg1 == 1);mCOnfigured= (msg.arg2 == 1);updateUsbNotification(false);updateAdbNotification(false);if (mBootCompleted) {updateUsbStateBroadcastIfNeeded(getAppliedFunctions(mCurrentFunctions));}if ((mCurrentFunctions & UsbManager.FUNCTION_ACCESSORY) != 0) {updateCurrentAccessory();}if (mBootCompleted) {if (!mConnected && !hasMessages(MSG_ACCESSORY_MODE_ENTER_TIMEOUT)&& !hasMessages(MSG_FUNCTION_SWITCH_TIMEOUT)) {// restore defaults when USB is disconnectedif (!mScreenLocked&& mScreenUnlockedFunctions != UsbManager.FUNCTION_NONE) {setScreenUnlockedFunctions();} else {//这里将默认值UsbManager.FUNCTION_NONE改为UsbManager.FUNCTION_MTP//setEnabledFunctions(UsbManager.FUNCTION_NONE, false);setEnabledFunctions(UsbManager.FUNCTION_MTP, false);}}updateUsbFunctions();} else {mPendingBootBroadcast = true;}break;//...}
//...
}//2 finishboot部分protected void finishBoot() {if (mBootCompleted && mCurrentUsbFunctionsReceived && mSystemReady) {if (mPendingBootBroadcast) {updateUsbStateBroadcastIfNeeded(getAppliedFunctions(mCurrentFunctions));mPendingBootBroadcast = false;}if (!mScreenLocked&& mScreenUnlockedFunctions != UsbManager.FUNCTION_NONE) {setScreenUnlockedFunctions();} else {//这里将默认值UsbManager.FUNCTION_NONE改为UsbManager.FUNCTION_MTP//setEnabledFunctions(UsbManager.FUNCTION_NONE, false);setEnabledFunctions(UsbManager.FUNCTION_MTP, false);}if (mCurrentAccessory != null) {mUsbDeviceManager.getCurrentSettings().accessoryAttached(mCurrentAccessory);}updateUsbNotification(false);updateAdbNotification(false);updateUsbFunctions();}}