1.packages/apps/Settings / src/com/android/settings/deviceinfo/UsbBackend.java

getUsbDataMode() 中  // select none if no found

                                         return -1; // ...  《修改为 return 0; 或者                

                                                                        // select none if no found

                                                                        if (isTestSwitchOn()){                                                                             return 0;                                                                         }else{                                                                            return MODE_DATA_MTP;                                                                         } 》

2.frameworks/base / services/usb/java/com/android/server/usb/UsbDeviceManager.java

case MSG_UPDATE_STATE:

                    if (!mConnected) {

                        // When a disconnect occurs, relock access to sensitive user data                         mUsbDataUnlocked = false;                     }else if(mConnected){                         if(UsbManager.containsFunction(getDefaultFunctions(),UsbManager.USB_FUNCTION_MTP)){                            mUsbDataUnlocked = true;                         }                     }

 

 

//判断是否为测试模式：

    private boolean isTestSwitchOn(){

        try {                 final String configPath="//sys//class//android_usb//android0//usb_mode";                 FileInputStream inStream=new FileInputStream(configPath);                 byte[] buffer= new byte[1];                 int nu=inStream.read(buffer);                 inStream.close();                 if (nu > 0){                     if("1".equals(new String(buffer))){                         return true;                     }else {                         return false;                     }                 }else {                     return true;                 }             } catch (FileNotFoundException e) {                 e.printStackTrace();                 // default test mode without usb_mode file.                 return true;             } catch (IOException e) {                 e.printStackTrace();             }             return false;     }