Android USB Host read/write a file in USB device OTG [duplicate]

Question

I am trying to use the android host api for USB storage. I have many doubts regarding same.

1. What all things are possible using host api. I want to see the content of USB and if possible so the normal file operation. I didnt find any documentation help regarding this.

2. I am able to claimInterface using UsbDeviceConnection class API but I'm unable to understand how the bulkTransfer works so if anyone can guide me or give some reference I will try myself.

I tried reading the USB specification also, I understood how bulkTransfer works at USB level but unable to relate how android/java file operations are possible using bulkTransfer which using UsbEndpoint not the File Descriptor.

Thanks in Advance !!

Answer 1

The Android USB Host APIs do not include USB Mass Storage filesystem code, nor as of this writing in 2014 will "stock" Android mount a USB Mass Storage volume at operating system level.

To access a USB Mass Storage device using the stock Android USB Host APIs, you must therefore implement in your Application code both the necessary raw-USB operations to achieve block-level device access, and the appropriate filesystem logic itself. Needless to say, the details of such are of a complexity beyond the scope of an answer here, but you could start by studying documentation or existing implementations of USB Mass Storage drivers and filesystem drivers for other platforms.

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It appears the situation in Android 6 may be different, and access via the USB host apis to something that version recognizes as a storage device might even no longer be permitted. Those targeting Android 6+ may need to look elsewhere, but older devices will remain in use for some time.