Android UsbManager 获取不到HID设备

已经在AndroidManifest.xml配置了

<uses-permission android:name="android.hardware.usb.host" />
<uses-permission android:name="android.hardware.usb.accessory" />
<uses-feature android:name="android.hardware.usb.host" android:required="true" />

安卓手机中添加了

<?xml version="1.0" encoding="utf-8"?>
<permissions>   
<feature name="android.hardware.usb.host" />
</permissions>

下面是部分代码

UsbManager manager = (UsbManager) getSystemService(Context.USB_SERVICE);

HashMap<String, UsbDevice> deviceList = manager.getDeviceList();

Iterator<UsbDevice> deviceIterator = deviceList.values().iterator();

int count =deviceList.size();//当外接U盘时,此处是1,当外接鼠标或自己的HID设备时,此处是0,搜索了一下资料,说是UsbManager的源码,里面有一个过滤名单,只要是设备的subclass=1都获取不到,但一直没找到subclass=1在哪 

http://www.2cto.com/kf/201305/211304.html