访问连接的 MTP 设备而不接收 USB_DEVICE_ATTACHED Intent？

发布于 2024-12-08 06:42:19 字数 1263 浏览 6 评论 0原文

我正在开发一些应用程序，它使用媒体传输协议从连接到我的 Android 平板电脑 USB 主机（Android 3.1、Acer Iconia Tab A500）的相机读取照片。

我找到了一些描述如何使用 USB 的教程，并且我已经可以从 USB 摄像头复制到 SD 卡了。

我只有一个问题：所有教程都等待 USB_DEVICE_ATTACHED-Intent，然后打开 UsbDeviceConnection 以便与意图捆绑包中发送的设备进行通信。

所以我希望能够手动启动一个访问 USB 的活动 - 而不接收此意图。现在的问题是，我无法像这样打开 USBConnection

UsbDeviceConnection usbDeviceConnection = usbManager.openDevice(usbDevice);

它只是返回 null。如果我重新插入设备并选择我的活动作为意图接收器，它就可以正常工作。我想这一定是因为IntentReceiver对USB设备有一些独占的权限。

我的清单如下所示：

    <activity
        android:name=".ImageActivity"
        android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
        <intent-filter>
            <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />
        </intent-filter>
        <meta-data
            android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED"
            android:resource="@xml/device_filter" />
    </activity>

举个例子：如果用户将 Galery 设置为 USB 设备的默认设置，该怎么办？这种情况下如何访问USB设备呢？

原文

I´m working on some application which uses Media Transfer Protocol to read Photos from a Camera connected to my Android Tablets USB host (Android 3.1, Acer Iconia Tab A500).

I found some tutorials describing how to work with USB and I got copying from USB camera to SD-Card already working.

There is only one problem I have: All the tutorials wait for USB_DEVICE_ATTACHED-Intent and then open a UsbDeviceConnection for communicating with the device that is sent within the intents Bundle.

So I would like to be able to manually start an activity which accesses USB - WITHOUT receiving this intent.
The Problem now is, that I cannot open an USBConnection like this

UsbDeviceConnection usbDeviceConnection = usbManager.openDevice(usbDevice);

It simply returns null.
If I re-plugin the device and select my Activity as Intent receiver, it works fine.
I think this must be because of the IntentReceiver having some exclusive permissions on the USB device.

My Manifest looks like this:

    <activity
        android:name=".ImageActivity"
        android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
        <intent-filter>
            <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />
        </intent-filter>
        <meta-data
            android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED"
            android:resource="@xml/device_filter" />
    </activity>

So one example: What if a user has set Galery as default for USB devices. How can I access the USB device in this case?

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