一插上USB外设以后 直接跳到相应的…

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

    </application>


加上：  
<intent-filter>
                <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED"></action>
            </intent-filter>

就可以了