android - 如何接收USB连接状态广播？

Question

我正在尝试在我的应用程序中检测 USB 连接，即 USB 是否已连接到设备。

正在 Marshmallow 6.0.1 (sdk23) 上测试

但我无法接收广播操作 ACTION_USB_DEVICE_ATTACHED 或 ACTION_USB_DEVICE_DETACHED..

我尝试同时使用动态方式和 AndroidManifest.xml 方式，都没有用..

这是我的代码:

AndroidManifest.xml:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.gokulnc.blah_blah"
    android:installLocation="auto"
    android:versionCode="15"
    android:versionName="1.5.1">

    <uses-feature android:name="android.hardware.usb.host" />

    <uses-sdk
        android:minSdkVersion="14"
        android:targetSdkVersion="23" />

    <android:uses-permission android:name="android.permission.USB_PERMISSION" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:vmSafeMode="false">

        <activity
            android:name=".MainActivity"
            android:label="@string/app_name"
            android:theme="@style/DrawerTheme">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>

            <receiver android:name="mUsbReceiver">
            <intent-filter>
                <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />
            </intent-filter>
            <intent-filter>
                <action android:name="android.hardware.usb.action.USB_DEVICE_DETACHED" />
            </intent-filter>
            </receiver>
        </activity>        
    </application>

</manifest>

MainActivity.java :

public class MainActivity extends AppCompatActivity {
    BroadcastReceiver mUsbReceiver;

    public void onCreate(Bundle savedInstanceState) {
        .....
        setBroadcastReceivers();
    }

    void setBroadcastReceivers() {
    //Reference: http://www.codepool.biz/how-to-monitor-usb-events-on-android.html

    mUsbReceiver = new BroadcastReceiver() {
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            Log.d(LOG_TAG, "Received Broadcast: "+action);
            if (UsbManager.ACTION_USB_DEVICE_ATTACHED.equals(action) || UsbManager.ACTION_USB_ACCESSORY_ATTACHED.equals(action)) {

                updateUSBstatus();
                Log.d(LOG_TAG, "USB Connected..");
            } else if (UsbManager.ACTION_USB_DEVICE_DETACHED.equals(action) || UsbManager.ACTION_USB_ACCESSORY_DETACHED.equals(action)) {
                UsbDevice device = (UsbDevice)intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
                if (device != null) {
                    updateUSBstatus();
                }
                Log.d(LOG_TAG, "USB Disconnected..");
            }
        }
    };

    IntentFilter filter = new IntentFilter();
    filter.addAction(UsbManager.ACTION_USB_DEVICE_ATTACHED);
    filter.addAction(UsbManager.ACTION_USB_DEVICE_DETACHED);
    //filter.addAction(UsbManager.ACTION_USB_ACCESSORY_ATTACHED);
    //filter.addAction(UsbManager.ACTION_USB_ACCESSORY_DETACHED);
    registerReceiver(mUsbReceiver , filter);
    Log.d(LOG_TAG, "mUsbReceiver Registered");
    }

    @Override
        public void onResume() {
            super.onResume();
            Log.d(LOG_TAG, "App Resumed..");
            //Refernce: https://stackoverflow.com/questions/18015656/cant-receive-broadcast-intent-of-usbmanager-action-usb-device-attached-usbmanag
            Intent intent = getIntent();
            if (intent != null) {
                if (intent.getAction().equals(UsbManager.ACTION_USB_DEVICE_ATTACHED)) {
                    Toast.makeText(getApplicationContext(), "Attached", Toast.LENGTH_SHORT).show();
                } else if(intent.getAction().equals(UsbManager.ACTION_USB_DEVICE_DETACHED)) {
                    Toast.makeText(getApplicationContext(), "Detached", Toast.LENGTH_SHORT).show();
                }
            }
        }
}

我还检查了这个答案:Can't receive broadcast Intent of UsbManager.ACTION_USB_DEVICE_ATTACHED/UsbManager.ACTION_USB_DEVICE_DETACHED , 但它没有帮助..

有人可以指出我哪里错了吗？

Answer 1

可能它不起作用的原因是，从 Android 6.0 开始，默认的 USB 模式是充电，并且在该模式下连接时，可能 ACTION_USB_DEVICE_ATTACHED 不会启动。

相反，现在我有了另一个解决方案:

String usbStateChangeAction = "android.hardware.usb.action.USB_STATE";

    @Override
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
        Log.d(LOG_TAG, "Received Broadcast: "+action);
        if(action.equalsIgnoreCase(usbStateChangeAction)) { //Check if change in USB state
            if(intent.getExtras().getBoolean("connected")) {
                // USB was connected
            } else {
                // USB was disconnected
            }
        }
    }

也就是说，只要 USB 状态发生切换，就会发送广播 android.hardware.usb.action.USB_STATE。

不像 android.hardware.usb.action.USB_DEVICE_ATTACHED 仅在启用 MTP 模式时广播，android.hardware.usb.action.USB_STATE 是每当它检测到能够连接到主机(比如计算机)的 USB 连接时广播，而不管其当前的 USB 模式，如充电、MTP 或其他任何模式。(更准确地说，它称为 USB 配置)