USB权限，无提示 [英] USB Permissions without prompt

问题描述

我的应用程序中有2个活动.说FirstActivity和SecondActivity. FirstActivity是MAIN和LAUNCHER活动. SecondActivity使用USB设备.我希望USB许可提示仅在应用程序的生命周期内出现一次.

I have 2 activities within my app. Say FirstActivity and SecondActivity. FirstActivity is the MAIN and LAUNCHER activity. SecondActivity uses usb devices. I want the prompt for USB permission to appear only once within lifetime of the app.

如果只有一个Activity，清单中的以下几行可以解决我的目的:

If there was only one Activity, the following lines in manifest solved my purpose:

<activity android:name=".FirstActivity">
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
        <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/usb_device_filter" />
</activity>

这是在做以下事情:

1. 只要连接了USB设备(在xml中提到)且应用尚未打开，就启动FirstActivity.
2. 提示USB设备权限仅出现一次.

如何修改此设置以实现以下目标:

How do I modify this to achieve the following:

1. 如果SecondActivity已经在运行并且连接了新的USB设备，则我必须能够使用该设备而无需重新启动该应用程序.因此，我为广播接收器编写了如下内容:

1. If SecondActivity is already running and a new usb device is attached, I must be able to use the device without relaunching the app. So I have written a broadcast receiver for the same as follows:

public class TriggerReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        if (intent.getAction().equals(UsbManager.ACTION_USB_DEVICE_ATTACHED)) { 
        read connected usb devices and register serial port call listener back.
    }
}    

但是问题是在SecondActivity运行时连接USB设备时FirstActivity重新启动.如何避免这种情况?

But the problem is FirstActivity gets relaunched again when usb device is attached while SecondActivity is running. How do I avoid this ?

如果需要，将添加更多信息.感谢您的帮助.

Will add more information if needed. Would be thankful for any help.

推荐答案

尝试从FirstActivity中删除"意图过滤器<action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />，如

Try "remove" intent filter <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" /> from FirstActivity like in this question

更新

FirstActivity在每个USB_DEVICE_ATTACHED(甚至正在运行SecondActivity)上触发，因为您在AndroidManifest.xml文件中为其设置了<action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />过滤器.因此，当SecondActivity运行时，应禁用此过滤器.您可以通过这种方式做到这一点:

FirstActivity triggers on every USB_DEVICE_ATTACHED (even SecondActivity is running) because You set <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" /> filter for it in AndroidManifest.xml file. So You should disable this filter when SecondActivity running. You can do this by that way:

1)将AndroidManifest.xml中的(例如AliasFirstActivity)添加到FirstActivity，然后将<action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />过滤器移至别名描述(您应从FirstActivity描述中删除<action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />)，如下所示:

1) add (e.g. AliasFirstActivity) in AndroidManifest.xml to your FirstActivity and move <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" /> filter to alias description (You should remove <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />from FirstActivity description) like that:

        <activity-alias
            android:targetActivity=".FirstActivity"
            android:name=".AliasFirstActivity"
            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-alias>

2)将此代码添加到SecondActivity的onCreate()(或onResume())

2) add this code to onCreate() (or to onResume()) of SecondActivity

PackageManager pm = getApplicationContext().getPackageManager();
        ComponentName compName =
                new ComponentName(getPackageName(), getPackageName() + ".AliasFirstActivity");
        pm.setComponentEnabledSetting(
                compName,
                PackageManager.COMPONENT_ENABLED_STATE_DISABLED,
                PackageManager.DONT_KILL_APP);

抑制FirstActivity的意图过滤器USB_DEVICE_ATTACHED.您应该在SecondActivity中包含以下内容:

to suppress intent filter USB_DEVICE_ATTACHED for FirstActivity. You should have in SecondActivity something like that:

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);

        triggerReceiver = new TriggerReceiver();

        IntentFilter filter = new IntentFilter();
        filter.addAction(UsbManager.ACTION_USB_DEVICE_ATTACHED);
        registerReceiver(triggerReceiver, filter);

        PackageManager pm = getApplicationContext().getPackageManager();
        ComponentName compName =
                new ComponentName(getPackageName(), getPackageName() + ".AliasFirstActivity");
        pm.setComponentEnabledSetting(
                compName,
                PackageManager.COMPONENT_ENABLED_STATE_DISABLED,
                PackageManager.DONT_KILL_APP);
    }

那应该可以解决您的问题. 3)如果需要，可以使用以下代码在SecondActivity的onDestroy()(或onPause())中为FirstActivity的<action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />过滤器还原:

That should solve Your issue. 3) if it is needed, You can restore <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" /> filter for FirstActivity in onDestroy() (or in onPause()) of SecondActivity by using this code:

    PackageManager pm = getApplicationContext().getPackageManager();
    ComponentName compName =
            new ComponentName(getPackageName(), getPackageName() + ".AliasFirstActivity");
    pm.setComponentEnabledSetting(
            compName,
            PackageManager.COMPONENT_ENABLED_STATE_ENABLED,
            PackageManager.DONT_KILL_APP);

这篇关于USB权限，无提示的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！