Android OTG。我无法获得设备列表;

时间:2019-01-24 06:08:22

标签: android usb-otg

我错了吗? 首先,我只想获取连接设备的列表:

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="mytest.otg">

    <uses-feature android:name="android.hardware.usb.host" />
    <uses-sdk android:minSdkVersion="12" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <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/device_filter" />
        </activity>
    </application>

</manifest>

res / xml / device_filter.xml

<?xml version="1.0" encoding="utf-8"?>

<resources>
    <usb-device />
</resources>

(我也尝试使用VID / PID)

MainActivity.java

package mytest.otg;

import android.content.Context;
import android.hardware.usb.UsbDevice;
import android.hardware.usb.UsbManager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;
import android.widget.Toast;

import java.util.HashMap;

public class MainActivity extends AppCompatActivity {

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

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

        HashMap< String, UsbDevice> deviceList = manager.getDeviceList();
      //  UsbDevice device = deviceList.get("deviceName");

        TextView t = (TextView) findViewById(R.id.text);

        t.setText( "devs: "+deviceList.size() );

        Toast.makeText( this, "devs: "+deviceList.size(), Toast.LENGTH_SHORT );

    }
}

但始终为0个设备。 (而且,Toast也未显示...)

我尝试过使用鼠标-设备正在使用它,但是我的应用程序-不可以。我做错了什么?

0 个答案:

没有答案