Question

我正在为UsbInterfacing构建一个应用程序，我需要在我的应用程序运行时连续枚举USB设备..我需要在连接和断开连接时得到通知..我的usb设备的供应商ID是1204，product-id是64905 ..枚举有效一次。拔下设备并将其重新插入后，将无法工作.Below是我的代码：

        package com.example.enumerate; 

        import java.util.HashMap;
        import java.util.Iterator;
        import android.hardware.usb.UsbDevice;
        import android.hardware.usb.UsbManager;
        import android.os.Bundle;
        import android.widget.Toast;
        import android.app.Activity;
        import android.content.Context;

        public class Enumerate extends Activity {

            UsbDevice device;
            Iterator<UsbDevice> deviceIterator;

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

            }
//My onResume method
            @Override
            protected void onResume() 
            {
                super.onResume();
                UsbManager manager = (UsbManager) getSystemService(Context.USB_SERVICE);
                HashMap<String, UsbDevice> deviceList = manager.getDeviceList();
                deviceIterator = deviceList.values().iterator();
             //my UsbIterator    
            while(deviceIterator.hasNext())
            {
                    device = deviceIterator.next(); 
            }
                if(device.getProductId()==64905) //my device ProductId
                {
                    Toast t=Toast.makeText(this,"Connected",2000);
                    t.show();

                }
                else
                {
                    Toast t=Toast.makeText(this,"Not Connected",2000);
                }
                }


        }

Answer 1

您需要创建一个BroadcastReceiver来侦听系统在连接或分离设备时发送的各种广播操作。 UsbManager文档显示了各种动作常量。

内部Activity类的基本模板BroadcastReceiver可能如下所示......

public class MyActivity extends Activity {

    MyReceiver myReceiver = null;
    IntentFilter intentFilter = null;
    boolean isReceiverRegistered = false;

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

        intentFilter = new IntentFilter();
        // Add any or all of the following 'actions' to the IntentFilter
        // depending on what you need to track.
        intentFilter.addAction(UsbManager.ACTION_USB_ACCESSORY_ATTACHED);
        intentFilter.addAction(UsbManager.ACTION_USB_ACCESSORY_DETACHED);
        intentFilter.addAction(UsbManager.ACTION_USB_DEVICE_ATTACHED);
        intentFilter.addAction(UsbManager.ACTION_USB_DEVICE_DETACHED);
    }

    @Override
    protected void onResume() {
        super.onResume();

        if (!isReceiverRegistered) {
            myReceiver = new MyReceiver();
            registerReceiver(myReceiver, intentFilter);
            isReceiverRegistered = true;
        }
    }

    @Override
    protected void onPause() {
        super.onPause();

        if (isReceiverRegistered) {
            unregisterReceiver(myReceiver);
            myReceiver = null;
            isReceiverRegistered = false;
        }
    }

    private class MyReceiver extends BroadcastReceiver {

        @Override
        protected void onReceive(Context context, Intent intent) {
            String action, accessory, device, permissionGranted;

            action = intent.getAction();

            // Make sure you check to see if any of the strings are null
            // just in case the Intent isn't carrying any of them
            accessory = intent.getStringExtra(UsbManager.EXTRA_ACCESSORY);
            device = intent.getStringExtra(UsbManager.EXTRA_DEVICE);
            permissionGranted = intent.getStringExtra(UsbManager.EXTRA_PERMISSION_GRANTED);

            // Do what you need to do based on the action and extras...
        }
    }
}

无论何时在我的应用程序运行时连接usb设备都无法枚举

1 个答案: