可能您实际上需要阅读原始 USB 描述符来获取您想要的数据。这是我为自己的目的编写的基本 USB 设备发现程序。请注意,我正在寻找特定设备(Dajac Easy I/O 1000 数据采集系统),但您可以应用相同的原理。我会向您展示如何获取您正在寻找的数据。
这里首先是代码。我的包是usbtest3,文件是MainActivity.java:
package com.hotspotoffice.usbtest3;
// David Schofield, Hotspot Office, LLC., Pittsburgh, PA.
// Donations via PayPal always welcome! schofield (dot) david (at) verizon.net
import java.io.UnsupportedEncodingException;
import java.util.HashMap;
import java.util.Iterator;
import android.os.Bundle;
import android.app.Activity;
import android.app.PendingIntent;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.view.View;
import android.view.Menu;
import android.widget.Button;
import android.widget.TextView;
import android.hardware.usb.UsbConstants;
import android.hardware.usb.UsbManager;
import android.hardware.usb.UsbDevice;
import android.hardware.usb.UsbDeviceConnection;
import android.hardware.usb.UsbInterface;
public class MainActivity extends Activity {
protected static final int STD_USB_REQUEST_GET_DESCRIPTOR = 0x06;
// http://libusb.sourceforge.net/api-1.0/group__desc.html
protected static final int LIBUSB_DT_STRING = 0x03;
private static final String ACTION_USB_PERMISSION = "com.android.example.USB_PERMISSION";
private Button btnDiscover;
private TextView txtInfo;
private PendingIntent mPermissionIntent;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btnDiscover=(Button)findViewById(R.id.btnDiscover);
txtInfo=(TextView)findViewById(R.id.txtInfo);
mPermissionIntent = PendingIntent.getBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), 0);
IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION);
registerReceiver(mUsbReceiver, filter);
btnDiscover.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// txtInfo.setText("Button has been Pressed for "+(++i)+" Times.");
UsbManager manager = (UsbManager)getSystemService(Context.USB_SERVICE);
HashMap<String, UsbDevice> deviceList = manager.getDeviceList();
Iterator<UsbDevice> deviceIterator = deviceList.values().iterator();
while(deviceIterator.hasNext()){
UsbDevice device = deviceIterator.next();
manager.requestPermission(device, mPermissionIntent);
txtInfo.append("Model:" + device.getDeviceName() + "\n");
txtInfo.append("DeviceID:" + device.getDeviceId() + "\n");
txtInfo.append("Vendor:" + device.getVendorId() + "\n");
txtInfo.append("Product:" + device.getProductId() + "\n");
txtInfo.append("Class:" + device.getDeviceClass() + "\n");
txtInfo.append("Subclass:" + device.getDeviceSubclass() + "\n");
txtInfo.append("Protocol:" + device.getDeviceProtocol() + "\n");
UsbInterface intf = device.getInterface(0);
int epc = 0;
epc = intf.getEndpointCount();
txtInfo.append("Endpoints:" + epc + "\n");
txtInfo.append("Permission:" + Boolean.toString(manager.hasPermission(device)) + "\n");
UsbDeviceConnection connection = manager.openDevice(device);
if(null==connection){
txtInfo.append("(unable to establish connection)\n");
} else {
// Claims exclusive access to a UsbInterface.
// This must be done before sending or receiving data on
// any UsbEndpoints belonging to the interface.
connection.claimInterface(intf, true);
// getRawDescriptors can be used to access descriptors
// not supported directly via the higher level APIs,
// like getting the manufacturer and product names.
// because it returns bytes, you can get a variety of
// different data types.
byte[] rawDescs = connection.getRawDescriptors();
String manufacturer = "", product = "";
try
{
byte[] buffer = new byte[255];
int idxMan = rawDescs[14];
int idxPrd = rawDescs[15];
int rdo = connection.controlTransfer(UsbConstants.USB_DIR_IN
| UsbConstants.USB_TYPE_STANDARD, STD_USB_REQUEST_GET_DESCRIPTOR,
(LIBUSB_DT_STRING << 8) | idxMan, 0, buffer, 0xFF, 0);
manufacturer = new String(buffer, 2, rdo - 2, "UTF-16LE");
rdo = connection.controlTransfer(UsbConstants.USB_DIR_IN
| UsbConstants.USB_TYPE_STANDARD, STD_USB_REQUEST_GET_DESCRIPTOR,
(LIBUSB_DT_STRING << 8) | idxPrd, 0, buffer, 0xFF, 0);
product = new String(buffer, 2, rdo - 2, "UTF-16LE");
} catch (UnsupportedEncodingException e)
{
e.printStackTrace();
}
txtInfo.append("Manufacturer:" + manufacturer + "\n");
txtInfo.append("Product:" + product + "\n");
txtInfo.append("Serial#:" + connection.getSerial() + "\n");
}
txtInfo.append("------------------------------------\n");
}
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
private final BroadcastReceiver mUsbReceiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (ACTION_USB_PERMISSION.equals(action)) {
synchronized (this) {
UsbDevice device = (UsbDevice)intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false)) {
if(device != null){
//call method to set up device communication
}
}
else {
txtInfo.append("permission denied for device " + device);
}
}
}
}
};
}
我的清单文件包含 USB 主机设备支持的意图和要求:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.hotspotoffice.usbtest3"
android:versionCode="1"
android:versionName="1.0" >
<uses-feature android:name="android.hardware.usb.host" />
<uses-sdk
android:minSdkVersion="15"
android:targetSdkVersion="15" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.hotspotoffice.usbtest3.MainActivity"
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>
</application>
</manifest>
最后,您将需要一个设备过滤器。它位于 \res\xml\device_filter.xml 下 请注意,我必须自己在 \res 下创建 xml 文件夹。
<?xml version="1.0" encoding="utf-8"?>
<resources>
<usb-device vendor-id="7635" product-id="1" class="255" subclass="255" protocol="0" />
</resources>
请注意,所有字段都必须是十进制,而不是十六进制。您需要用您自己的设备替换您自己的供应商、产品、类和子类值。您可以使用“USB 主机视图”或“USB 设备信息”之类的程序来发现这些值。(从 Play 商店免费下载。)
最后,这是我在 Activity_Main.xml 中定义用户界面的方式。
您至少需要 Discover 按钮和用于输出的 TextMultiline。(忽略 Init 和 On/Off 按钮。)
顺便说一句,我使用的是 10 英寸东芝 Thrive 平板电脑,所以 YMMV。
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >
<EditText
android:id="@+id/txtInfo"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/btnDiscover"
android:layout_alignRight="@+id/textView1"
android:layout_centerVertical="true"
android:ems="10"
android:inputType="textMultiLine"
android:maxLines="50"
android:minLines="20"
android:minWidth="400dp" >
<requestFocus />
</EditText>
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="@+id/btnToggleDIO"
android:layout_marginLeft="192dp"
android:layout_toRightOf="@+id/btnDiscover"
android:text="@string/lblDIO"
android:textAppearance="?android:attr/textAppearanceMedium" />
<Button
android:id="@+id/btnDiscover"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/btnInit"
android:layout_alignBottom="@+id/btnInit"
android:layout_alignParentLeft="true"
android:layout_marginLeft="73dp"
android:text="@string/strDiscover" />
<ToggleButton
android:id="@+id/btnToggleDIO"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/btnInit"
android:layout_alignBottom="@+id/btnInit"
android:layout_alignLeft="@+id/textView1"
android:text="@string/strIOState" />
<Button
android:id="@+id/btnInit"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="@+id/txtInfo"
android:layout_marginBottom="29dp"
android:layout_marginLeft="48dp"
android:layout_toRightOf="@+id/btnDiscover"
android:text="@string/strInit" />
</RelativeLayout>
当我运行我的程序并插入我的设备时,它会询问我是否允许连接,然后我说“Ok”。然后我点击发现,它告诉我制造商是“Dajac Inc.”。产品为“EIO1000”,序列号为“0000004B”。
祝你好运;你可以给我荣誉,但只有站在别人的肩膀上(我自己的汗水很多)我才能看到这么远。转发过去!-大卫