我正在尝试创建一个应用程序，通过USB Serial将数据文本从Android发送到计算机并接收。我正在使用Android中的一个名为AdbTestActivity的示例来尝试连接我的设备。我能够找到设备但是当我尝试使用UsbDeviceConnection连接= mManager.openDevice（device）时打开设备;它让我回复'null'
AdbTestActivity.java
package com.android.adb;
import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.graphics.Rect;
import android.hardware.usb.UsbDevice;
import android.hardware.usb.UsbDeviceConnection;
import android.hardware.usb.UsbInterface;
import android.hardware.usb.UsbManager;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.widget.TextView;
/* Main activity for the adb test program */
public class AdbTestActivity extends Activity {
private static final String TAG = "AdbTestActivity";
private TextView mLog;
private UsbManager mManager;
private UsbDevice mDevice;
private UsbDeviceConnection mDeviceConnection;
private UsbInterface mInterface;
private AdbDevice mAdbDevice;
private static final int MESSAGE_LOG = 1;
private static final int MESSAGE_DEVICE_ONLINE = 2;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.adb);
mLog = (TextView)findViewById(R.id.log);
mManager = (UsbManager)getSystemService(Context.USB_SERVICE);
// check for existing devices
for (UsbDevice device : mManager.getDeviceList().values()) {
UsbInterface intf = findAdbInterface(device);
if (setAdbInterface(device, intf)) {
break;
}
}
// listen for new devices
IntentFilter filter = new IntentFilter();
filter.addAction(UsbManager.ACTION_USB_DEVICE_ATTACHED);
filter.addAction(UsbManager.ACTION_USB_DEVICE_DETACHED);
registerReceiver(mUsbReceiver, filter);
}
@Override
public void onDestroy() {
unregisterReceiver(mUsbReceiver);
setAdbInterface(null, null);
super.onDestroy();
}
public void log(String s) {
Message m = Message.obtain(mHandler, MESSAGE_LOG);
m.obj = s;
mHandler.sendMessage(m);
}
private void appendLog(String text) {
Rect r = new Rect();
mLog.getDrawingRect(r);
int maxLines = r.height() / mLog.getLineHeight() - 1;
text = mLog.getText() + "\n" + text;
// see how many lines we have
int index = text.lastIndexOf('\n');
int count = 0;
while (index > 0 && count <= maxLines) {
count++;
index = text.lastIndexOf('\n', index - 1);
}
// truncate to maxLines
if (index > 0) {
text = text.substring(index + 1);
}
mLog.setText(text);
}
public void deviceOnline(AdbDevice device) {
Message m = Message.obtain(mHandler, MESSAGE_DEVICE_ONLINE);
m.obj = device;
mHandler.sendMessage(m);
}
private void handleDeviceOnline(AdbDevice device) {
log("device online: " + device.getSerial());
device.openSocket("shell:exec logcat");
}
// Sets the current USB device and interface
private boolean setAdbInterface(UsbDevice device, UsbInterface intf) {
if (mDeviceConnection != null) {
if (mInterface != null) {
mDeviceConnection.releaseInterface(mInterface);
mInterface = null;
}
mDeviceConnection.close();
mDevice = null;
mDeviceConnection = null;
}
if (device != null && intf != null) {
//Here returns null connection
UsbDeviceConnection connection = mManager.openDevice(device);
if (connection != null) {
log("open succeeded");
if (connection.claimInterface(intf, false)) {
log("claim interface succeeded");
mDevice = device;
mDeviceConnection = connection;
mInterface = intf;
mAdbDevice = new AdbDevice(this, mDeviceConnection, intf);
log("call start");
mAdbDevice.start();
return true;
} else {
log("claim interface failed");
connection.close();
}
} else {
log("open failed");
}
}
if (mDeviceConnection == null && mAdbDevice != null) {
mAdbDevice.stop();
mAdbDevice = null;
}
return false;
}
// searches for an adb interface on the given USB device
static private UsbInterface findAdbInterface(UsbDevice device) {
Log.d(TAG, "findAdbInterface " + device);
int count = device.getInterfaceCount();
for (int i = 0; i < count; i++) {
UsbInterface intf = device.getInterface(i);
if (intf.getInterfaceClass() == 255 && intf.getInterfaceSubclass() == 66 &&
intf.getInterfaceProtocol() == 1) {
return intf;
}
if (intf.getInterfaceClass() == 2 && intf.getInterfaceSubclass() == 2 &&
intf.getInterfaceProtocol() == 1) {
return intf;
}
}
return null;
}
BroadcastReceiver mUsbReceiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (UsbManager.ACTION_USB_DEVICE_ATTACHED.equals(action)) {
UsbDevice device = (UsbDevice)intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
UsbInterface intf = findAdbInterface(device);
if (intf != null) {
log("Found adb interface " + intf);
setAdbInterface(device, intf);
}
} else if (UsbManager.ACTION_USB_DEVICE_DETACHED.equals(action)) {
UsbDevice device = intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
String deviceName = device.getDeviceName();
if (mDevice != null && mDevice.equals(deviceName)) {
log("adb interface removed");
setAdbInterface(null, null);
}
}
}
};
Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MESSAGE_LOG:
appendLog((String)msg.obj);
break;
case MESSAGE_DEVICE_ONLINE:
handleDeviceOnline((AdbDevice)msg.obj);
break;
}
}
};
}
我还尝试在device_filter.xml中插入我的供应商和产品，但它不起作用。
<resources>
<usb-device class="255" subclass="66" protocol="0" />
<usb-device vendor-id="5401" product-id="32" />
</resources>
清单 ...
<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" />
答案 0 :(得分：0)
您应该在允许打开USB设备之前询问，例如：
final String usbPermissionName = "com.android.example.USB_PERMISSION";
BroadcastReceiver usbPermissionReceiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
if (usbPermissionName.equals(intent.getAction())) {
UsbDevice device = intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
if(intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false)) {
synchronized (this) {
mManager.openDevice(device);
}
}
}
}
};
registerReceiver(usbPermissionReceiver, new IntentFilter(usbPermissionName));
PendingIntent permissionPendingIntent = PendingIntent.getBroadcast(instance, 0, new Intent(usbPermissionName), 0);
usbManager.requestPermission(usbDevice, permissionPendingIntent);