如何在传输数据之前知道蓝牙设备是否仍连接到笔记本电脑?我使用blue-cove库编写了一个Java程序来发现并通过笔记本电脑传输数据。在第一次传输数据后,如何检查设备在下一次传输数据之前是否仍连接到笔记本电脑?我看到了一个类似的问题。但是他们问的是如何检查连接到Android的蓝牙设备状态。
deviceDiscovered()
和inquiryCompleted()
将被执行。inquiryCompleted
方法中收到通知,并且需要在以下代码行中处理它:try {
synchronized(lock){
lock.wait();
}
}
catch (InterruptedException e) {
e.printStackTrace();
}
InterruptedException
中,您可以处理错误。package bt;
import java.io.OutputStream;
import java.util.ArrayList;
import javax.bluetooth.DataElement;
import javax.bluetooth.DeviceClass;
import javax.bluetooth.DiscoveryAgent;
import javax.bluetooth.DiscoveryListener;
import javax.bluetooth.LocalDevice;
import javax.bluetooth.RemoteDevice;
import javax.bluetooth.ServiceRecord;
import javax.bluetooth.UUID;
import javax.microedition.io.Connector;
import javax.obex.ClientSession;
import javax.obex.HeaderSet;
import javax.obex.Operation;
import javax.obex.ResponseCodes;
import bt.BTListener.MyDeviceListenerFilter;
public class MyDiscoveryListener implements DiscoveryListener{
private static Object lock=new Object();
public ArrayList<RemoteDevice> devices;
public MyDiscoveryListener() {
devices = new ArrayList<RemoteDevice>();
}
public static void main(String[] args) {
MyDiscoveryListener listener = new MyDiscoveryListener();
try{
LocalDevice localDevice = LocalDevice.getLocalDevice();
DiscoveryAgent agent = localDevice.getDiscoveryAgent();
agent.startInquiry(DiscoveryAgent.GIAC, listener);
try {
synchronized(lock){
lock.wait();
}
}
catch (InterruptedException e) {
e.printStackTrace();
return;
}
System.out.println("Device Inquiry Completed. ");
UUID[] uuidSet = new UUID[1];
uuidSet[0]=new UUID(0x1105); //OBEX Object Push service
int[] attrIDs = new int[] {
0x0100 // Service name
};
for (RemoteDevice device : listener.devices) {
agent.searchServices(
attrIDs,uuidSet,device,listener);
try {
synchronized(lock){
lock.wait();
}
}
catch (InterruptedException e) {
e.printStackTrace();
return;
}
System.out.println("Service search finished.");
}
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
public void deviceDiscovered(RemoteDevice btDevice, DeviceClass arg1) {
String name;
try {
name = btDevice.getFriendlyName(false);
} catch (Exception e) {
name = btDevice.getBluetoothAddress();
}
devices.add(btDevice);
System.out.println("device found: " + name);
}
@Override
public void inquiryCompleted(int arg0) {
synchronized(lock){
lock.notify();
}
}
@Override
public void serviceSearchCompleted(int arg0, int arg1) {
synchronized (lock) {
lock.notify();
}
}
@Override
public void servicesDiscovered(int transID, ServiceRecord[] servRecord) {
for (int i = 0; i < servRecord.length; i++) {
String url = servRecord[i].getConnectionURL(ServiceRecord.NOAUTHENTICATE_NOENCRYPT, false);
if (url == null) {
continue;
}
DataElement serviceName = servRecord[i].getAttributeValue(0x0100);
if (serviceName != null) {
System.out.println("service " + serviceName.getValue() + " found " + url);
if(serviceName.getValue().equals("OBEX Object Push")){
sendMessageToDevice(url);
}
} else {
System.out.println("service found " + url);
}
}
}
private static void sendMessageToDevice(String serverURL){
try{
System.out.println("Connecting to " + serverURL);
ClientSession clientSession = (ClientSession) Connector.open(serverURL);
HeaderSet hsConnectReply = clientSession.connect(null);
if (hsConnectReply.getResponseCode() != ResponseCodes.OBEX_HTTP_OK) {
System.out.println("Failed to connect");
return;
}
HeaderSet hsOperation = clientSession.createHeaderSet();
hsOperation.setHeader(HeaderSet.NAME, "Hello.txt");
hsOperation.setHeader(HeaderSet.TYPE, "text");
//Create PUT Operation
Operation putOperation = clientSession.put(hsOperation);
// Send some text to server
byte data[] = "Hello World !!!".getBytes("iso-8859-1");
OutputStream os = putOperation.openOutputStream();
os.write(data);
os.close();
putOperation.close();
clientSession.disconnect(null);
clientSession.close();
}
catch (Exception e) {
e.printStackTrace();
}
}
}