蓝牙、BlueCove和树莓派

Question

我在我的RaspberryPI上使用BlueJ设置Java，使用Blueman设置蓝牙，并使用BlueCove应用编程接口。

我将示例RemoteDeviceDiscovery取自：

http://bluecove.org/bluecove/apidocs/overview-summary.html#DeviceDiscovery

当我在BlueJ中运行这个例子时，我得到：

“等待设备查询完成...设备查询已完成！找到0个设备”，当我从终端窗口运行时：

pi@raspberrypi ~/java/bluetooth_jar $ /usr/lib/jvm/jdk-8-oracle-arm-vfp-hflt/jre/bin/java -jar bluetooth_jar.jar

我得到了：

“BlueCove版本2.1.1- bluez BluetoothStateException上的快照异常: javax.bluetooth.BluetoothStateException:蓝牙设备未就绪。1操作不允许BlueCove堆栈关闭已完成”

为什么在使用BlueJ时没有抛出异常，我不明白，但是从命令行看，它似乎无法检测到附近的设备，因为设备还没有准备好。然而，我无法理解这个错误信息，因为我可以使用Blueman Manager将文件发送到附近的安卓平板电脑和Win7笔记本电脑。

import java.io.IOException;

导入java.util.ArrayList；导入javax.Bluetooth。*；

/** *最小设备发现示例。*/公共类RemoteDeviceDiscovery {

protected ArrayList<RemoteDevice> devicesDiscovered = new ArrayList();
protected final Object inquiryCompletedEvent = new Object();

public RemoteDeviceDiscovery()
{
    DiscoveryListener listener = new MyDiscoveryListener();

    synchronized(inquiryCompletedEvent) {
        try
        {
            LocalDevice local = LocalDevice.getLocalDevice();
            local.setDiscoverable(DiscoveryAgent.GIAC);
            DiscoveryAgent discoveryAgent = local.getDiscoveryAgent();
            // note: GIAC: The inquiry access code for General/Unlimited Inquiry Access Code (GIAC).
            boolean startedInquiry = discoveryAgent.startInquiry(DiscoveryAgent.GIAC, listener);
            if (startedInquiry)
            {
                System.out.println("wait for device inquiry to complete...");
                inquiryCompletedEvent.wait();
                System.out.println(devicesDiscovered.size() +  " device(s) found");
            }
        }
        catch ( BluetoothStateException e)
        {
            System.out.println("BluetoothStateException exception: " + e);
        }
        catch (InterruptedException e)
        {
            System.out.println("InterruptedException exception: " + e);
        }
    }        
}

public static void main(String[] args)
{

    RemoteDeviceDiscovery rmd = new RemoteDeviceDiscovery();
}

class MyDiscoveryListener implements DiscoveryListener
{
    public MyDiscoveryListener()
    {
    }

    public void deviceDiscovered(RemoteDevice btDevice, DeviceClass cod) {
        System.out.println("Device " + btDevice.getBluetoothAddress() + " found");
        devicesDiscovered.add(btDevice);
        try {
            System.out.println("     name " + btDevice.getFriendlyName(false));
        } catch (IOException cantGetDeviceName) {
        }
    }

    public void inquiryCompleted(int discType) {
        System.out.println("Device Inquiry completed!");
        synchronized(inquiryCompletedEvent){
            inquiryCompletedEvent.notifyAll();
        }
    }

    public void serviceSearchCompleted(int transID, int respCode) {
    }

    public void servicesDiscovered(int transID, ServiceRecord[] servRecord) {
    }    
} // class MyDiscoveryListener

} //类RemoteDeviceDiscovery

Answer 1

我发现如果我用超级用户权限运行jar，那么它就会像预期的那样工作：

pi@raspberrypi ~ sudo /java/bluetooth_jar $ /usr/lib/jvm/jdk-8-oracle-arm-vfp-hflt/jre/bin/java -jar bluetooth_jar.jar

带输出：

BlueCove版本2.1.1- bluez上的快照等待设备查询完成...Device C4850852975B found name BlueCove -PC设备查询完成！1个设备发现GMSEED堆栈关闭完成

如果我以超级用户身份从命令行启动BlueJ，而不是通过桌面菜单项Menu|Programming|BlueJ；，即：

pi@raspberrypi ~$ sudo bluej

然后，示例应用程序会给出相同的输出。