区分 "out of range" 或 "in range, but no listening server socket"？（蓝牙）

Question

问题

我如何区分无法与远程 Android 设备建立蓝牙连接，因为：

场景 1：远程设备超出范围，或者其蓝牙被禁用。
场景2：远程设备在范围内，但远程设备上没有服务器套接字来接受我的连接。

我试过的

我无法区分连接时抛出的异常，因为它在两种情况下抛出相同的异常：
```
java.io.IOException: read failed, socket might closed or timeout, read ret -1
```
我无法使用fetchUuidsWithSdp()检查远程设备是否支持我的 UUID，因为它在任何一种情况下的行为方式都相同。 .according to the documentation:

This API is asynchronous and {@link #ACTION_UUID} intent is sent, with the UUIDs supported by the remote end. If there is an error in getting the SDP records or if the process takes a long time, {@link #ACTION_UUID} intent is sent with the UUIDs that is currently present in the cache...

根据 this SO thread，它的行为似乎也有点不可预测。
最后，我不想使用sdpSearch来区分两者，因为那是在API中添加的23，我希望能撑到API 19.

Answer 1

您可以通过尝试连接到通常在 Android 设备上可用的标准 UUID 来确定设备是否在范围内。如果呼叫连接：

失败，则远程设备超出范围或蓝牙被禁用。
成功，则远程设备在范围内，您应该关闭连接，然后尝试连接到您应用的 UUID...如果失败，则没有侦听套接字...如果成功，则一切都很好。

示例代码：

public BluetoothSocket connect(BluetoothDevice remoteDevice) throws IOException
{
    OPP_UUID = UUID.fromString("00001105-0000-1000-8000-00805f9b34fb");

    // check if remote device is in range...throw exception if out of range
    try
    {
        BluetoothSocket socket = remoteDevice
            .createRfcommSocketToServiceRecord(OPP_UUID);
        socket.connect();
        socket.close();
    }
    catch(IOException ex)
    {
        throw new IOException("out of range",ex);
    }

    // try to connect to service on remote device...throw exception if UUID
    // is not available
    try
    {
        BluetoothSocket socket = remoteDevice
            .createRfcommSocketToServiceRecord(MY_UUID);
        socket.connect();
        return socket;
    }
    catch(IOException ex)
    {
        throw new IOException("no listening server socket",ex);
    }
}

我使用 BluetoothDevice.getUuids() 在我的 Android 设备之一上获取可用的 UUID。它给了我这个列表：

0000110a-0000-1000-8000-00805f9b34fb - Advanced Audio Distribution Profile (0x110a)
00001105-0000-1000-8000-00805f9b34fb - Object Push Profile (0x1105) // least invasive one...it seems
00001115-0000-1000-8000-00805f9b34fb - Personal Area Networking Profile (0x1115)
0000112f-0000-1000-8000-00805f9b34fb - Phonebook Access (0x112f) // this works!
00001112-0000-1000-8000-00805f9b34fb - Headset - Audio Gateway (0x1112)
0000111f-0000-1000-8000-00805f9b34fb - Handsfree Audio Gateway (0x111f)
00001132-0000-1000-8000-00805f9b34fb - Message Access Profile (0x1132) // this works too!
00000000-0000-1000-8000-00805f9b34fb - Base UUID (0x0000) // couldn't get this to work :(

Standard UUIDs from Bluetooth spec.

区分 "out of range" 或 "in range, but no listening server socket"？（蓝牙）

Differentiate between "out of range" or "in range, but no listening server socket"? (Bluetooth)

java

sockets

android

bluetooth

android-bluetooth

问题

我试过的

区分 "out of range" 或 "in range, but no listening server socket"？ （蓝牙）

Differentiate between "out of range" or "in range, but no listening server socket"? (Bluetooth)

java

sockets

android

bluetooth

android-bluetooth

问题

我试过的

区分 "out of range" 或 "in range, but no listening server socket"？（蓝牙）