Android 蓝牙 -> 服务发现失败
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Bluetooth -> service discovery failed
提问by Kaiser
I'm writing an application that is able to communicate with my PC. I have used the Bluetooth functionalities of the SDK 2.1.
我正在编写一个能够与我的 PC 通信的应用程序。我使用了 SDK 2.1 的蓝牙功能。
I can find devices, get their MAC address, create an RFCOMMsocket, but when I start the connection, I get the following error message.
我可以找到设备，获取它们的 MAC 地址，创建一个RFCOMM套接字，但是当我开始连接时，我收到以下错误消息。
Service discovery failed.
服务发现失败。
- Is it because of the UUID, which is not the same on my application and on my PC?
- How can I get the correct UUID on my PC?
- 是不是因为UUID在我的应用程序和我的 PC 上不一样？
- 如何在我的 PC 上获得正确的 UUID？
If I write a such application, is my Nexus Onethe client or the server?
如果我编写了一个这样的应用程序，我的Nexus One是客户端还是服务器？
回答by philDev
OK, I got the same problem, but I think I can answer a few of your questions. If your PC opened an SPP Port, for example, by using "sdptool add --channel=3 SP" your Android phone would be the client opening a socket and connecting with this socket to the server (your PC or any other Bluetooth device, for example, GPS, mouse, etc.).
好的，我遇到了同样的问题，但我想我可以回答你的一些问题。如果您的 PC 打开了一个 SPP 端口，例如，通过使用“sdptool add --channel=3 SP”，您的 Android 手机将成为客户端打开一个套接字并使用该套接字连接到服务器（您的 PC 或任何其他蓝牙设备，例如，GPS、鼠标等）。
You can get this information by reading the article Bluetooth, the definition of a client did I take out of this article.
您可以通过阅读文章Bluetooth来获取此信息，我从这篇文章中取出了客户端的定义。
If you are opening an SPP Port on the server (your PC, etc.) you are offering a standard service and there is a special UUID assigned to this service. This would be: 00001101-0000-1000-8000-00805F9B34FBif I'm not mistaken.
如果您在服务器（您的 PC 等）上打开 SPP 端口，则您提供的是标准服务，并且会为该服务分配一个特殊的 UUID。这将是：00001101-0000-1000-8000-00805F9B34FB如果我没有记错的话。
So I think we should get a qualified answer from an Android developer. Or ask this question on Thursday during the IRC office hours.
所以我认为我们应该从 Android 开发者那里得到一个合格的答案。或者在周四 IRC 办公时间问这个问题。
回答by Dev Perfecular
Hint: If you are connecting to a Bluetooth serial board then try using the well-known SPP UUID 00001101-0000-1000-8000-00805F9B34FB. However if you are connecting to an Android peer then please generate your own unique UUID.
提示：如果您连接到蓝牙串行板，请尝试使用众所周知的 SPP UUID 00001101-0000-1000-8000-00805F9B34FB。但是，如果您要连接到 Android 对等点，请生成您自己的唯一 UUID。
回答by Yoann
I found a way to be sure that the UUID is found on the device. On the client side, before device.createRfcommSocketToServiceRecord(uuid);add:
我找到了一种方法来确保在设备上找到 UUID。在客户端，在device.createRfcommSocketToServiceRecord(uuid);添加之前：
Process process = Runtime.getRuntime().exec("su -c 'sdptool records " + device.getAddress() + "'");
process.waitFor();
The process is frozen during 20-30 seconds, because Android is fetching services. But after, if the server is in discovery mode (if the server is an Android phone), the connection succeeds every time!
该过程在 20-30 秒内被冻结，因为 Android 正在获取服务。但是之后，如果服务器处于发现模式（如果服务器是安卓手机），则每次都连接成功！
回答by Brad Hein
Although it could be your UUID, I would also suggest you make sure the Bluetooth MAC is accurate and upper-case.
虽然它可能是您的 UUID，但我还建议您确保蓝牙 MAC 是准确的和大写的。
I would also suggest running hcidump -Xin a terminal on the Linux box, and see if you can see any two-way traffic between your Linux machine and phone throughout the process.
我还建议hcidump -X在 Linux 机器上的终端中运行，看看在整个过程中是否可以看到 Linux 机器和手机之间的双向流量。
回答by chihying
I had the same problem when reconnecting SPP after the first connect.
在第一次连接后重新连接 SPP 时，我遇到了同样的问题。
This is because rfcomm channel=-1in BluetoothService.java. I added updateDeviceServiceChannelCache()to the end of fetchRemoteUuids(), and then it worked!
这是因为rfcomm channel=-1在BluetoothService.java. 我添加updateDeviceServiceChannelCache()到 的末尾fetchRemoteUuids()，然后它起作用了！
回答by AbdiT
This thing happens mostly to HTC. I faced the same problem. If you first connected successfully but fail afterwards, just restart the phone and the service that failed will restart in doing so.
这件事主要发生在 HTC 身上。我遇到了同样的问题。如果您第一次连接成功但后来失败，只需重新启动手机，失败的服务就会重新启动。
