如何在Android Studio中通过蓝牙配对的2台设备之间发送数据？

Question

I'm still new to Android studio and I'm having a lot of trouble with Bluetooth, I'm currently making an app where I need to send data between devices. I'm letting the phone's default Bluetooth setup do the pairing but now I need to know how to send the data, I know I need to use input and output streams but I don't know exactly how.

And yes I have searched all over Google, I've followed a lot of Bluetooth tutorials but none of them seem to really explain how to send data from one device to another.

Thanks in advance.

Answer 1

After you establish a secure/insecure connection via bluetooth the rest is just socket programming simply. That is lets think about sending a text. We convert the text to byte and send that by Java OutputStream. In the same manner for the data received we can get it by InputStream.

But remember you need to maintain bunch of code and thread/handler to maintain state and others. Though the basic thing is simply socket programming over Bluetooth socket using the Bluetooth adapter. Have a look at the below repository in github. This creates a chatroom over bluetooth. ie it sends and receives string data

https://github.com/zahansafallwa/Android-bluetooth-chat-with-emoji/tree/master/app/src/main/java/com/zahan/safallwa/donttalk

Specially have a look at the BluetoothChatService class. That contains codes related to sending data. BluetoothChatService

Edit:

As per your comment lets think that your devices are paired and also connected. Now you only need to send the text. Declare a outputstream

private final OutputStream mmOutStream;

Suppose you have a string. We convert it to byte. Then get our socket outputstream and send data by write() method

String message="this is test data";
byte[] send = message.getBytes();
mmOutStream = socket.getOutputStream(); // here socket is the bluetooth socket you establish
mmOutStream.write(send);//this is what sends the message

Remember:

Edited code is for your understanding only. It is prescribed to use separate thread for sending data.