2023-03-25 android app 用经典蓝牙socket方式数据传输实例

一、运行效果图，左边是服务端，右边是客户端。 资源下载路径

https://download.csdn.net/download/qq_37858386/87612932

 

一、服务端app代码

1、MainActivity.java

package com.hypernano.btserver;


import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;

import android.Manifest;
import android.annotation.SuppressLint;
import android.content.pm.PackageManager;
import android.graphics.Color;
import android.os.Bundle;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.List;
import java.util.Set;
import java.util.UUID;

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothServerSocket;
import android.bluetooth.BluetoothSocket;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity  {
    String TAG = "HPBTSERVERMA";
    // 获取到蓝牙适配器
    private BluetoothAdapter mBluetoothAdapter;
    // 用来保存搜索到的设备信息
    private List<String> bluetoothDevices = new ArrayList<String>();
    // ListView组件
    private ListView lvDevices;
    // ListView的字符串数组适配器
    private ArrayAdapter<String> arrayAdapter;
    // UUID，蓝牙建立链接需要的
    private final UUID MY_UUID = UUID
            .fromString("db764ac8-4b08-7f25-aafe-59d03c27bae3");
    // 为其链接创建一个名称
    private final String NAME = "Bluetooth_Socket";
    // 选中发送数据的蓝牙设备，全局变量，否则连接在方法执行完就结束了
    private BluetoothDevice selectDevice;
    // 获取到选中设备的客户端串口，全局变量，否则连接在方法执行完就结束了
    private BluetoothSocket clientSocket;
    // 获取到向设备写的输出流，全局变量，否则连接在方法执行完就结束了

    private InputStream is;// 获取到输入流
    private OutputStream os;// 获取到输出流


    // 服务端利用线程不断接受客户端信息
    private AcceptThread thread;
    private EditText m_send_data;
    private TextView m_connect_status;
    public static final int BLUETOOTH_CLIENT_CONNECT_INFO_MESSAGE = 1000;
    public static final int BLUETOOTH_SERVER_RECEIVED_DATA = 1001;
    @SuppressLint("MissingPermission")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        m_send_data = (EditText) findViewById(R.id.send_data);;
        m_connect_status = (TextView) findViewById(R.id.connect_status);

        // 获取到蓝牙默认的适配器
        mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
        // 获取到ListView组件
        lvDevices = (ListView) findViewById(R.id.lvDevices);
        // 为listview设置字符换数组适配器
        arrayAdapter = new ArrayAdapter<String>(this,
                android.R.layout.simple_list_item_1, android.R.id.text1,
                bluetoothDevices);
        // 为listView绑定适配器
        lvDevices.setAdapter(arrayAdapter);
        // 为listView设置item点击事件侦听
        Log.e(TAG,"hello");
        // 用Set集合保持已绑定的设备

        @SuppressLint("MissingPermission")
        Set<BluetoothDevice> devices = mBluetoothAdapter.getBondedDevices();
        if (devices.size() > 0) {
            for (BluetoothDevice bluetoothDevice : devices) {
                // 保存到arrayList集合中
                bluetoothDevices.add(bluetoothDevice.getName() + ":"
                        + bluetoothDevice.getAddress() + "\n");
            }
        }
        // 因为蓝牙搜索到设备和完成搜索都是通过广播来告诉其他应用的
        // 这里注册找到设备和完成搜索广播
        IntentFilter filter = new IntentFilter(
                BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
        registerReceiver(receiver, filter);
        filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
        registerReceiver(receiver, filter);

        thread = new AcceptThread();
        thread.start();

    }

    @SuppressLint("MissingPermission")
    public void onClick_Search(View view) {
        // 点击搜索周边设备，如果正在搜索，则暂停搜索
        if (mBluetoothAdapter.isDiscovering()) {
            mBluetoothAdapter.cancelDiscovery();
        }
        mBluetoothAdapter.startDiscovery();
    }

    public void onClick_send(View view)  {
        String text = m_send_data.getText().toString();
        Log.d(TAG,"onClick_send ready to send " + text);
        if (os != null) {
            try {
                os.write(text.getBytes("UTF-8"));
                Log.d(TAG,"successfully onClick_send " + text);
            } catch (IOException e) {
                e.printStackTrace();
                Log.d(TAG,"onClick_send Failed "+e.toString());
            }
        }else
            Log.d(TAG,"OutputStream os is null");

    }

    // 注册广播接收者
    private BroadcastReceiver receiver = new BroadcastReceiver() {
        @SuppressLint("MissingPermission")
        @Override
        public void onReceive(Context arg0, Intent intent) {
            // 获取到广播的action
            String action = intent.getAction();
            // 判断广播是搜索到设备还是搜索完成
            if (action.equals(BluetoothDevice.ACTION_FOUND)) {
                // 找到设备后获取其设备
                BluetoothDevice device = intent
                        .getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                // 

                if (device.getBondState() != BluetoothDevice.BOND_BONDED) {
                    // 设备没有绑定过，则将其保持到arrayList集合中
                    bluetoothDevices.add(device.getName() + ":"
                            + device.getAddress() + "\n");
                    // 更新字符串数组适配器，将内容显示在listView中
                    arrayAdapter.notifyDataSetChanged();
                }
            } else if (action
                    .equals(BluetoothAdapter.ACTION_DISCOVERY_FINISHED)) {
                Toast.makeText(MainActivity.this, "搜索完成", Toast.LENGTH_SHORT).show();
            }
        }
    };

    // 创建handler，因为我们接收是采用线程来接收的，在线程中无法操作UI，所以需要handler
    @SuppressLint("HandlerLeak")
    Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            // TODO Auto-generated method stub
            super.handleMessage(msg);
            // 通过msg传递过来的信息，吐司一下收到的信息
            Log.i(TAG,"recevied message:"+msg.obj);
            switch (msg.what){

                case BLUETOOTH_CLIENT_CONNECT_INFO_MESSAGE:
                    int status = (int) msg.arg1;
                    if(status == 0){
                        m_connect_status.setText("客户端已断开");
                        m_connect_status.setTextColor(Color.RED);}
                    else if(status == 1){
                        m_connect_status.setText("等待客户端连接");
                        m_connect_status.setTextColor(Color.GRAY);
                    }
                    else if(status == 2) {
                        m_connect_status.setText("客户端已连接");
                        m_connect_status.setTextColor(Color.GREEN);
                    }

                    Toast.makeText(MainActivity.this, (String) msg.obj, Toast.LENGTH_SHORT).show();

                    break;
                case BLUETOOTH_SERVER_RECEIVED_DATA:
                    Toast.makeText(MainActivity.this, (String) msg.obj, Toast.LENGTH_SHORT).show();
                    break;
            }

        }
    };

    // 服务端接收信息线程
    private class AcceptThread extends Thread {
        private BluetoothServerSocket serverSocket;// 服务端接口
        private BluetoothSocket socket;// 获取到客户端的接口
        //private InputStream is;// 获取到输入流
        //private OutputStream os;// 获取到输出流
        Message msg = new Message();
        @SuppressLint("MissingPermission")
        public AcceptThread() {
            try {
                // 通过UUID监听请求，然后获取到对应的服务端接口
                serverSocket = mBluetoothAdapter
                        .listenUsingRfcommWithServiceRecord(NAME, MY_UUID);
                Log.i(TAG,"listenUsingRfcommWithServiceRecord\n");

            } catch (Exception e) {

                // TODO: handle exception
            }
        }

        public void run() {
            while (true) {
            try {
                    Log.i(TAG, "accept,waiting a client... \n");

                    msg = handler.obtainMessage();
                    msg.what = BLUETOOTH_CLIENT_CONNECT_INFO_MESSAGE;
                    msg.obj = "there is a client connected";
                    msg.arg1 = 1;
                    handler.sendMessage(msg);

                    socket = serverSocket.accept();
                    msg = handler.obtainMessage();
                    msg.what = BLUETOOTH_CLIENT_CONNECT_INFO_MESSAGE;
                    msg.obj = "there is a client connected";
                    msg.arg1 = 2;
                    handler.sendMessage(msg);
                    Log.i(TAG, "there is a client connected \n");

                    // 获取到输入流
                    is = socket.getInputStream();
                    // 获取到输出流
                    os = socket.getOutputStream();
                    Log.i(TAG, "accept getInputStream getOutputStream \n");

                    while (true) {
                        byte[] buffer = new byte[128];
                        Log.i(TAG, "reading... ");
                        int count = is.read(buffer);
                        Log.i(TAG, "read count " + count);
                        os.write("OK".getBytes("UTF-8"));
                        // 创建Message类，向handler发送数据
                        //Message msg = new Message();
                        msg = handler.obtainMessage();
                        msg.what = BLUETOOTH_SERVER_RECEIVED_DATA;
                        msg.obj = new String(buffer, 0, count, "utf-8");
                        handler.sendMessage(msg);
                    }
                } catch(Exception e){
                    // TODO: handle exception
                    e.printStackTrace();
                    Log.d(TAG, "read  Thread " + e.toString());
                }
                msg = handler.obtainMessage();
                msg.what = BLUETOOTH_CLIENT_CONNECT_INFO_MESSAGE;
                msg.obj = "the client is disconnected";
                msg.arg1 = 0;
                handler.sendMessage(msg);
            }
        }
    }
}

2、activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >
    <TextView
        android:id="@+id/connect_status"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:layout_marginBottom="20dp"
        android:textStyle="bold"
        android:textSize="25dp"
        android:gravity="center_horizontal"
        android:text="当前状态" />
    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:onClick="onClick_Search"
        android:visibility="gone"
        android:text="搜索" />

    <ListView
        android:id="@+id/lvDevices"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" />


    <EditText
        android:id="@+id/send_data"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="server data" />

    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:onClick="onClick_send"
        android:text="发送" />



</LinearLayout>

3、AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">

    <application
        android:allowBackup="true"
        android:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.Btserver"
        tools:targetApi="31">
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>

            <meta-data
                android:name="android.app.lib_name"
                android:value="" />
        </activity>
    </application>

    <uses-permission android:name="android.permission.BLUETOOTH"/>
    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

</manifest>

二、客户端app代码

1、MainActivity .java

package com.hypernano.hyperbluetooth;

import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;

import android.Manifest;
import android.annotation.SuppressLint;
import android.content.pm.PackageManager;
import android.graphics.Color;
import android.os.Bundle;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.List;
import java.util.Set;
import java.util.UUID;

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothServerSocket;
import android.bluetooth.BluetoothSocket;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.text.method.ScrollingMovementMethod;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity implements OnItemClickListener {
    String TAG = "HPBMainActivity";
    // 获取到蓝牙适配器
    private BluetoothAdapter mBluetoothAdapter;
    // 用来保存搜索到的设备信息
    private List<String> bluetoothDevices = new ArrayList<String>();
    // ListView组件
    private ListView lvDevices;
    // ListView的字符串数组适配器
    private ArrayAdapter<String> arrayAdapter;
    // UUID，蓝牙建立链接需要的
    private final UUID MY_UUID = UUID
            .fromString("db764ac8-4b08-7f25-aafe-59d03c27bae3");
    // 为其链接创建一个名称
    private final String NAME = "Bluetooth_Socket";
    // 选中发送数据的蓝牙设备，全局变量，否则连接在方法执行完就结束了
    private BluetoothDevice selectDevice;
    // 获取到选中设备的客户端串口，全局变量，否则连接在方法执行完就结束了
    private BluetoothSocket clientSocket;
    // 获取到向设备写的输出流，全局变量，否则连接在方法执行完就结束了
    private OutputStream os;
    // 服务端利用线程不断接受客户端信息
    private EditText m_send_data;
    private ReadThread mReadThread;

    public static final int BLUETOOTH_CLIENT_CONNECT_INFO_MESSAGE = 1000;
    public static final int BLUETOOTH_CLIENT_RECEIVED_DATA = 1001;
    public int received_data_line = 0;

    private TextView m_connect_status , m_received_data;
    public StringBuffer sb = new StringBuffer();
    @SuppressLint("MissingPermission")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        m_send_data = (EditText) findViewById(R.id.send_data);
        m_connect_status = (TextView) findViewById(R.id.connect_status);
        m_connect_status.setText("当前状态:"+"断开");
        m_received_data = (TextView) findViewById(R.id.received_data);
        m_received_data.setMovementMethod(ScrollingMovementMethod.getInstance());
        // 获取到蓝牙默认的适配器
        mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
        // 获取到ListView组件
        lvDevices = (ListView) findViewById(R.id.lvDevices);
        // 为listview设置字符换数组适配器
        arrayAdapter = new ArrayAdapter<String>(this,
                android.R.layout.simple_list_item_1, android.R.id.text1,
                bluetoothDevices);
        // 为listView绑定适配器
        lvDevices.setAdapter(arrayAdapter);
        // 为listView设置item点击事件侦听
        lvDevices.setOnItemClickListener(this);
        // 用Set集合保持已绑定的设备

        @SuppressLint("MissingPermission")
        Set<BluetoothDevice> devices = mBluetoothAdapter.getBondedDevices();
        if (devices.size() > 0) {
            for (BluetoothDevice bluetoothDevice : devices) {
                // 保存到arrayList集合中
                bluetoothDevices.add(bluetoothDevice.getName() + ":"
                        + bluetoothDevice.getAddress() + "\n");
            }
        }
        // 因为蓝牙搜索到设备和完成搜索都是通过广播来告诉其他应用的
        // 这里注册找到设备和完成搜索广播
        IntentFilter filter = new IntentFilter(
                BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
        registerReceiver(receiver, filter);
        filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
        registerReceiver(receiver, filter);
        Log.e(TAG, "Client onCreate");
    }

    @SuppressLint("MissingPermission")
    public void onClick_Search(View view) {
        setTitle("正在扫描...");
        // 点击搜索周边设备，如果正在搜索，则暂停搜索
        if (mBluetoothAdapter.isDiscovering()) {
            mBluetoothAdapter.cancelDiscovery();
        }
        mBluetoothAdapter.startDiscovery();
    }

    public void onClick_send(View view) throws IOException {
        if (os != null) {
            try {
                String text = m_send_data.getText().toString();
                os.write(text.getBytes("UTF-8"));
                Toast.makeText(MainActivity.this, "发送成功", Toast.LENGTH_SHORT).show();
            } catch (IOException e) {
                e.printStackTrace();
                clientSocket.close();
                clientSocket = null;
                os.close();
                os = null;
                Log.e(TAG, "onClick_send "+ e.toString());
            }
        }
    }

    // 注册广播接收者
    private BroadcastReceiver receiver = new BroadcastReceiver() {
        @SuppressLint("MissingPermission")
        @Override
        public void onReceive(Context arg0, Intent intent) {
            // 获取到广播的action
            String action = intent.getAction();
            // 判断广播是搜索到设备还是搜索完成
            if (action.equals(BluetoothDevice.ACTION_FOUND)) {
                // 找到设备后获取其设备
                BluetoothDevice device = intent
                        .getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                // 判断这个设备是否是之前已经绑定过了，如果是则不需要添加，在程序初始化的时候已经添加了

                if (device.getBondState() != BluetoothDevice.BOND_BONDED) {
                    // 设备没有绑定过，则将其保持到arrayList集合中
                    bluetoothDevices.add(device.getName() + ":"
                            + device.getAddress() + "\n");
                    // 更新字符串数组适配器，将内容显示在listView中
                    arrayAdapter.notifyDataSetChanged();
                }
            } else if (action
                    .equals(BluetoothAdapter.ACTION_DISCOVERY_FINISHED)) {
                //setTitle("搜索完成");
                Toast.makeText(MainActivity.this, "搜索完成", Toast.LENGTH_SHORT).show();
            }
        }
    };

    public class ReadThread extends Thread {
        @Override
        public void run() {
            byte[] buffer = new byte[1024];
            int bytes;
            InputStream inputStream;
            Log.d(TAG, "start ReadThread");

            while (true) {
                try {
                    inputStream = clientSocket.getInputStream();
                    Log.d(TAG, "waiting to reading....");
                    if ((bytes = inputStream.read(buffer)) > 0) {
                        byte[] buf_data = new byte[bytes];
                        for (int i = 0; i < bytes; i++) {
                            buf_data[i] = buffer[i];
                        }
                        String s = new String(buf_data);
                        Message msg = new Message();
                        msg.what = BLUETOOTH_CLIENT_RECEIVED_DATA;
                        msg.obj = s;
                        handler.sendMessage(msg);
                    }
                } catch (IOException e) {
                    Message msg = new Message();
                    msg.what = BLUETOOTH_CLIENT_CONNECT_INFO_MESSAGE;
                    msg.arg1 = 0;
                    msg.obj = "Failed to connect the server," + e.toString();
                    handler.sendMessage(msg);
                    Log.d(TAG, e.toString());
                    break;
                }
            }

            if (clientSocket != null) {
                try {
                    clientSocket.close();
                    clientSocket = null;
                } catch (IOException e) {
                    Log.d("TAG", e.toString());
                }
            }
        }
    }

    // 点击listView中的设备，传送数据
    @SuppressLint("MissingPermission")
    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position,
                            long id) {
        // 获取到这个设备的信息
        String s = arrayAdapter.getItem(position);
        // 对其进行分割，获取到这个设备的地址
        String address = s.substring(s.indexOf(":") + 1).trim();
        Message msg = new Message();
        Log.d(TAG, "address:" + address);
        if (mBluetoothAdapter.isDiscovering()) {
            mBluetoothAdapter.cancelDiscovery();
        }
        // 如果选择设备为空则代表还没有选择设备
        if (selectDevice == null) {
            //通过地址获取到该设备
            selectDevice = mBluetoothAdapter.getRemoteDevice(address);
        }
              try {

                        if (clientSocket == null) {
                            // 获取到客户端接口
                            clientSocket = selectDevice
                                    .createRfcommSocketToServiceRecord(MY_UUID);
                            // 向服务端发送连接
                            //Toast.makeText(this, "connecting to the server,mac address " + address, Toast.LENGTH_SHORT).show();

                            msg = handler.obtainMessage();
                            msg.what = BLUETOOTH_CLIENT_CONNECT_INFO_MESSAGE;
                            msg.obj = "connecting to the server,mac address " + address;
                            msg.arg1 = 1;
                            handler.sendMessage(msg);

                            clientSocket.connect();
                            os = clientSocket.getOutputStream();
                            if (os != null) {
                                String text = "hello server,i am a client.";
                                os.write(text.getBytes("UTF-8"));
                            }

                            mReadThread = new ReadThread();
                            mReadThread.start();
                            Log.d(TAG, "connected to server!");
                           // Toast.makeText(this, "connected to server!", Toast.LENGTH_SHORT).show();

                            msg = handler.obtainMessage();
                            msg.what = BLUETOOTH_CLIENT_CONNECT_INFO_MESSAGE;
                            msg.obj = "connected to the server successfully!";
                            msg.arg1 = 3;
                            handler.sendMessage(msg);
                        }

                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        clientSocket = null;
                        e.printStackTrace();
                        Log.d(TAG, "failed to connect server," + e.toString());

                        msg = handler.obtainMessage();
                        msg.what = BLUETOOTH_CLIENT_CONNECT_INFO_MESSAGE;
                        msg.arg1 = 0;
                        msg.obj = "Failed to connect the server," + e.toString();
                        handler.sendMessage(msg);
                    }
    }

    void refresh_received_data(String msg)
    {
        m_received_data.append(msg);
        int offset = m_received_data.getLineCount() * m_received_data.getLineHeight();
        if(offset > m_received_data.getHeight()){
            m_received_data.scrollTo(0,offset- m_received_data.getHeight());
        }
    }

    // 创建handler，因为我们接收是采用线程来接收的，在线程中无法操作UI，所以需要handler
    @SuppressLint("HandlerLeak")
    Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            // TODO Auto-generated method stub
            super.handleMessage(msg);

            switch (msg.what){
                case BLUETOOTH_CLIENT_CONNECT_INFO_MESSAGE:
                    int sts = (int) msg.arg1;
                    if(sts == 0){
                        m_connect_status.setText("当前状态:" + "断开");
                        m_connect_status.setTextColor(Color.GRAY);
                        Toast.makeText(MainActivity.this, (String) msg.obj, Toast.LENGTH_SHORT).show();
                    }else if(sts == 1){
                        m_connect_status.setText("当前状态:" + "正在连接...");
                    }else if(sts == 3){
                        m_connect_status.setText("当前状态:"+"已经连接到服务端");
                        m_connect_status.setTextColor(Color.GREEN);
                        //sb.delete(0,sb.length());
                        received_data_line = 0;
                        m_received_data.scrollTo(0,0);
                        m_received_data.setText("\n");
                        refresh_received_data("接收到的数据：");
                    }
                    break;
                case BLUETOOTH_CLIENT_RECEIVED_DATA:
                    String str = String.format("%05d",received_data_line);
                 //   sb.append( str +":" + msg.obj+ "\n");
                    received_data_line++;
                    refresh_received_data("\n" + str +":" + msg.obj );
                    break;
                default:
                    //Toast.makeText(MainActivity.this, (String) msg.obj, Toast.LENGTH_SHORT).show();
                    break;
            }

            Log.i(TAG, "recevied message:" + msg.obj);
        }
    };

    @SuppressLint("MissingPermission")
    @Override
    public void onDestroy() {
        super.onDestroy();
        try {
            mBluetoothAdapter.cancelDiscovery();
            clientSocket.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        // mBluetoothAdapter.disable();
    }
}

2、activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/connect_status"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:layout_marginBottom="20dp"
        android:textStyle="bold"
        android:textSize="25dp"
        android:gravity="center_horizontal"
        android:text="当前状态" />

    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:onClick="onClick_Search"
        android:text="搜索" />

    <ListView
        android:id="@+id/lvDevices"
        android:layout_width="match_parent"
        android:layout_height="80dp" />

    <LinearLayout
        android:id="@+id/connect_area"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="0dp"
        android:gravity="center_horizontal"
        android:orientation="horizontal">

        <EditText
            android:id="@+id/send_data"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="3"
            android:text="I am client" />
        <Button
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:onClick="onClick_send"
            android:text="发送" />
    </LinearLayout>

    <TextView
        android:id="@+id/received_data"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:text="接收到的数据："
        android:fadeScrollbars="false"
        android:scrollbars="vertical"/>

</LinearLayout>

3、AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">

    <uses-permission android:name="android.permission.BLUETOOTH_CONNECT" />
    <uses-permission android:name="android.permission.BLUETOOTH_SCAN" />

    <application
        android:allowBackup="true"
        android:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.HyperBluetooth"
        tools:targetApi="31">
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>

            <meta-data
                android:name="android.app.lib_name"
                android:value="" />
        </activity>
    </application>
    <uses-permission android:name="android.permission.BLUETOOTH"/>
    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

</manifest>

四、代码主要参考文章

Android蓝牙搜索设备，向其发送数据并接收-刘宇_android 蓝牙数据传输_Brycen Liu的博客-CSDN博客

五、其他参考文章

用C写蓝牙通讯程序：扫描、读取、发送_#include <bluetooth/bluetooth.h> #include <bluetoo_believe209的博客-CSDN博客

Android 使用Socket实现服务器与手机客户端的长连接一：一对一聊天_12506227的技术博客_51CTO博客

android蓝牙简单开发示例教程_Android_脚本之家