写一个安卓蓝牙开门程序

下面是一个简单的安卓蓝牙开门程序的示例代码：

import android.Manifest;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.UUID;

public class MainActivity extends AppCompatActivity {

    private static final int REQUEST_ENABLE_BT = 1;
    private static final int REQUEST_PERMISSION = 2;

    private BluetoothAdapter bluetoothAdapter;
    private BluetoothDevice device;
    private BluetoothSocket socket;
    private OutputStream outputStream;
    private InputStream inputStream;

    private Button connectButton;
    private Button openButton;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        connectButton = findViewById(R.id.button_connect);
        openButton = findViewById(R.id.button_open);

        bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
        if (bluetoothAdapter == null) {
            Toast.makeText(this, "设备不支持蓝牙", Toast.LENGTH_SHORT).show();
            finish();
        }

        if (!bluetoothAdapter.isEnabled()) {
            Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
            startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
        }

        connectButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (ContextCompat.checkSelfPermission(MainActivity.this,
                        Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
                    ActivityCompat.requestPermissions(MainActivity.this,
                            new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, REQUEST_PERMISSION);
                } else {
                    connectToDevice();
                }
            }
        });

        openButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                openDoor();
            }
        });
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == REQUEST_ENABLE_BT) {
            if (resultCode == RESULT_OK) {
                Toast.makeText(this, "蓝牙已启用", Toast.LENGTH_SHORT).show();
            } else if (resultCode == RESULT_CANCELED) {
                Toast.makeText(this, "蓝牙启用被取消", Toast.LENGTH_SHORT).show();
                finish();
            }
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode == REQUEST_PERMISSION) {
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                connectToDevice();
            } else {
                Toast.makeText(this, "需要位置权限才能连接蓝牙设备", Toast.LENGTH_SHORT).show();
            }
        }
    }

    private void connectToDevice() {
        device = bluetoothAdapter.getRemoteDevice("设备的MAC地址");
        UUID uuid = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");

        try {
            socket = device.createRfcommSocketToServiceRecord(uuid);
            socket.connect();
            outputStream = socket.getOutputStream();
            inputStream = socket.getInputStream();
            Toast.makeText(this, "已连接到设备", Toast.LENGTH_SHORT).show();
        } catch (IOException e) {
            Toast.makeText(this, "无法连接到设备", Toast.LENGTH_SHORT).show();
            e.printStackTrace();
        }
    }

    private void openDoor() {
        try {
            outputStream.write("open".getBytes());
            Toast.makeText(this, "已发送开门指令", Toast.LENGTH_SHORT).show();
        } catch (IOException e) {
            Toast.makeText(this, "无法发送开门指令", Toast.LENGTH_SHORT).show();
            e.printStackTrace();
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        try {
            if (outputStream != null) {
                outputStream.close();
            }
            if (inputStream != null) {
                inputStream.close();
            }
            if (socket != null) {
                socket.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

注意替换设备的MAC地址为实际蓝牙设备的MAC地址。此示例代码连接蓝牙设备使用了位置权限，需要在 AndroidManifest.xml 文件中添加以下权限声明：

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

此外，还需要在 AndroidManifest.xml 文件中添加以下蓝牙服务声明：

<service android:name="com.android.bluetooth.BluetoothHeadset" android:enabled="true" android:exported="true"/>
<service android:name="com.android.bluetooth.BluetoothA2dp" android:enabled="true" android:exported="true"/>
<service android:name="com.android.bluetooth.BluetoothHealth" android:enabled="true" android:exported="true"/>
<service android:name="com.android.bluetooth.BluetoothHidHost" android:enabled="true" android:exported="true"/>
<service android:name="com.android.bluetooth.BluetoothHidDevice" android:enabled="true" android:exported="true"/>
<service android:name="com.android.bluetooth.BluetoothPan" android:enabled="true" android:exported="true"/>
``