蓝牙连接手机，并在手机上对数据进行显示的代码实现

以下是一个简单的Android Studio代码示例，可连接到Arduino蓝牙模块并显示来自称重传感器的数据：

MainActivity.java:

import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.widget.TextView;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import java.io.IOException;
import java.io.InputStream;
import java.util.UUID;

public class MainActivity extends AppCompatActivity {

    private BluetoothAdapter mBluetoothAdapter = null;
    private BluetoothSocket mBluetoothSocket = null;
    private InputStream mInputStream = null;
    private Thread mWorkerThread = null;
    private byte[] mReadBuffer;
    private int mReadBufferPosition;

    private TextView mTextView;

    private static final UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB"); // 蓝牙串口通信UUID
    private static final String DEVICE_ADDRESS = "00:00:00:00:00:00"; // 你的Arduino蓝牙模块的MAC地址

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

        mTextView = findViewById(R.id.text_view);

        mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
        if (mBluetoothAdapter == null) {
            Toast.makeText(this, "Bluetooth is not available", Toast.LENGTH_LONG).show();
            finish();
            return;
        }

        if (!mBluetoothAdapter.isEnabled()) {
            Toast.makeText(this, "Please enable your Bluetooth and re-run this program", Toast.LENGTH_LONG).show();
            finish();
            return;
        }

        BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(DEVICE_ADDRESS);

        try {
            mBluetoothSocket = device.createRfcommSocketToServiceRecord(MY_UUID);
            mBluetoothSocket.connect();
            mInputStream = mBluetoothSocket.getInputStream();

            beginListenForData();

        } catch (IOException e) {
            Toast.makeText(this, "Error connecting to device", Toast.LENGTH_LONG).show();
            finish();
            return;
        }
    }

    private void beginListenForData() {
        final Handler handler = new Handler() {
            @Override
            public void handleMessage(Message msg) {
                String weight = (String)msg.obj;
                mTextView.setText("Weight: " + weight + " g");
            }
        };

        mWorkerThread = new Thread(new Runnable() {
            public void run() {
                while (!Thread.currentThread().isInterrupted()) {
                    try {
                        int bytesAvailable = mInputStream.available();
                        if (bytesAvailable > 0) {
                            byte[] packetBytes = new byte[bytesAvailable];
                            mInputStream.read(packetBytes);
                            for (int i = 0; i < bytesAvailable; i++) {
                                byte b = packetBytes[i];
                                if (b == '\n') {
                                    byte[] encodedBytes = new byte[mReadBufferPosition];
                                    System.arraycopy(mReadBuffer, 0, encodedBytes, 0, encodedBytes.length);
                                    final String data = new String(encodedBytes, "US-ASCII");
                                    mReadBufferPosition = 0;

                                    handler.obtainMessage(1, data).sendToTarget();
                                } else {
                                    mReadBuffer[mReadBufferPosition++] = b;
                                }
                            }
                        }
                    } catch (IOException ex) {
                        Thread.currentThread().interrupt();
                    }
                }
            }
        });

        mReadBuffer = new byte[1024];
        mReadBufferPosition = 0;
        mWorkerThread.start();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();

        if (mWorkerThread != null) {
            mWorkerThread.interrupt();
        }

        try {
            mInputStream.close();
            mBluetoothSocket.close();
        } catch (IOException e) {
            // ignore
        }
    }
}

在这个示例中，我们首先检查设备是否支持蓝牙，并确保它已启用。然后，我们使用`BluetoothAdapter`对象获取到Arduino蓝牙模块的`BluetoothDevice`对象，并使用该对象创建一个`BluetoothSocket`对象。接下来，我们使用该`BluetoothSocket`对象获取输入流，并在`beginListenForData()`方法中启动一个新的线程来读取数据。在该方法中，我们使用一个`Handler`对象将读取到的数据发送到UI线程，以便在`TextView`控件中显示它。最后，在`onDestroy()`方法中，我们关闭蓝牙连接和线程，以便释放资源。

请注意，此示例仅仅是一个基础示例，实际应用中还需要进行更多的错误处理和异常处理。