Android串口如何接收数据 - 问答

要在Android设备上接收串口数据，可以使用Android提供的SerialPort类或第三方库来实现串口通信。以下是一个简单的示例代码，演示如何在Android设备上接收串口数据：

首先，添加必要的权限到AndroidManifest.xml文件中：

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />
<uses-permission android:name="android.permission.READ_PHONE_STATE" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.WRITE_SETTINGS" />

创建一个SerialPort类来处理串口通信：

public class SerialPort {
    private static final String TAG = SerialPort.class.getSimpleName();

    private FileDescriptor mFd;
    private FileInputStream mFileInputStream;
    private FileOutputStream mFileOutputStream;

    public SerialPort(File device, int baudrate, int flags) throws SecurityException, IOException {
        mFd = open(device.getAbsolutePath(), baudrate, flags);
        if (mFd == null) {
            Log.e(TAG, "native open returns null");
            throw new IOException();
        }
        mFileInputStream = new FileInputStream(mFd);
        mFileOutputStream = new FileOutputStream(mFd);
    }

    public InputStream getInputStream() {
        return mFileInputStream;
    }

    public OutputStream getOutputStream() {
        return mFileOutputStream;
    }

    private native static FileDescriptor open(String path, int baudrate, int flags);

    public native void close();

    static {
        System.loadLibrary("serial_port");
    }
}

在MainActivity中实现串口数据接收：

public class MainActivity extends AppCompatActivity {
    private SerialPort mSerialPort;
    private InputStream mInputStream;
    private TextView mTextView;

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

        mTextView = findViewById(R.id.text_view);

        try {
            mSerialPort = new SerialPort(new File("/dev/ttyUSB0"), 9600, 0);
            mInputStream = mSerialPort.getInputStream();

            new Thread(new Runnable() {
                @Override
                public void run() {
                    while (true) {
                        try {
                            byte[] buffer = new byte[1024];
                            int size = mInputStream.read(buffer);
                            if (size > 0) {
                                final String data = new String(buffer, 0, size);
                                runOnUiThread(new Runnable() {
                                    @Override
                                    public void run() {
                                        mTextView.setText(data);
                                    }
                                });
                            }
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                }
            }).start();
        } catch (SecurityException | IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (mSerialPort != null) {
            mSerialPort.close();
        }
    }
}

在上面的示例中，我们创建了一个SerialPort类来处理串口通信，并在MainActivity中实例化该类来接收串口数据。我们在一个单独的线程中读取串口数据并在UI线程中更新TextView来显示接收到的数据。最后，在Activity销毁时关闭串口连接。请注意，上面的代码仅供参考，实际项目中需要根据具体需求进行修改和优化。

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