GoogleSerialPort

public class SerialPort {
    private static final String TAG = "SerialPort";

    /**
     * .so 库名字。需要去掉生成时自带的lib前缀
     * */
    static {
        System.loadLibrary("serial_port");
    }

    /**
     * JNI
     * <p>
     * 必须用 native 标识JNI方法
     */
    private native static FileDescriptor open(String path, int baudRate, int flags);

    public native void close();
}

#!/bin/sh
javah -encoding utf-8 -o SerialPort.h -jni -classpath ../java com.casic.pengxh.ndk.uart.SerialPort

public class SerialPort {
    private static final String TAG = "SerialPort";

    /**
     * .so 库名字。需要去掉生成时自带的lib前缀
     * */
    static {
        System.loadLibrary("serial_port");
    }

    /**
     * JNI
     * <p>
     * 必须用 native 标识JNI方法
     */
    private native static FileDescriptor open(String path, int baudRate, int flags);

    public native void close();

    /**
     * Do not remove or rename the field mFd: it is used by native method close();
     */
    private FileDescriptor mFd;
    private final FileInputStream mFileInputStream;
    private final FileOutputStream mFileOutputStream;

    public SerialPort(File device, int baudrate, int flags) throws SecurityException, IOException {

        if (!device.canRead() || !device.canWrite()) {
            try {
                Process su;
                //路径与设备有关，具体情况需要和硬件组确定
                su = Runtime.getRuntime().exec("/system/bin/su");
                String cmd = "chmod 666 " + device.getAbsolutePath() + "\n"
                        + "exit\n";
                su.getOutputStream().write(cmd.getBytes());
                if ((su.waitFor() != 0) || !device.canRead() || !device.canWrite()) {
                    throw new SecurityException();
                }
            } catch (Exception e) {
                e.printStackTrace();
                throw new SecurityException();
            }
        }

        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;
    }
}

    defaultConfig {
    ndk {
        moduleName "serial_port"
        //"log"表示加入Android Logcat日志，需要导入 #include "android/log.h"
        ldLibs "log"
    }
}

a203@MacBook-Pro jni % ndk-build

class BaseApplication : Application() {

    private val kTag = "BaseApplication"
    private var serialPorts: ArrayList<SerialPort>? = null

    @Throws(SecurityException::class, IOException::class, InvalidParameterException::class)
    fun getSerialPorts(): ArrayList<SerialPort>? {
        serialPorts = ArrayList()
        /**
         * Open the serial port
         * */
        serialPorts?.apply {
            //串口名，波特率，停止位、校验位等，具体情况需要和硬件组确定
            add(SerialPort(File("/dev/ttysWK1"), 9600, 0))
            add(SerialPort(File("/dev/ttysWK2"), 9600, 0))
        }
        return serialPorts
    }


    fun closeSerialPort() {
        serialPorts?.forEach {
            it.close()
        }
    }

    companion object {
        private var application: BaseApplication by Delegates.notNull()

        fun get() = application
    }

    override fun onCreate() {
        super.onCreate()
        application = this
    }
}

abstract class SerialPortActivity : AppCompatActivity() {

    private val kTag = "SerialPortActivity"
    lateinit var out: OutputStream

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(initLayoutView())
        setupTopBarLayout()
        initData(savedInstanceState)
        observeRequestState()
        initEvent()

        try {
            val serialPorts = BaseApplication.get().getSerialPorts()
            //读
            lifecycleScope.launch(Dispatchers.IO) {
                serialPorts?.apply {
                    val stream = this[0].inputStream
                    while (isActive) {
                        try {
                            val buffer = ByteArray(64)
                            val size = stream.read(buffer)
                            if (size > 0) {
                                withContext(Dispatchers.Main) {
                                    onDataReceived(buffer)
                                }
                            }
                        } catch (e: IOException) {
                            e.printStackTrace()
                        }
                    }
                }
            }

            lifecycleScope.launch(Dispatchers.IO) {
                serialPorts?.apply {
                    val stream = this[1].inputStream
                    while (isActive) {
                        try {
                            val buffer = ByteArray(64)
                            val size = stream.read(buffer)
                            if (size > 0) {
                                withContext(Dispatchers.Main) {
                                    onDataReceived(buffer)
                                }
                            }
                        } catch (e: IOException) {
                            e.printStackTrace()
                        }
                    }
                }
            }

            Toast.makeText(this, "串口已打开！", Toast.LENGTH_SHORT).show()
            Log.d(kTag, "onCreate => 串口已打开！")

            //写
            serialPorts?.apply {
                out = this[0].outputStream
            }
        } catch (e: SecurityException) {
            Toast.makeText(this, "您没有串口的读写权限！", Toast.LENGTH_SHORT).show()
        } catch (e: IOException) {
            Toast.makeText(this, "因为不明原因，串口无法打开！", Toast.LENGTH_SHORT).show()
        } catch (e: InvalidParameterException) {
            Toast.makeText(this, "请检查串口！", Toast.LENGTH_SHORT).show()
        }
    }

    /**
     * 初始化xml布局
     */
    abstract fun initLayoutView(): Int

    /**
     * 特定页面定制沉浸式状态栏
     */
    abstract fun setupTopBarLayout()

    /**
     * 初始化默认数据
     */
    abstract fun initData(savedInstanceState: Bundle?)

    /**
     * 数据请求状态监听
     */
    abstract fun observeRequestState()

    /**
     * 初始化业务逻辑
     */
    abstract fun initEvent()

    /**
     * 串口读数
     * */
    abstract fun onDataReceived(buffer: ByteArray)

    override fun onDestroy() {
        BaseApplication.get().closeSerialPort()
        super.onDestroy()
    }
}