Android 扫码器串口通讯

最进接串口扫码器，参考 github上开源的串口通讯库https://github.com/cepr/android-serialport-api实现扫码器通讯。

1.集成

Android Studio使用 cmake编译，将SerialPort.c/SerialPort.h两个文件拷贝到 cpp 文件夹下，SerialPort.java拷贝到 android.serialport包下，记得包名要和SerialPort.h中的方法名中的包名一直。了解NDK开发的你懂得。

CMakeLists.txt

# Sets the minimum version of CMake required to build your native library.
# This ensures that a certain set of CMake features is available to
# your build.

cmake_minimum_required(VERSION 3.4.1)

# Specifies a library name, specifies whether the library is STATIC or
# SHARED, and provides relative paths to the source code. You can
# define multiple libraries by adding multiple add.library() commands,
# and CMake builds them for you. When you build your app, Gradle
# automatically packages shared libraries with your APK.

add_library( # Specifies the name of the library.
        serial_port

        # Sets the library as a shared library.
        SHARED

        # Provides a relative path to your source file(s).
        src/main/cpp/SerialPort.c)

find_library( # Sets the name of the path variable.
        log-lib

        # Specifies the name of the NDK library that
        # you want CMake to locate.
        log)

# Specifies libraries CMake should link to your target library. You
# can link multiple libraries, such as libraries you define in this
# build script, prebuilt third-party libraries, or system libraries.

target_link_libraries( # Specifies the target library.
        serial_port

        # Links the target library to the log library
        # included in the NDK.
        ${log-lib})

public class SerialPort {

    private static final String TAG = "SerialPort";

    private static final String DEFAULT_SU_PATH = "/system/bin/su";

    private static String sSuPath = DEFAULT_SU_PATH;

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

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

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

        /* Check access permission */
        if (!device.canRead() || !device.canWrite()) {
            try {
                /* Missing read/write permission, trying to chmod the file */
                Process su;
                su = Runtime.getRuntime().exec(sSuPath);
                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 SerialPort(String devicePath, int baudrate, int flags)
            throws SecurityException, IOException {
        this(new File(devicePath), baudrate, flags);
    }

    public SerialPort(File device, int baudrate) throws SecurityException, IOException {
        this(device, baudrate, 0);
    }

    public SerialPort(String devicePath, int baudrate) throws SecurityException, IOException {
        this(new File(devicePath), baudrate, 0);
    }

    /**
     * Set the su binary path, the default su binary path is {@link #DEFAULT_SU_PATH}
     *
     * @param suPath su binary path
     */
    public static void setSuPath(String suPath) {
        if (suPath == null) {
            return;
        }
        sSuPath = suPath;
    }

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

    // Getters and setters
    public InputStream getInputStream() {
        return mFileInputStream;
    }

    public OutputStream getOutputStream() {
        return mFileOutputStream;
    }

    public native void close();
}

2.使用

public SerialPort getSerialPort()
            throws SecurityException, IOException, InvalidParameterException {
        if (mSerialPort == null) {
            //串口：/dev/ttyS4，波特率：115200
            mSerialPort = new SerialPort(new File("/dev/ttyS4"), 115200);
        }
        return mSerialPort;
    }
    public void closeSerialPort() {
        if (mSerialPort != null) {
            mSerialPort.close();
            mSerialPort = null;
        }
    }

private void openSerialPort() {
        try {
            mSerialPort =getSerialPort();
            mInputStream = mSerialPort.getInputStream();
            mReadThread = new ReadThread();
            mReadThread.start();
        } catch (SecurityException e) {
            e.printStackTrace();
            ToastCompat.makeText(this, R.string.error_security, Toast.LENGTH_SHORT).show();
        } catch (IOException e) {
            e.printStackTrace();
            ToastCompat.makeText(this, R.string.error_unknown, Toast.LENGTH_SHORT).show();
        } catch (InvalidParameterException e) {
            e.printStackTrace();
            ToastCompat.makeText(this, R.string.error_configuration, Toast.LENGTH_SHORT).show();
        }
    }

private class ReadThread extends Thread {

        public ReadThread() {
        }

        @Override
        public void run() {
            super.run();
            while (!isInterrupted()) {
                int size;
                try {
                    byte[] buffer = new byte[64];
                    if (mInputStream == null) return;
                    size = mInputStream.read(buffer);
                    if (size > 0) {
                        String goodsCode = new String(buffer, 0, size);
                        EventBus.getDefault().post(new GoodsMsgEvent(goodsCode));
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                    return;
                }
            }
        }
    }