Android串口通信实例分析【附源码】

Android 串口通信实例分析，用的时开源的android-serialport-api

这个是用android ndk实现的串口通信，我把他做了一个简化，适合于一般的程序的串口通信移植，欢迎拍砖～～～～～～～～～

先说jni接口吧，原本文件太多，其实只需要SerialPort.c和Android.mk就可以实现

Serialport.c

#include
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#define LOGI(...) ((void)__android_log_print(ANDROID_LOG_INFO, "", __VA_ARGS__))//在logcat上打印信息用
//#define LOGD(fmt, args...) __android_log_print(ANDROID_LOG_DEBUG, TAG, fmt, ##args)
//#define LOGE(fmt, args...) __android_log_print(ANDROID_LOG_ERROR, TAG, fmt, ##args)

static speed_t getBaudrate(jint baudrate)
{
    switch(baudrate) {
    case 0: return B0;
    case 50: return B50;
    case 75: return B75;
    case 110: return B110;
    case 134: return B134;
    case 150: return B150;
    case 200: return B200;
    case 300: return B300;
    case 600: return B600;
    case 1200: return B1200;
    case 1800: return B1800;
    case 2400: return B2400;
    case 4800: return B4800;
    case 9600: return B9600;
    case 19200: return B19200;
    case 38400: return B38400;
    case 57600: return B57600;
    case 115200: return B115200;
    case 230400: return B230400;
    case 460800: return B460800;
    case 500000: return B500000;
    case 576000: return B576000;
    case 921600: return B921600;
    case 1000000: return B1000000;
    case 1152000: return B1152000;
    case 1500000: return B1500000;
    case 2000000: return B2000000;
    case 2500000: return B2500000;
    case 3000000: return B3000000;
    case 3500000: return B3500000;
    case 4000000: return B4000000;
    default: return -1;
    }
}

/*
 * Class:     com.huangcheng.serial.SerialPort
 * Method:    open
 * Signature: (Ljava/lang/String;II)Ljava/io/FileDescriptor;
 *
 * 用于打开串口，配置串口参数，包括的参数有path(需要打开的串口设备文件路径)，baudrate(波特率),flags(打开串口的参数，如O_NONBLOCK之类的，可以随不同情况设置)
 * 其串口数据的读取是用FileDescriptor来实现的
 *
 */
JNIEXPORT jobject JNICALL Java_com_huangcheng_serial_SerialPort_open
  (JNIEnv *env, jclass thiz, jstring path, jint baudrate, jint flags)
{
    int fd;
    speed_t speed;
    jobject mFileDescriptor;

    /* Check arguments */
    {
        speed = getBaudrate(baudrate);
        if (speed == -1) {
            /* TODO: throw an exception */
            LOGI("Invalid baudrate");
            return NULL;
        }
    }

    /* Opening device */
    {
        jboolean iscopy;
        const char *path_utf = (*env)->GetStringUTFChars(env, path, &iscopy);
        LOGI("Opening serial port %s with flags 0x%x", path_utf, O_RDWR | flags);
        fd = open(path_utf, O_RDWR | flags);
        LOGI("open() fd = %d", fd);
        (*env)->ReleaseStringUTFChars(env, path, path_utf);
        if (fd == -1)
        {
            /* Throw an exception */
            LOGI("Cannot open port");
            /* TODO: throw an exception */
            return NULL;
        }
    }

    /* Configure device */
    {
        struct termios cfg;
        LOGI("Configuring serial port");
        if (tcgetattr(fd, &cfg))
        {
            LOGI("tcgetattr() failed");
            close(fd);
            /* TODO: throw an exception */
            return NULL;
        }

        cfmakeraw(&cfg);
        cfsetispeed(&cfg, speed);
        cfsetospeed(&cfg, speed);

        if (tcsetattr(fd, TCSANOW, &cfg))
        {
            LOGI("tcsetattr() failed");
            close(fd);
            /* TODO: throw an exception */
            return NULL;
        }
    }

    /* Create a corresponding file descriptor */
    {
        jclass cFileDescriptor = (*env)->FindClass(env, "java/io/FileDescriptor");
        jmethodID iFileDescriptor = (*env)->GetMethodID(env, cFileDescriptor, "", "()V");
        jfieldID descriptorID = (*env)->GetFieldID(env, cFileDescriptor, "descriptor", "I");
        mFileDescriptor = (*env)->NewObject(env, cFileDescriptor, iFileDescriptor);
        (*env)->SetIntField(env, mFileDescriptor, descriptorID, (jint)fd);
    }

    return mFileDescriptor;
}

/*
 * Class:     com.huangcheng.serial.SerialPort
 * Method:    close
 * Signature: ()V
 *
 * 用于串口关闭
 */
JNIEXPORT void JNICALL Java_com_huangcheng_serial_SerialPort_close
  (JNIEnv *env, jobject thiz)
{
    jclass SerialPortClass = (*env)->GetObjectClass(env, thiz);
    jclass FileDescriptorClass = (*env)->FindClass(env, "java/io/FileDescriptor");

    jfieldID mFdID = (*env)->GetFieldID(env, SerialPortClass, "mFd", "Ljava/io/FileDescriptor;");
    jfieldID descriptorID = (*env)->GetFieldID(env, FileDescriptorClass, "descriptor", "I");

    jobject mFd = (*env)->GetObjectField(env, thiz, mFdID);
    jint descriptor = (*env)->GetIntField(env, mFd, descriptorID);

    LOGI("close(fd = %d)", descriptor);
    close(descriptor);
}