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 <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <termios.h>
#include <errno.h>
#include <jni.h>
#include <android/log.h>

#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, "<init>", "()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);
}