串口开发
串口开发
编译so文件和项目配置
-
google串口api下载https://github.com/cepr/android-serialport-api
-
修改android-serialport-api-master\android-serialport-api-master\android-serialport-api\project\jni目录下的Android.mk、Application.mk和SerialPort.c文件
-
Android.mk修改解决libserial_port.so: has text relocations异常
#当前文件夹
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
#目标版本
TARGET_PLATFORM := android-29
#要生成的module
LOCAL_MODULE := serial_port
LOCAL_SRC_FILES := SerialPort.c
LOCAL_LDLIBS := -llog
#加上此句
LOCAL_LDFLAGS += -fPIC
include $(BUILD_SHARED_LIBRARY)
原因在于加载的so库需要重定位, Android 6.0及更高版本已明文禁止此种情形发生。在Android 6.0之前，text reloactions的问题，会在编译的过程中，作为warning报出来；在Android 6.0以上版本，升级为error了。
- Application.mk修改
APP_ABI := armeabi-v7a
- SerialPort.c修改解决java.lang.UnsatisfiedLinkError: No implementation found for java.io.FileDescriptor com.example.serialport.SerialPort.open(java.lang.String, int, int) (tried Java_com_example_serialport_SerialPort_open and Java_com_example_serialport_SerialPort_open__Ljava_lang_String_2II)异常
#include <termios.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <jni.h>
#include "SerialPort.h"
#include "android/log.h"
static const char *TAG="serial_port";
#define LOGI(fmt, args...) __android_log_print(ANDROID_LOG_INFO, TAG, fmt, ##args)
#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;
}
}
// 此处修改成对应的java包名com.example.serialport
JNIEXPORT jobject JNICALL Java_com_example_serialport_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 */
LOGE("Invalid baudrate");
return NULL;
}
}
/* Opening device */
{
jboolean iscopy;
const char *path_utf = (*env)->GetStringUTFChars(env, path, &iscopy);
LOGD("Opening serial port %s with flags 0x%x", path_utf, O_RDWR | flags);
fd = open(path_utf, O_RDWR | flags);
LOGD("open() fd = %d", fd);
(*env)->ReleaseStringUTFChars(env, path, path_utf);
if (fd == -1)
{
/* Throw an exception */
LOGE("Cannot open port");
/* TODO: throw an exception */
return NULL;
}
}
/* Configure device */
{
struct termios cfg;
LOGD("Configuring serial port");
if (tcgetattr(fd, &cfg))
{
LOGE("tcgetattr() failed");
close(fd);
/* TODO: throw an exception */
return NULL;
}
cfmakeraw(&cfg);
cfsetispeed(&cfg, speed);
cfsetospeed(&cfg, speed);
if (tcsetattr(fd, TCSANOW, &cfg))
{
LOGE("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;
}
// 此处修改成对应的java包名com.example.serialport
JNIEXPORT void JNICALL Java_com_example_serialport_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);
LOGD("close(fd = %d)", descriptor);
close(descriptor);
}
- 在jni目录下执行ndk-build命令生成新的so文件
- 添加到项目中
- gradle中添加引用
//这里是配置JNI的引用地址，也就是引用.so文件
sourceSets {
main {
jniLibs.srcDirs = ['libs']
}
}
ndk {
abiFilters 'armeabi-v7a'
}
代码
- SerialPort.java
package com.example.serialport;
import android.util.Log;
import java.io.File;
import java.io.FileDescriptor;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
/**
* Google官方代码
* 此类的作用为，JNI的调用，用来加载.so文件的
* 获取串口输入输出流
*/
public class SerialPort {
private static final String TAG = "SerialPort";
private FileDescriptor mFd; // 文件描述
private FileInputStream mFileInputStream;
private FileOutputStream mFileOutputStream;
/**
* @param device 要操作的文件对象
* @param baudrate 波特率
* @param flags 文件操作的标志
* @throws SecurityException
* @throws IOException
*/
public SerialPort(File device, int baudrate, int flags)
throws SecurityException, IOException {
// 检查权限
if (!device.canRead() || !device.canWrite()) {
try {
// 如果丢失权限，就再获取权限
Process su;
su = Runtime.getRuntime().exec("/system/xbin/su");
String cmd = "root chmod 666 " + device.getAbsolutePath() + "\n"
+ "exit\n";
// 写命令
su.getOutputStream().write(cmd.getBytes());
if ((su.waitFor() != 0) || !device.canRead()
|| !device.canWrite()) {
throw new SecurityException();
}
} catch (Exception e) {
e.printStackTrace();
throw new SecurityException();
}
}
System.out.println(device.getAbsolutePath() + "==============================");
// 打开设备，这里面调用jni 的open方法，开启串口，传入物理地址、波特率、flags值
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);
}
// 获取串口的输入流
public InputStream getInputStream() {
return mFileInputStream;
}
// 获取串口的输出流
public OutputStream getOutputStream() {
return mFileOutputStream;
}
/**
* 打开串口设备的方法
*
* @param path 设备的绝对路径
* @param baudrate 波特率
* @param flags 标志
* @return
*/
// JNI调用，开启串口
private native static FileDescriptor open(String path, int baudrate, int flags);
// 关闭串口
public native void close();
static {
// 加载库文件.so文件
System.loadLibrary("serial_port");
}
}
- SerialController.java
package com.example.serialport;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
public class SerialController {
private ExecutorService mThreadPoolExecutor = Executors.newCachedThreadPool();
private InputStream inputStream;
private OutputStream outputStream;
private boolean isOpened = false;
private OnSerialListener mOnSerialListener;
/**
* 获取所有串口路径
*
* @return 串口路径集合
*/
public List<String> getAllSerialPortPath() {
SerialPortFinder mSerialPortFinder = new SerialPortFinder();
String[] deviceArr = mSerialPortFinder.getAllDevicesPath();
return new ArrayList<>(Arrays.asList(deviceArr));
}
/**
* 打开串口
*
* @param serialPath 串口地址
* @param baudRate 波特率
* @param flags 标志位
* O_RDONLY 以只读方式打开文件O_WRONLY 以只写方式打开文件O_RDWR 以可读写方式打开文件
*/
public void openSerialPort(String serialPath, int baudRate, int flags) {
try {
SerialPort serialPort = new SerialPort(new File(serialPath), baudRate, flags);
inputStream = serialPort.getInputStream();
outputStream = serialPort.getOutputStream();
isOpened = true;
if (mOnSerialListener != null) {
mOnSerialListener.onSerialOpenSuccess();
}
mThreadPoolExecutor.execute(new ReceiveDataThread());
} catch (Exception e) {
if (mOnSerialListener != null) {
mOnSerialListener.onSerialOpenException(e);
}
}
}
/**
* 关闭串口
*/
public void closeSerialPort() {
try {
if (inputStream != null) {
inputStream.close();
}
if (outputStream != null) {
outputStream.close();
}
isOpened = false;
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* 发送串口数据
*
* @param bytes 发送数据
*/
public void sendSerialPort(byte[] bytes) {
if (!isOpened) {
return;
}
try {
if (outputStream != null) {
outputStream.write(bytes);
outputStream.flush();
}
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* 返回串口是否开启
*
* @return 是否开启
*/
public boolean isOpened() {
return isOpened;
}
/**
* 串口返回数据内容读取
*/
private class ReceiveDataThread extends Thread {
@Override
public void run() {
super.run();
while (isOpened) {
if (inputStream != null) {
byte[] readData = new byte[1024];
try {
int size = inputStream.read(readData);
if (size > 0) {
if (mOnSerialListener != null) {
mOnSerialListener.onReceivedData(readData, size);
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
}
/**
* 设置串口监听
*
* @param onSerialListener 串口监听
*/
public void setOnSerialListener(OnSerialListener onSerialListener) {
this.mOnSerialListener = onSerialListener;
}
/**
* 串口监听
*/
public interface OnSerialListener {
/**
* 串口数据返回
*/
void onReceivedData(byte[] data, int size);
/**
* 串口打开成功
*/
void onSerialOpenSuccess();
/**
* 串口打开异常
*/
void onSerialOpenException(Exception e);
}
}
- 测试类SerialPortUtil.java
package com.example.serialport;
import android.util.Log;
import java.nio.charset.StandardCharsets;
import java.util.List;
public class SerialPortUtil {
private static final String TAG = "wmj";
private SerialController serialController;
public void fun() {
// 获取串口
serialController = new SerialController();
List<String> serialPortPaths = serialController.getAllSerialPortPath();
// 没有/dev/ttyHS1串口就返回
if (!serialPortPaths.contains("/dev/ttyHS1")) return;
// 打开串口 参数三是读写方式：1：O_RDONLY以只读方式打开文件 2：O_WRONLY以只写方式打开文件 3：O_RDWR以可读写方式打开文件
serialController.openSerialPort("/dev/ttyHS1", 9600, 2);
Log.d(TAG, "端口开关状态" + serialController.isOpened());
// 设置监听
serialController.setOnSerialListener(new SerialController.OnSerialListener() {
@Override
public void onReceivedData(byte[] data, int size) {
// 取data中size大小的数组
String s = new String(data, 0, size, StandardCharsets.UTF_8);
Log.d(TAG, "onReceivedData: " + s);
}
@Override
public void onSerialOpenSuccess() {
Log.d(TAG, "onSerialOpenSuccess: ");
}
@Override
public void onSerialOpenException(Exception e) {
Log.d(TAG, "onSerialOpenException: " + e);
}
});
// 发送数据
serialController.sendSerialPort("def哈哈".getBytes(StandardCharsets.UTF_8));
/* serialController.closeSerialPort();
Log.d(TAG, "端口开关状态" + serialController.isOpened());*/
}
}
