目前物联网已慢慢普及，NDK开发也慢慢普及。
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今天结合自己在项目中的串口的使用说明一下Android串口通信的使用和常见问题
1 、SerialPort.c
/*
* Copyright 2009-2011 Cedric Priscal
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include
#include
#include
#include
#include
#include
#include
#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;
}
}
/*
* Class: android_serialport_SerialPort
* Method: open
* Signature: (Ljava/lang/String;II)Ljava/io/FileDescriptor;
*/
JNIEXPORT jobject JNICALL Java_android_1serialport_1api_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, "", "()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: cedric_serial_SerialPort
* Method: close
* Signature: ()V
*/
JNIEXPORT void JNICALL Java_android_1serialport_1api_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);
}
注意 ： const char kClassName = "com/jerome/serialport/SerialPort";为你Java层与jni对应得包名；
2、SerialPort.h
/* DO NOT EDIT THIS FILE - it is machine generated */
#include
/* Header for class android_serialport_api_SerialPort */
#ifndef _Included_android_serialport_api_SerialPort
#define _Included_android_serialport_api_SerialPort
#ifdef __cplusplus
extern "C" {
#endif
/*
* Class: android_serialport_api_SerialPort
* Method: open
* Signature: (Ljava/lang/String;II)Ljava/io/FileDescriptor;
*/
JNIEXPORT jobject JNICALL Java_android_1serialport_1api_SerialPort_open
(JNIEnv *, jclass, jstring, jint, jint);
/*
* Class: android_serialport_api_SerialPort
* Method: close
* Signature: ()V
*/
JNIEXPORT void JNICALL Java_android_1serialport_1api_SerialPort_close
(JNIEnv *, jobject);
#ifdef __cplusplus
}
#endif
#endif
3、Android.mk
#
# Copyright 2009 Cedric Priscal
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
TARGET_PLATFORM := android-3
LOCAL_MODULE := serial_port
LOCAL_SRC_FILES := SerialPort.c
LOCAL_LDLIBS := -llog
include $(BUILD_SHARED_LIBRARY)
如果要修改生成so文件的名称，请修改LOCAL_MODULE := serial_port
4、SerialPort.java
package android_serialport_api;
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;
import android_serialport_api.scanType.utils.LogUtils;
/**
* Created by v1ncent on 2017/10/23.
*/
public class SerialPort {
private static final String TAG = "SerialPort";
/*
* 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("/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);//打开串口
if (mFd == null) {
LogUtils.e("native open returns null");
throw new IOException();
}
mFileInputStream = new FileInputStream(mFd);
mFileOutputStream = new FileOutputStream(mFd);
}
// Getters and setters
public InputStream getInputStream() {
return mFileInputStream;
}
public OutputStream getOutputStream() {
return mFileOutputStream;
}
// JNI
private native static FileDescriptor open(String path, int baudrate, int flags);
public native void close();
static {
System.loadLibrary("serial_port");
}
}
5.SerialPortUtil
package android_serialport_api.scanType.base;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import android_serialport_api.SerialPort;
import android_serialport_api.scanType.utils.LogUtils;
/**
* ================================================
* 作 者：v1ncent
* 版 本：1.0.0
* 创建日期：2018/4/2
* 描 述：串口工具类
* 修订历史：
* ================================================
*/
public class SerialPortUtil {
private String TAG = SerialPortUtil.class.getSimpleName();
private SerialPort mSerialPort;//串口基类
private OutputStream mOutputStream;//输出流
private InputStream mInputStream;//输入流
private ReadThread mReadThread;//读取线程
private String path = "/dev/ttyS2";//串口名
private int baudrate = 115200;//波特率
private static SerialPortUtil portUtil;
private OnDataReceiveListener onDataReceiveListener = null;//接受回调
private boolean isStop = false;//控制线程的开关
public interface OnDataReceiveListener {
void onDataReceive(byte[] buffer, int size);
}
public void setOnDataReceiveListener(
OnDataReceiveListener dataReceiveListener) {
onDataReceiveListener = dataReceiveListener;
}
public static SerialPortUtil getInstance() {
if (null == portUtil) {
portUtil = new SerialPortUtil();
}
portUtil.onCreate();
return portUtil;
}
/**
* 初始化串口信息
*/
public void onCreate() {
try {
mSerialPort = new SerialPort(new File(path), baudrate, 0);
mOutputStream = mSerialPort.getOutputStream();
mInputStream = mSerialPort.getInputStream();
mReadThread = new ReadThread();
isStop = false;
mReadThread.start();
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 发送指令
*
* @param mBuffer
*/
public void sendBuffers(byte[] mBuffer) {
try {
mOutputStream = mSerialPort.getOutputStream();
if (mOutputStream != null) {
mOutputStream.write(mBuffer);
mOutputStream.close();
} else {
return;
}
} catch (IOException e) {
e.printStackTrace();
return;
}
}
/**
* 接受处理数据线程
*/
private class ReadThread extends Thread {
@Override
public void run() {
super.run();
while (!isStop && !isInterrupted()) {
int size;
try {
if (mInputStream == null)
return;
byte[] buffer = new byte[64];
size = mInputStream.read(buffer);
if (size > 0) {
if (null != onDataReceiveListener) {
onDataReceiveListener.onDataReceive(buffer, size);
}
}
} catch (Exception e) {
e.printStackTrace();
return;
}
}
}
}
/**
* 关闭串口
*/
public void closeSerialPort() {
LogUtils.i(TAG, "关闭串口");
isStop = true;
if (mReadThread != null) {
mReadThread.interrupt();
}
if (mSerialPort != null) {
mSerialPort.close();
}
}
}
具体使用方法
1.配置好相关的串口所需的jni,.so文件等
2.在你要使用的地方初始化SerialPortUtil，实现回调接口OnDataReceiveListener即可接受数据.
不懂的地方可以私信我。