概述

在 Windows 平台下操作串口,需要调用 Win32 API CreateFileReadFileWriteFile 等,代码稍显繁琐。本类对串口的打开、配置、读写操作进行封装,提供简洁的 C++ 接口,并内置了接收线程和回调机制。

源码共 3 个文件:

文件 说明
SerialPort.h 类声明
SerialPort.cpp 完整实现
main.cpp 使用示例

头文件SerialPort.h

#pragma once
#include <windows.h>
#include <string>
#include <vector>
#include <thread>
#include <atomic>
#include <functional>
#include <mutex>
class SerialPort {
public:
SerialPort();
~SerialPort();
bool open(const std::string& portName, unsigned long baudRate);
void close();
bool isOpen() const;
std::string getLastError() const;
// 发送数据(线程安全)
bool write(const std::vector<unsigned char>& data);
bool write(const std::string& s);
// 设置接收回调
void setReceiveCallback(std::function<void(const std::vector<unsigned char>&)> cb);
private:
void receiveLoop();
HANDLE m_handle;
std::atomic<bool> m_running;
std::thread m_thread;
std::string m_lastError;
std::function<void(const std::vector<unsigned char>&)> m_callback;
std::mutex m_writeMutex;
};

设计要点

  • std::atomic<bool> m_running:跨线程共享的运行标志,比 volatile bool 更安全。
  • std::mutex m_writeMutex:写操作加锁,保证多线程并发调用 write() 时的线程安全。
  • std::function 回调:用户可通过 lambda、函数指针等灵活注册数据接收处理逻辑。
  • RAII 析构close() 在析构函数中自动调用,确保资源释放。

实现SerialPort.cpp

构造函数与析构

SerialPort::SerialPort()
: m_handle(INVALID_HANDLE_VALUE), m_running(false)
{
}
SerialPort::~SerialPort()
{
close();
}

析构调用 close(),保证对象销毁时串口一定被关闭。

错误信息辅助函数

static std::string GetLastErrorAsString(DWORD err)
{
if (err == 0) return std::string();
LPSTR messageBuffer = nullptr;
DWORD size = FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
nullptr, err, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), (LPSTR)&messageBuffer, 0, nullptr);
std::string message;
if (messageBuffer && size > 0) message.assign(messageBuffer, size);
if (messageBuffer) LocalFree(messageBuffer);
return message;
}

将 Windows API 的错误码转换为可读的字符串,供调试使用。

打开串口open()

bool SerialPort::open(const std::string& portName, unsigned long baudRate)
{
if (isOpen()) return true;
std::string fullName = portName;
if (portName.rfind("\\\\.", 0) != 0) {
fullName = "\\\\.\\" + portName;
}
m_handle = CreateFileA(fullName.c_str(),
GENERIC_READ | GENERIC_WRITE,
0, nullptr, OPEN_EXISTING, 0, nullptr);
  1. 路径格式:Windows 上超过 COM9 的串口名(如 COM10、COM\.\ PHYSICALCOM0)需要加 \\.\ 前缀。代码自动补全。
  2. 同步模式:使用同步 I/O,接收由独立线程负责,避免阻塞主线程。
    DCB dcb;
SecureZeroMemory(&dcb, sizeof(dcb));
dcb.DCBlength = sizeof(dcb);
if (!GetCommState(m_handle, &dcb)) { /* ... */ }
dcb.BaudRate = baudRate;
dcb.ByteSize = 8;
dcb.Parity = NOPARITY;
dcb.StopBits = ONESTOPBIT;
if (!SetCommState(m_handle, &dcb)) { /* ... */ }

通过 DCB 结构配置波特率、数据位、校验位、停止位,默认 8N1。

    COMMTIMEOUTS timeouts;
timeouts.ReadIntervalTimeout = 50;
timeouts.ReadTotalTimeoutMultiplier = 0;
timeouts.ReadTotalTimeoutConstant = 50;
timeouts.WriteTotalTimeoutMultiplier = 0;
timeouts.WriteTotalTimeoutConstant = 50;
SetCommTimeouts(m_handle, &timeouts);
PurgeComm(m_handle, PURGE_RXCLEAR | PURGE_TXCLEAR | PURGE_RXABORT | PURGE_TXABORT);
m_running = true;
m_thread = std::thread(&SerialPort::receiveLoop, this);
return true;
}
  • 超时设置:Read 每次最多等待 50ms,防止 ReadFile 永久阻塞。
  • 清空缓冲PurgeComm 丢弃旧数据。
  • 启动接收线程receiveLoop() 在独立线程中运行。

关闭串口close()

void SerialPort::close()
{
if (!isOpen()) return;
m_running = false;
CancelIoEx(m_handle, nullptr);   // 取消阻塞中的 IO
if (m_thread.joinable()) m_thread.join();
if (m_handle != INVALID_HANDLE_VALUE) {
CloseHandle(m_handle);
m_handle = INVALID_HANDLE_VALUE;
}
}

关键点:

  1. m_running = false 通知接收线程退出。
  2. CancelIoEx 中断 ReadFile,配合超时设置使线程尽快退出。
  3. join() 等待线程结束,避免析构时线程仍运行。
  4. 最后才 CloseHandle,保证线程已安全退出。

发送数据write()

bool SerialPort::write(const std::vector<unsigned char>& data)
{
if (!isOpen()) { m_lastError = "Port not open"; return false; }
std::lock_guard<std::mutex> lock(m_writeMutex);
DWORD bytesWritten = 0;
BOOL ok = WriteFile(m_handle, data.data(), static_cast<DWORD>(data.size()), &bytesWritten, nullptr);
if (!ok) { m_lastError = "WriteFile failed: " + GetLastErrorAsString(GetLastError()); return false; }
return bytesWritten == data.size();
}
bool SerialPort::write(const std::string& s)
{
return write(std::vector<unsigned char>(s.begin(), s.end()));
}
  • 写锁std::lock_guard 保证多线程同时调用 write() 时不会产生竞态。
  • 两个重载:一个接受字节数组,一个接受字符串,使用更方便。

接收回调setReceiveCallback()

void SerialPort::setReceiveCallback(std::function<void(const std::vector<unsigned char>&)> cb)
{
m_callback = std::move(cb);
}

使用 std::move 避免不必要的拷贝。

接收线程receiveLoop()

void SerialPort::receiveLoop()
{
const DWORD bufSize = 1024;
std::vector<unsigned char> buffer(bufSize);
while (m_running && isOpen()) {
DWORD bytesRead = 0;
BOOL ok = ReadFile(m_handle, buffer.data(), bufSize, &bytesRead, nullptr);
if (!ok) {
DWORD err = GetLastError();
if (err != ERROR_IO_PENDING && err != ERROR_TIMEOUT && err != ERROR_SUCCESS) {
m_lastError = "ReadFile failed: " + GetLastErrorAsString(err);
break;
}
}
if (bytesRead > 0) {
std::vector<unsigned char> data(buffer.begin(), buffer.begin() + bytesRead);
if (m_callback) {
try { m_callback(data); }
catch (...) { /* 忽略回调异常 */ }
}
else {
// 默认打印:可打印字符 + HEX
std::cout << "[串口接收] 字符: " << printable << "  HEX: " << ossHex.str() << std::endl;
}
}
std::this_thread::sleep_for(std::chrono::milliseconds(10));
}
}

逻辑说明:

  1. 循环读取,直到 m_running 为 false 或发生错误。
  2. ReadFile 在超时设置下最多阻塞 50ms,之后返回,即使未读到任何数据。
  3. 读到数据后:优先调用用户回调;无回调时默认打印 HEX + 可打印字符。
  4. 回调异常捕获:防止用户回调中的崩溃影响串口接收线程。
  5. 每次循环 sleep_for(10ms) 降低 CPU 占用。

完整源码

SerialPort.h

#pragma once
#include <windows.h>
#include <string>
#include <vector>
#include <thread>
#include <atomic>
#include <functional>
#include <mutex>
class SerialPort {
public:
SerialPort();
~SerialPort();
bool open(const std::string& portName, unsigned long baudRate);
void close();
bool isOpen() const;
std::string getLastError() const;
// 发送数据(线程安全)
bool write(const std::vector<unsigned char>& data);
bool write(const std::string& s);
// 设置接收回调
void setReceiveCallback(std::function<void(const std::vector<unsigned char>&)> cb);
private:
void receiveLoop();
HANDLE m_handle;
std::atomic<bool> m_running;
std::thread m_thread;
std::string m_lastError;
std::function<void(const std::vector<unsigned char>&)> m_callback;
std::mutex m_writeMutex;
};

SerialPort.cpp

#include "SerialPort.h"
#include <iostream>
#include <sstream>
#include <chrono>
#include <iomanip>
#include <mutex>
SerialPort::SerialPort()
: m_handle(INVALID_HANDLE_VALUE), m_running(false)
{
}
SerialPort::~SerialPort()
{
close();
}
static std::string GetLastErrorAsString(DWORD err)
{
if (err == 0) return std::string();
LPSTR messageBuffer = nullptr;
DWORD size = FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
nullptr, err, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), (LPSTR)&messageBuffer, 0, nullptr);
std::string message;
if (messageBuffer && size > 0) message.assign(messageBuffer, size);
if (messageBuffer) LocalFree(messageBuffer);
return message;
}
bool SerialPort::open(const std::string& portName, unsigned long baudRate)
{
if (isOpen()) return true;
std::string fullName = portName;
if (portName.rfind("\\\\.", 0) != 0) {
fullName = "\\\\.\\" + portName;
}
m_handle = CreateFileA(fullName.c_str(),
GENERIC_READ | GENERIC_WRITE,
0,
nullptr,
OPEN_EXISTING,
0,
nullptr);
if (m_handle == INVALID_HANDLE_VALUE) {
m_lastError = "CreateFile failed: " + GetLastErrorAsString(GetLastError());
return false;
}
DCB dcb;
SecureZeroMemory(&dcb, sizeof(dcb));
dcb.DCBlength = sizeof(dcb);
if (!GetCommState(m_handle, &dcb)) {
m_lastError = "GetCommState failed: " + GetLastErrorAsString(GetLastError());
CloseHandle(m_handle);
m_handle = INVALID_HANDLE_VALUE;
return false;
}
dcb.BaudRate = baudRate;
dcb.ByteSize = 8;
dcb.Parity = NOPARITY;
dcb.StopBits = ONESTOPBIT;
if (!SetCommState(m_handle, &dcb)) {
m_lastError = "SetCommState failed: " + GetLastErrorAsString(GetLastError());
CloseHandle(m_handle);
m_handle = INVALID_HANDLE_VALUE;
return false;
}
COMMTIMEOUTS timeouts;
timeouts.ReadIntervalTimeout = 50;
timeouts.ReadTotalTimeoutMultiplier = 0;
timeouts.ReadTotalTimeoutConstant = 50;
timeouts.WriteTotalTimeoutMultiplier = 0;
timeouts.WriteTotalTimeoutConstant = 50;
SetCommTimeouts(m_handle, &timeouts);
PurgeComm(m_handle, PURGE_RXCLEAR | PURGE_TXCLEAR | PURGE_RXABORT | PURGE_TXABORT);
m_running = true;
m_thread = std::thread(&SerialPort::receiveLoop, this);
return true;
}
void SerialPort::close()
{
if (!isOpen()) return;
m_running = false;
// 取消可能的阻塞 IO,尝试使 ReadFile 返回
CancelIoEx(m_handle, nullptr);
if (m_thread.joinable()) m_thread.join();
if (m_handle != INVALID_HANDLE_VALUE) {
CloseHandle(m_handle);
m_handle = INVALID_HANDLE_VALUE;
}
}
bool SerialPort::isOpen() const
{
return m_handle != INVALID_HANDLE_VALUE;
}
std::string SerialPort::getLastError() const
{
return m_lastError;
}
bool SerialPort::write(const std::vector<unsigned char>& data)
{
if (!isOpen()) {
m_lastError = "Port not open";
return false;
}
std::lock_guard<std::mutex> lock(m_writeMutex);
DWORD bytesWritten = 0;
BOOL ok = WriteFile(m_handle, data.data(), static_cast<DWORD>(data.size()), &bytesWritten, nullptr);
if (!ok) {
m_lastError = "WriteFile failed: " + GetLastErrorAsString(GetLastError());
return false;
}
return bytesWritten == data.size();
}
bool SerialPort::write(const std::string& s)
{
return write(std::vector<unsigned char>(s.begin(), s.end()));
}
void SerialPort::setReceiveCallback(std::function<void(const std::vector<unsigned char>&)> cb)
{
m_callback = std::move(cb);
}
void SerialPort::receiveLoop()
{
const DWORD bufSize = 1024;
std::vector<unsigned char> buffer(bufSize);
while (m_running && isOpen()) {
DWORD bytesRead = 0;
BOOL ok = ReadFile(m_handle, buffer.data(), bufSize, &bytesRead, nullptr);
if (!ok) {
DWORD err = GetLastError();
if (err != ERROR_IO_PENDING && err != ERROR_TIMEOUT && err != ERROR_SUCCESS) {
m_lastError = "ReadFile failed: " + GetLastErrorAsString(err);
break;
}
}
if (bytesRead > 0) {
std::vector<unsigned char> data(buffer.begin(), buffer.begin() + bytesRead);
if (m_callback) {
try {
m_callback(data);
}
catch (...) {
// 忽略回调异常
}
}
else {
std::ostringstream ossHex;
std::string printable;
for (unsigned char b : data) {
if (b >= 0x20 && b <= 0x7E) printable.push_back(static_cast<char>(b));
else printable.push_back('.');
ossHex << std::hex << std::uppercase << std::setw(2) << std::setfill('0')
<< static_cast<int>(b) << ' ';
}
// 注意:此处为线程中打印,若需线程安全或按序输出可改为其他机制
std::cout << "[串口接收] 字符: " << printable << "  HEX: " << ossHex.str() << std::endl;
}
}
std::this_thread::sleep_for(std::chrono::milliseconds(10));
}
}

使用示例main.cpp

#include <conio.h>
#include <iostream>
#include <iomanip>
#include <sstream>
#include <thread>
#include "SerialPort.h"
#include <io.h>
#include <fcntl.h>
#include <windows.h>
void recvFunc(const std::vector<unsigned char>& data)
{
std::ostringstream ossHex;
std::string printable;
for (unsigned char b : data) {
if (b >= 0x20 && b <= 0x7E) printable.push_back(static_cast<char>(b));
else printable.push_back('.');
ossHex << std::hex << std::uppercase << std::setw(2) << std::setfill('0')
<< static_cast<int>(b) << ' ';
}
// use ASCII prefix to avoid encoding issues in callback thread
std::cout << "[Receive] ASCII: " << printable << "  HEX: " << ossHex.str() << std::endl;
}
int main()
{
// 演示串口类的简单使用(需要真实串口才能收到数据)
SerialPort sp;
// 示例:打开 COM3,115200 波特(根据实际串口修改)
if (sp.open("COM3", CBR_115200)) {
std::cout << "start recv" << std::endl;
// Start the receive thread
sp.setReceiveCallback(recvFunc);
// 示例:发送字节 0x55 0xAA
{
std::vector<unsigned char> pkt = { 0x55, 0xAA };
if (sp.write(pkt)) {
std::cout << "已发送: 0x55 0xAA" << std::endl;
} else {
std::cout << "发送失败: " << sp.getLastError() << std::endl;
}
}
system("pause");
sp.close();
std::cout << "串口已关闭。\n";
}
else {
std::cout << "打开串口失败:\n";
std::cout << sp.getLastError() << "\n";
}
return 0;
}

以上就是基于C++实现轻量且线程安全的Windows串口通信封装类的详细内容,更多关于C++串口通信类的资料请关注本站其它相关文章!

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