开源 C++ QT Widget 开发（十）IPC进程间通信--共享内存

mianwindow.h文件

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QSharedMemory>
#include <QTimer>

QT_BEGIN_NAMESPACE
namespace Ui {
class MainWindow;
}
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
Q_OBJECT

public:
MainWindow(QWidget *parent = nullptr);
~MainWindow();

private slots:
void on_sendButton_clicked();
void on_receiveButton_clicked();
void on_clearButton_clicked();
void checkSharedMemory();

private:
Ui::MainWindow *ui;
QSharedMemory *sharedMemory;
QTimer *checkTimer;
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```
 void setupSharedMemory();
 void updateStatus(const QString &message);
```
};
#endif // MAINWINDOW_H

mainwindow.cpp文件

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QBuffer>
#include <QDataStream>
#include <QMessageBox>
#include <QDateTime>
#include <QDebug>

MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
, ui(new Ui::MainWindow)
, sharedMemory(new QSharedMemory("MyAppSharedMemory", this))
{
ui->setupUi(this);

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 // 设置界面初始状态
 ui->statusLabel->setText("就绪");
 ui->statusLabel->setStyleSheet("QLabel { background-color: lightgray; padding: 5px; }");

 // 设置共享内存
 setupSharedMemory();

 // 创建定时器定期检查共享内存
 checkTimer = new QTimer(this);
 connect(checkTimer, &QTimer::timeout, this, &MainWindow::checkSharedMemory);
 checkTimer->start(1000); // 每秒检查一次

 // 设置初始消息
 ui->messageEdit->setText("你好，这是来自QT共享内存的消息！");

}

MainWindow::~MainWindow()
{
// 清理共享内存
if (sharedMemory->isAttached()) {
sharedMemory->detach();
}
delete ui;
}

void MainWindow::setupSharedMemory()
{
// 尝试创建或附加到共享内存
if (!sharedMemory->create(1024) && sharedMemory->error() == QSharedMemory::AlreadyExists) {
if (sharedMemory->attach()) {
updateStatus("已连接到现有共享内存");
} else {
updateStatus("无法附加到共享内存: " + sharedMemory->errorString());
}
} else if (sharedMemory->isAttached()) {
updateStatus("已创建新的共享内存");
} else {
updateStatus("无法创建共享内存: " + sharedMemory->errorString());
}
}

void MainWindow::on_sendButton_clicked()
{
if (!sharedMemory->isAttached() && !sharedMemory->attach()) {
updateStatus("无法附加到共享内存: " + sharedMemory->errorString());
return;
}

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 QString message = ui->messageEdit->text();
 if (message.isEmpty()) {
     QMessageBox::warning(this, "警告", "消息不能为空！");
     return;
 }

 // 准备数据
 QBuffer buffer;
 buffer.open(QBuffer::ReadWrite);
 QDataStream out(&buffer);

 // 写入消息和时间戳
 out << message;
 out << QDateTime::currentDateTime().toString("yyyy-MM-dd hh:mm:ss");

 // 写入共享内存
 sharedMemory->lock();
 char *to = static_cast<char*>(sharedMemory->data());
 const char *from = buffer.data().data();
 memcpy(to, from, qMin(sharedMemory->size(), static_cast<int>(buffer.size())));
 sharedMemory->unlock();

 updateStatus("消息已发送到共享内存: " + message);
 ui->messageEdit->clear();

}

void MainWindow::on_receiveButton_clicked()
{
if (!sharedMemory->isAttached() && !sharedMemory->attach()) {
updateStatus("无法附加到共享内存: " + sharedMemory->errorString());
return;
}

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 // 从共享内存读取数据
 sharedMemory->lock();
 QByteArray byteArray(static_cast<const char*>(sharedMemory->constData()), sharedMemory->size());
 sharedMemory->unlock();

 QBuffer buffer(&byteArray);
 buffer.open(QBuffer::ReadOnly);
 QDataStream in(&buffer);

 QString message;
 QString timestamp;
 in >> message >> timestamp;

 if (message.isEmpty()) {
     ui->receivedTextEdit->append("没有可用的消息");
 } else {
     QString displayText = QString("[%1] %2").arg(timestamp, message);
     ui->receivedTextEdit->append(displayText);
     updateStatus("收到新消息: " + message);
 }

}

void MainWindow::on_clearButton_clicked()
{
ui->receivedTextEdit->clear();
updateStatus("已清除接收的消息");
}

void MainWindow::checkSharedMemory()
{
// 定期检查共享内存中是否有新数据
if (!sharedMemory->isAttached() && !sharedMemory->attach()) {
return;
}

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 sharedMemory->lock();
 QByteArray byteArray(static_cast<const char*>(sharedMemory->constData()), sharedMemory->size());
 sharedMemory->unlock();

 QBuffer buffer(&byteArray);
 buffer.open(QBuffer::ReadOnly);
 QDataStream in(&buffer);

 QString message;
 QString timestamp;
 in >> message >> timestamp;

 if (!message.isEmpty()) {
     // 更新状态提示有新消息
     ui->statusLabel->setText("有新消息可用!");
     ui->statusLabel->setStyleSheet("QLabel { background-color: lightgreen; padding: 5px; }");
 }

}

void MainWindow::updateStatus(const QString &message)
{
ui->statusLabel->setText(message);
ui->statusLabel->setStyleSheet("QLabel { background-color: lightblue; padding: 5px; }");

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 // 3秒后恢复普通状态
 QTimer::singleShot(3000, this, [this]() {
     ui->statusLabel->setText("就绪");
     ui->statusLabel->setStyleSheet("QLabel { background-color: lightgray; padding: 5px; }");
 });

}

mainwindow.ui文件

在工程文件夹下用记事本打开

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<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MainWindow</class>
 <widget class="QMainWindow" name="MainWindow">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>600</width>
    <height>400</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>QT共享内存IPC示例</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <layout class="QVBoxLayout" name="verticalLayout">
    <item>
     <widget class="QLabel" name="label">
      <property name="text">
       <string>发送消息:</string>
      </property>
     </widget>
    </item>
    <item>
     <layout class="QHBoxLayout" name="horizontalLayout">
      <item>
       <widget class="QLineEdit" name="messageEdit"/>
      </item>
      <item>
       <widget class="QPushButton" name="sendButton">
        <property name="text">
         <string>发送</string>
        </property>
       </widget>
      </item>
     </layout>
    </item>
    <item>
     <widget class="QLabel" name="label_2">
      <property name="text">
       <string>接收的消息:</string>
      </property>
     </widget>
    </item>
    <item>
     <widget class="QTextEdit" name="receivedTextEdit"/>
    </item>
    <item>
     <layout class="QHBoxLayout" name="horizontalLayout_2">
      <item>
       <widget class="QPushButton" name="receiveButton">
        <property name="text">
         <string>接收消息</string>
        </property>
       </widget>
      </item>
      <item>
       <widget class="QPushButton" name="clearButton">
        <property name="text">
         <string>清除</string>
        </property>
       </widget>
      </item>
      <item>
       <spacer name="horizontalSpacer">
        <property name="orientation">
         <enum>Qt::Horizontal</enum>
        </property>
        <property name="sizeHint" stdset="0">
         <size>
          <width>40</width>
          <height>20</height>
         </size>
        </property>
       </spacer>
      </item>
     </layout>
    </item>
    <item>
     <widget class="QLabel" name="statusLabel"/>
    </item>
   </layout>
  </widget>
 </widget>
 <resources/>
 <connections/>
</ui>

四、效果演示

输入消息

发送消息

接收消息