开源 C++ QT Widget 开发（十三）IPC通讯--本地套接字 (Local Socket)

   文章的目的为了记录使用C++ 进行QT Widget 开发学习的经历。临时学习，完成app的开发。开发流程和要点有些记忆模糊，赶紧记录，防止忘记。
 
相关链接：

开源 C++ QT Widget 开发（一）工程文件结构-CSDN博客

开源 C++ QT Widget 开发（二）基本控件应用-CSDN博客

开源 C++ QT Widget 开发（三）图表--波形显示器-CSDN博客

开源 C++ QT Widget 开发（四）文件--二进制文件查看编辑-CSDN博客

 开源 C++ QT Widget 开发（五）通讯--串口调试-CSDN博客

开源 C++ QT Widget 开发（六）通讯--TCP调试-CSDN博客

开源 C++ QT Widget 开发（七）线程--多线程及通讯-CSDN博客

开源 C++ QT Widget 开发（八）网络--Http文件下载-CSDN博客

开源 C++ QT Widget 开发（九）图表--仪表盘-CSDN博客

开源 C++ QT Widget 开发（十）IPC进程间通信--共享内存-CSDN博客

开源 C++ QT Widget 开发（十一）进程间通信--Windows 窗口通信-CSDN博客

开源 C++ QT Widget 开发（十二）图表--环境监测表盘-CSDN博客

推荐链接：

开源 java android app 开发（一）开发环境的搭建-CSDN博客

开源 java android app 开发（二）工程文件结构-CSDN博客

开源 java android app 开发（三）GUI界面布局和常用组件-CSDN博客

开源 java android app 开发（四）GUI界面重要组件-CSDN博客

开源 java android app 开发（五）文件和数据库存储-CSDN博客

开源 java android app 开发（六）多媒体使用-CSDN博客

开源 java android app 开发（七）通讯之Tcp和Http-CSDN博客

开源 java android app 开发（八）通讯之Mqtt和Ble-CSDN博客

开源 java android app 开发（九）后台之线程和服务-CSDN博客

开源 java android app 开发（十）广播机制-CSDN博客

开源 java android app 开发（十一）调试、发布-CSDN博客

开源 java android app 开发（十二）封库.aar-CSDN博客

推荐链接：

开源C# .net mvc 开发（一）WEB搭建_c#部署web程序-CSDN博客

开源 C# .net mvc 开发（二）网站快速搭建_c#网站开发-CSDN博客

开源 C# .net mvc 开发（三）WEB内外网访问(VS发布、IIS配置网站、花生壳外网穿刺访问)_c# mvc 域名下不可訪問內網,內網下可以訪問域名-CSDN博客

开源 C# .net mvc 开发（四）工程结构、页面提交以及显示_c#工程结构-CSDN博客

开源 C# .net mvc 开发（五）常用代码快速开发_c# mvc开发-CSDN博客

内容：Qt 有名管道 IPC 通信代码，本地套接字 (Local Socket)。这是在同一台机器上进行进程间通信的最常用、最推荐的方式之一。它基于 Windows 的命名管道和 Unix 的本地域套接字，提供了类似于网络 TCP 的流式通信接口。

目录：

1.功能介绍

2.核心代码分析

3.所有源码

4.显示效果

一、功能介绍

工作原理：一个服务器进程 (QLocalServer) 监听一个唯一的服务器名（如 "MyAwesomeServer"）。客户端进程 (QLocalSocket) 通过该服务器名连接到服务器。之后，双方就可以像操作网络套接字一样进行读写。

适用场景：需要可靠、双向、基于流的通信。例如，一个主程序与它的插件进程、守护进程或辅助工具进行通信。

二、核心代码分析

1) 服务器端代码分析
1. 服务器启动机制

removeServer() 是必须的，避免"地址已在使用"错误

服务器名称 "MyLocalServer" 是通信的唯一标识

支持启动/停止切换功能

void MainWindow::on_startServer_clicked()
{
    // 清理旧实例 - 防止资源泄漏
    QLocalServer::removeServer(serverName); // 关键：清理可能存在的旧服务器
    
    if (server->listen(serverName)) { // 监听指定名称的服务器
        // 成功监听
    }
}

2. 连接管理机制

单客户端设计：每次只保持一个连接，新连接会替换旧连接

信号槽机制实现异步事件处理

自动内存管理：使用 deleteLater() 安全释放资源

void MainWindow::on_newConnection()
{
    clientConnection = server->nextPendingConnection(); // 获取新连接
    connect(clientConnection, &QLocalSocket::readyRead, this, &MainWindow::on_readyRead);
    connect(clientConnection, &QLocalSocket::disconnected, this, &MainWindow::on_disconnected);
}

3. 数据通信机制

使用 readAll() 而非 readLine()，更稳定但需要自定义协议

UTF-8 编码确保跨平台兼容性

简单的字符串协议，

void MainWindow::on_readyRead()
{
    QByteArray data = clientConnection->readAll(); // 读取所有可用数据
    QString message = QString::fromUtf8(data).trimmed();
}

正确的资源释放顺序，避免内存泄漏

MainWindow::~MainWindow()
{
    if (server) {
        server->close();    // 先关闭
        delete server;      // 再删除
    }
    // 类似的客户端连接清理
}

2) 客户端代码分析
架构设计

class QLocalSocket; // 前向声明

QLocalSocket *socket; // 客户端套接字对象

核心机制分析
1. 连接管理机制
 

void MainWindow::on_connectButton_clicked()
{
    if (!socket) {
        socket = new QLocalSocket(this); // 父对象管理生命周期
        // 连接所有信号槽
    }
    socket->connectToServer(serverName); // 异步连接
}

技术要点：

连接/断开切换功能

异步连接操作，不阻塞UI线程

父对象管理内存，自动释放

2. 错误处理机制

// 兼容旧版本的错误处理
connect(socket, SIGNAL(error(QLocalSocket::LocalSocketError)), 
        this, SLOT(on_errorOccurred(QLocalSocket::LocalSocketError)));

void MainWindow::on_errorOccurred(QLocalSocket::LocalSocketError socketError)
{
    Q_UNUSED(socketError); // 不使用错误代码，直接获取错误字符串
    ui->textBrowser->append("Error: " + socket->errorString());
}

使用传统 SIGNAL/SLOT 语法确保版本兼容性

errorString() 提供人类可读的错误信息

Q_UNUSED 避免编译器警告

3. 状态管理
 

void MainWindow::on_connected()
{
    ui->connectButton->setText("Disconnect"); // UI状态更新
}

void MainWindow::on_disconnected()
{
    ui->connectButton->setText("Connect"); // UI状态恢复
}

3. 通信协议分析
当前实现

// 发送端
QByteArray data = message.toUtf8(); // 简单字符串编码
socket->write(data);

// 接收端  
QByteArray data = socket->readAll(); // 读取所有数据
QString message = QString::fromUtf8(data).trimmed();

三、所有源码

服务器和客户端.pro文件都需要添加

QT += core gui network

1.  服务器端

mianwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QLocalServer>
#include <QLocalSocket>

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_startServer_clicked();
    void on_sendMessage_clicked();
    void on_newConnection();
    void on_readyRead();
    void on_disconnected();

private:
    Ui::MainWindow *ui;
    QLocalServer *server;
    QLocalSocket *clientConnection;
};
#endif // MAINWINDOW_H

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QMessageBox>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
    , server(nullptr)
    , clientConnection(nullptr)
{
    ui->setupUi(this);
    setWindowTitle("Server - Named Pipe Example");
}

MainWindow::~MainWindow()
{
    if (server) {
        server->close();
        delete server;
    }
    if (clientConnection) {
        clientConnection->close();
        delete clientConnection;
    }
    delete ui;
}

void MainWindow::on_startServer_clicked()
{
    if (server) {
        server->close();
        delete server;
        server = nullptr;
    }

    server = new QLocalServer(this);
    connect(server, &QLocalServer::newConnection, this, &MainWindow::on_newConnection);

    QString serverName = "MyLocalServer";
    if (server->listen(serverName)) {
        ui->textBrowser->append("Server started successfully!");
        ui->textBrowser->append("Listening on: " + serverName);
        ui->startServer->setText("Stop Server");
    } else {
        ui->textBrowser->append("Failed to start server: " + server->errorString());
        delete server;
        server = nullptr;
    }
}

void MainWindow::on_newConnection()
{
    if (clientConnection) {
        clientConnection->close();
        delete clientConnection;
    }

    clientConnection = server->nextPendingConnection();
    connect(clientConnection, &QLocalSocket::readyRead, this, &MainWindow::on_readyRead);
    connect(clientConnection, &QLocalSocket::disconnected, this, &MainWindow::on_disconnected);

    ui->textBrowser->append("New client connected!");
}

void MainWindow::on_readyRead()
{
    if (clientConnection && clientConnection->canReadLine()) {
        QByteArray data = clientConnection->readLine();
        QString message = QString::fromUtf8(data).trimmed();
        ui->textBrowser->append("Received: " + message);
    }
}

void MainWindow::on_disconnected()
{
    ui->textBrowser->append("Client disconnected");
    if (clientConnection) {
        clientConnection->deleteLater();
        clientConnection = nullptr;
    }
}

void MainWindow::on_sendMessage_clicked()
{
    if (!clientConnection || clientConnection->state() != QLocalSocket::ConnectedState) {
        QMessageBox::warning(this, "Warning", "No client connected!");
        return;
    }

    QString message = ui->lineEdit->text();
    if (message.isEmpty()) {
        return;
    }

    QByteArray data = (message + "\n").toUtf8();
    clientConnection->write(data);
    clientConnection->flush();

    ui->textBrowser->append("Sent: " + message);
    ui->lineEdit->clear();
}

ui_mainwindow.h

/********************************************************************************
** Form generated from reading UI file 'mainwindow.ui'
**
** Created by: Qt User Interface Compiler version 5.14.2
**
** WARNING! All changes made in this file will be lost when recompiling UI file!
********************************************************************************/

#ifndef UI_MAINWINDOW_H
#define UI_MAINWINDOW_H

#include <QtCore/QVariant>
#include <QtWidgets/QApplication>
#include <QtWidgets/QHBoxLayout>
#include <QtWidgets/QLineEdit>
#include <QtWidgets/QMainWindow>
#include <QtWidgets/QMenuBar>
#include <QtWidgets/QPushButton>
#include <QtWidgets/QStatusBar>
#include <QtWidgets/QTextEdit>
#include <QtWidgets/QVBoxLayout>
#include <QtWidgets/QWidget>

QT_BEGIN_NAMESPACE

class Ui_MainWindow
{
public:
    QWidget *centralwidget;
    QWidget *verticalLayoutWidget;
    QVBoxLayout *verticalLayout;
    QTextEdit *textBrowser;
    QLineEdit *lineEdit;
    QPushButton *sendMessage;
    QPushButton *startServer;
    QHBoxLayout *horizontalLayout;
    QMenuBar *menubar;
    QStatusBar *statusbar;

    void setupUi(QMainWindow *MainWindow)
    {
        if (MainWindow->objectName().isEmpty())
            MainWindow->setObjectName(QString::fromUtf8("MainWindow"));
        MainWindow->resize(753, 365);
        centralwidget = new QWidget(MainWindow);
        centralwidget->setObjectName(QString::fromUtf8("centralwidget"));
        verticalLayoutWidget = new QWidget(centralwidget);
        verticalLayoutWidget->setObjectName(QString::fromUtf8("verticalLayoutWidget"));
        verticalLayoutWidget->setGeometry(QRect(10, 1, 741, 301));
        verticalLayout = new QVBoxLayout(verticalLayoutWidget);
        verticalLayout->setObjectName(QString::fromUtf8("verticalLayout"));
        verticalLayout->setContentsMargins(0, 0, 0, 0);
        textBrowser = new QTextEdit(verticalLayoutWidget);
        textBrowser->setObjectName(QString::fromUtf8("textBrowser"));

        verticalLayout->addWidget(textBrowser);

        lineEdit = new QLineEdit(verticalLayoutWidget);
        lineEdit->setObjectName(QString::fromUtf8("lineEdit"));

        verticalLayout->addWidget(lineEdit);

        sendMessage = new QPushButton(verticalLayoutWidget);
        sendMessage->setObjectName(QString::fromUtf8("sendMessage"));

        verticalLayout->addWidget(sendMessage);

        startServer = new QPushButton(verticalLayoutWidget);
        startServer->setObjectName(QString::fromUtf8("startServer"));

        verticalLayout->addWidget(startServer);

        horizontalLayout = new QHBoxLayout();
        horizontalLayout->setObjectName(QString::fromUtf8("horizontalLayout"));

        verticalLayout->addLayout(horizontalLayout);

        MainWindow->setCentralWidget(centralwidget);
        menubar = new QMenuBar(MainWindow);
        menubar->setObjectName(QString::fromUtf8("menubar"));
        menubar->setGeometry(QRect(0, 0, 753, 26));
        MainWindow->setMenuBar(menubar);
        statusbar = new QStatusBar(MainWindow);
        statusbar->setObjectName(QString::fromUtf8("statusbar"));
        MainWindow->setStatusBar(statusbar);

        retranslateUi(MainWindow);

        QMetaObject::connectSlotsByName(MainWindow);
    } // setupUi

    void retranslateUi(QMainWindow *MainWindow)
    {
        MainWindow->setWindowTitle(QCoreApplication::translate("MainWindow", "MainWindow", nullptr));
        sendMessage->setText(QCoreApplication::translate("MainWindow", "\345\217\221\351\200\201\346\266\210\346\201\257", nullptr));
        startServer->setText(QCoreApplication::translate("MainWindow", "\345\220\257\345\212\250\346\234\215\345\212\241\345\231\250", nullptr));
    } // retranslateUi

};

namespace Ui {
    class MainWindow: public Ui_MainWindow {};
} // namespace Ui

QT_END_NAMESPACE

#endif // UI_MAINWINDOW_H

2.  客户端代码

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QLocalSocket>

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_connectButton_clicked();
    void on_sendButton_clicked();
    void on_connected();
    void on_readyRead();
    void on_disconnected();
    void on_errorOccurred(QLocalSocket::LocalSocketError socketError); // 修改参数

private:
    Ui::MainWindow *ui;
    QLocalSocket *socket;
};
#endif // MAINWINDOW_H

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QMessageBox>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
    , socket(nullptr)
{
    ui->setupUi(this);
    setWindowTitle("Client - Named Pipe Example");
}

MainWindow::~MainWindow()
{
    if (socket) {
        socket->close();
        delete socket;
    }
    delete ui;
}

void MainWindow::on_connectButton_clicked()
{
    if (socket && socket->state() == QLocalSocket::ConnectedState) {
        socket->disconnectFromServer();
        return;
    }

    if (!socket) {
        socket = new QLocalSocket(this);
        connect(socket, &QLocalSocket::connected, this, &MainWindow::on_connected);
        connect(socket, &QLocalSocket::readyRead, this, &MainWindow::on_readyRead);
        connect(socket, &QLocalSocket::disconnected, this, &MainWindow::on_disconnected);
        // 兼容旧版本 Qt 的错误处理方式
               #if QT_VERSION >= QT_VERSION_CHECK(5, 15, 0)
                   connect(socket, &QLocalSocket::errorOccurred, this, &MainWindow::on_errorOccurred);
               #else
                   connect(socket, QOverload<QLocalSocket::LocalSocketError>::of(&QLocalSocket::error),
                           this, &MainWindow::on_errorOccurred);
               #endif
    }

    QString serverName = "MyLocalServer";
    socket->connectToServer(serverName);

    ui->textBrowser->append("Connecting to server...");
}

void MainWindow::on_connected()
{
    ui->textBrowser->append("Connected to server successfully!");
    ui->connectButton->setText("Disconnect");
}

void MainWindow::on_readyRead()
{
    if (socket && socket->canReadLine()) {
        QByteArray data = socket->readLine();
        QString message = QString::fromUtf8(data).trimmed();
        ui->textBrowser->append("Received: " + message);
    }
}

void MainWindow::on_disconnected()
{
    ui->textBrowser->append("Disconnected from server");
    ui->connectButton->setText("Connect");
}

void MainWindow::on_errorOccurred(QLocalSocket::LocalSocketError socketError)
{
    Q_UNUSED(socketError);
    ui->textBrowser->append("Error: " + socket->errorString());
}

void MainWindow::on_sendButton_clicked()
{
    if (!socket || socket->state() != QLocalSocket::ConnectedState) {
        QMessageBox::warning(this, "Warning", "Not connected to server!");
        return;
    }

    QString message = ui->lineEdit->text();
    if (message.isEmpty()) {
        return;
    }

    QByteArray data = (message + "\n").toUtf8();
    socket->write(data);
    socket->flush();

    ui->textBrowser->append("Sent: " + message);
    ui->lineEdit->clear();
}

ui_mianwindow.h

/********************************************************************************
** Form generated from reading UI file 'mainwindow.ui'
**
** Created by: Qt User Interface Compiler version 5.14.2
**
** WARNING! All changes made in this file will be lost when recompiling UI file!
********************************************************************************/

#ifndef UI_MAINWINDOW_H
#define UI_MAINWINDOW_H

#include <QtCore/QVariant>
#include <QtWidgets/QApplication>
#include <QtWidgets/QLineEdit>
#include <QtWidgets/QMainWindow>
#include <QtWidgets/QMenuBar>
#include <QtWidgets/QPushButton>
#include <QtWidgets/QStatusBar>
#include <QtWidgets/QTextBrowser>
#include <QtWidgets/QVBoxLayout>
#include <QtWidgets/QWidget>

QT_BEGIN_NAMESPACE

class Ui_MainWindow
{
public:
    QWidget *centralwidget;
    QWidget *verticalLayoutWidget;
    QVBoxLayout *verticalLayout;
    QTextBrowser *textBrowser;
    QLineEdit *lineEdit;
    QPushButton *sendButton;
    QPushButton *connectButton;
    QMenuBar *menubar;
    QStatusBar *statusbar;

    void setupUi(QMainWindow *MainWindow)
    {
        if (MainWindow->objectName().isEmpty())
            MainWindow->setObjectName(QString::fromUtf8("MainWindow"));
        MainWindow->resize(581, 401);
        centralwidget = new QWidget(MainWindow);
        centralwidget->setObjectName(QString::fromUtf8("centralwidget"));
        verticalLayoutWidget = new QWidget(centralwidget);
        verticalLayoutWidget->setObjectName(QString::fromUtf8("verticalLayoutWidget"));
        verticalLayoutWidget->setGeometry(QRect(10, 10, 561, 321));
        verticalLayout = new QVBoxLayout(verticalLayoutWidget);
        verticalLayout->setObjectName(QString::fromUtf8("verticalLayout"));
        verticalLayout->setContentsMargins(0, 0, 0, 0);
        textBrowser = new QTextBrowser(verticalLayoutWidget);
        textBrowser->setObjectName(QString::fromUtf8("textBrowser"));

        verticalLayout->addWidget(textBrowser);

        lineEdit = new QLineEdit(verticalLayoutWidget);
        lineEdit->setObjectName(QString::fromUtf8("lineEdit"));

        verticalLayout->addWidget(lineEdit);

        sendButton = new QPushButton(verticalLayoutWidget);
        sendButton->setObjectName(QString::fromUtf8("sendButton"));

        verticalLayout->addWidget(sendButton);

        connectButton = new QPushButton(verticalLayoutWidget);
        connectButton->setObjectName(QString::fromUtf8("connectButton"));

        verticalLayout->addWidget(connectButton);

        MainWindow->setCentralWidget(centralwidget);
        menubar = new QMenuBar(MainWindow);
        menubar->setObjectName(QString::fromUtf8("menubar"));
        menubar->setGeometry(QRect(0, 0, 581, 26));
        MainWindow->setMenuBar(menubar);
        statusbar = new QStatusBar(MainWindow);
        statusbar->setObjectName(QString::fromUtf8("statusbar"));
        MainWindow->setStatusBar(statusbar);

        retranslateUi(MainWindow);

        QMetaObject::connectSlotsByName(MainWindow);
    } // setupUi

    void retranslateUi(QMainWindow *MainWindow)
    {
        MainWindow->setWindowTitle(QCoreApplication::translate("MainWindow", "MainWindow", nullptr));
        sendButton->setText(QCoreApplication::translate("MainWindow", "\345\217\221\351\200\201\346\266\210\346\201\257", nullptr));
        connectButton->setText(QCoreApplication::translate("MainWindow", "\350\277\236\346\216\245", nullptr));
    } // retranslateUi

};

namespace Ui {
    class MainWindow: public Ui_MainWindow {};
} // namespace Ui

QT_END_NAMESPACE

#endif // UI_MAINWINDOW_H

四、显示效果