Qt工作笔记-进程间的通信(通过QSharedMemory)
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Qt工作笔记-进程间的通信(通过QSharedMemory)
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程序運行截圖如下:
分享端分享圖片:
接受端接受圖片:
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分享端的邏輯:
1.創建一個QSharedMemory,并設置一個key值;
2.查看這個內存是不是被使用,如果被使用就斷開;
3.調用create進行創建;
4.使用memcpy把要寫入的數據放入QSharedMemory中(內部一般會使用互斥鎖技術,鎖住資源)
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讀取端邏輯:
1.創建一個QSharedMemory,把key值設置為分享端相同的key值;
2.使用attach連接上這個QSharedMemory;
3.以讀取字節的方式讀取QSharedMemory中的數據(內部一般會使用互斥鎖技術,鎖住資源);
4.使用detach端口對這個QSharedMemory的連接。
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源碼如下:
接收端:
widget.h
#ifndef WIDGET_H #define WIDGET_H#include <QWidget>class QSharedMemory;namespace Ui { class Widget; }class Widget : public QWidget {Q_OBJECTpublic:explicit Widget(QWidget *parent = 0);~Widget();public slots:void btnClicked();private:Ui::Widget *ui;QSharedMemory *m_sharedMemory; };#endif // WIDGET_Hmain.cpp
#include "widget.h" #include <QApplication>int main(int argc, char *argv[]) {QApplication a(argc, argv);Widget w;w.show();return a.exec(); }widget.cpp
#include "widget.h" #include "ui_widget.h"#include <QDebug> #include <QBuffer> #include <QDataStream> #include <QImage> #include <QPixmap> #include <QSharedMemory>Widget::Widget(QWidget *parent) :QWidget(parent),ui(new Ui::Widget) {ui->setupUi(this);connect(ui->pushButton,SIGNAL(clicked(bool)),this,SLOT(btnClicked()));m_sharedMemory=new QSharedMemory("169254"); }Widget::~Widget() {delete ui; }void Widget::btnClicked(){if(!m_sharedMemory->attach()){qDebug()<<"SharedMemory attach failed!";return;}QBuffer buffer;QDataStream in(&buffer);QImage image;m_sharedMemory->lock();buffer.setData((char *)m_sharedMemory->constData(),m_sharedMemory->size());buffer.open(QBuffer::ReadOnly);in>>image;m_sharedMemory->unlock();m_sharedMemory->detach();ui->label->setPixmap(QPixmap::fromImage(image));}?
分析端:
widget.h
#ifndef WIDGET_H #define WIDGET_H#include <QWidget>class QSharedMemory;namespace Ui { class Widget; }class Widget : public QWidget {Q_OBJECTpublic:explicit Widget(QWidget *parent = 0);~Widget();public slots:void btnClicked();private:Ui::Widget *ui;QSharedMemory *m_sharedMemory; };#endif // WIDGET_Hmain.cpp
#include "widget.h" #include <QApplication>int main(int argc, char *argv[]) {QApplication a(argc, argv);Widget w;w.show();return a.exec(); }widget.cpp
#include "widget.h" #include "ui_widget.h"#include <QBuffer> #include <QFileDialog> #include <QDataStream> #include <QSharedMemory> #include <QDebug> #include <QPixmap> #include <QImage>Widget::Widget(QWidget *parent) :QWidget(parent),ui(new Ui::Widget) {ui->setupUi(this);connect(ui->pushButton,SIGNAL(clicked(bool)),this,SLOT(btnClicked()));m_sharedMemory=new QSharedMemory("169254"); }Widget::~Widget() {delete ui; }void Widget::btnClicked() {if(m_sharedMemory->isAttached()){if(!m_sharedMemory->detach()){qDebug()<<"sharedMemory detach falied!";return;}}QString fileName=QFileDialog::getOpenFileName(this,"","","Images(*.*)");QImage image(fileName);ui->label->setPixmap(QPixmap::fromImage(image).scaled(128,128));QBuffer buffer;buffer.open(QBuffer::ReadWrite);QDataStream out(&buffer);out<<image;if(!m_sharedMemory->create(buffer.size())){qDebug()<<m_sharedMemory->errorString()<<" created failed!";return;}m_sharedMemory->lock();char *to=(char*)m_sharedMemory->data();const char *from=buffer.data().data();memcpy(to,from,qMin(m_sharedMemory->size(),(int)buffer.size()));m_sharedMemory->unlock(); }?
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