Qt-共享内存QSharedMemory

 

相关资料：

https://blog.csdn.net/qq_33266987/article/details/60872001   QString 和 char* 之间的转换（以及QByteArray）

https://www.cnblogs.com/ybqjymy/p/12557703.html      Qt QString转char[]数组

https://liang.blog.csdn.net/article/details/108894720    Qt 读写共享内存

https://blog.csdn.net/gdutlyp/article/details/50468677   Qt学习—qt共享内存的使用

https://download.csdn.net/download/zhujianqiangqq/19125137    代码包下载

 

代码实例：

.pro

 1 QT       += core gui
 2 
 3 greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
 4 
 5 CONFIG += c++11
 6 
 7 # The following define makes your compiler emit warnings if you use
 8 # any Qt feature that has been marked deprecated (the exact warnings
 9 # depend on your compiler). Please consult the documentation of the
10 # deprecated API in order to know how to port your code away from it.
11 DEFINES += QT_DEPRECATED_WARNINGS
12 
13 # You can also make your code fail to compile if it uses deprecated APIs.
14 # In order to do so, uncomment the following line.
15 # You can also select to disable deprecated APIs only up to a certain version of Qt.
16 #DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0
17 
18 SOURCES += \
19     main.cpp \
20     mainwindow.cpp
21 
22 HEADERS += \
23     mainwindow.h
24 
25 FORMS += \
26     mainwindow.ui
27 
28 # Default rules for deployment.
29 qnx: target.path = /tmp/$${TARGET}/bin
30 else: unix:!android: target.path = /opt/$${TARGET}/bin
31 !isEmpty(target.path): INSTALLS += target
View Code

main.cpp

 1 #include "mainwindow.h"
 2 
 3 #include <QApplication>
 4 
 5 int main(int argc, char *argv[])
 6 {
 7     QApplication a(argc, argv);
 8     MainWindow w;
 9     w.show();
10     return a.exec();
11 }
View Code

mainwindow.h

 1 #ifndef MAINWINDOW_H
 2 #define MAINWINDOW_H
 3 
 4 #include <QMainWindow>
 5 
 6 #include <QSharedMemory>
 7 
 8 
 9 //测试使用的数据结构
10 typedef struct{
11     int age;
12     char name[12];
13 }DataInfo;//注意考虑内存对齐，尽量凑为8的倍数，不够的添加保留位
14 
15 
16 QT_BEGIN_NAMESPACE
17 namespace Ui { class MainWindow; }
18 QT_END_NAMESPACE
19 
20 class MainWindow : public QMainWindow
21 {
22     Q_OBJECT
23 
24 public:
25     MainWindow(QWidget *parent = nullptr);
26     ~MainWindow();
27 
28 private slots:
29     void on_pushButton_clicked();
30 
31     void on_pushButton_2_clicked();
32 
33     void on_pushButton_3_clicked();
34 
35     void on_pushButton_4_clicked();
36 
37     void on_pushButton_5_clicked();
38 
39     void on_pushButton_11_clicked();
40 
41     void on_pushButton_6_clicked();
42 
43     void on_pushButton_7_clicked();
44 
45     void on_pushButton_8_clicked();
46 
47     void on_pushButton_9_clicked();
48 
49     void on_pushButton_10_clicked();
50 
51     void on_pushButton_12_clicked();
52 
53     void on_pushButton_13_clicked();
54 
55     void on_pushButton_14_clicked();
56 
57 private:
58     Ui::MainWindow *ui;
59 
60     QSharedMemory *m_pShareMemory; //定义共享内存实例指针
61     int m_nIndex = 0;
62 };
63 #endif // MAINWINDOW_H
View Code

mainwindow.cpp

  1 #include "mainwindow.h"
  2 #include "ui_mainwindow.h"
  3 
  4 MainWindow::MainWindow(QWidget *parent)
  5     : QMainWindow(parent)
  6     , ui(new Ui::MainWindow)
  7 {
  8     ui->setupUi(this);
  9 }
 10 
 11 MainWindow::~MainWindow()
 12 {
 13     delete ui;
 14 }
 15 
 16 //利用QSharedMemory类创建实例对象时，必须为该共享内存指定关键字(即为该共享内存起一个名字)。
 17 //只有当共享内存被设置了关键字之后，才可以执行创建create)、关联attach()等操作。为共享内存指定关键字有
 18 void MainWindow::on_pushButton_clicked()
 19 {
 20     m_pShareMemory = new QSharedMemory("QSharedMemoryExample", this); //构造实例对象
 21     // m_pShareMemory->setKey("QSharedMemoryExample");// 也可以生成对象后给名称，咱们在这里不使用这个
 22 }
 23 
 24 // 为QSharedMemory类实例对象创建一个空间大小为size的共享内存，该内存空间默认的访问方式为可读可写。
 25 // 共享内存创建成功返回true，否则返回false。QSharedMemory类定义一个枚举类变量AccessMode，
 26 // 指定了两种共享内存的访问方式：
 27 // QSharedMemory::ReadOnly   只读方式访问共享内存
 28 // QSharedMemory::ReadWrite  读写方式访问共享内存
 29 void MainWindow::on_pushButton_12_clicked()
 30 {
 31     m_pShareMemory->create(512, QSharedMemory::ReadWrite);
 32 }
 33 
 34 //将以关键字key命名的共享内存和当前程序进行关联，共享内存默认的访问方式为可读写。如果程序和共享内存关联成功，
 35 //返回true，否则返回false。
 36 void MainWindow::on_pushButton_2_clicked()
 37 {
 38     m_pShareMemory->attach();
 39 }
 40 
 41 //解除共享内存和程序的关联，即调用该函数后，程序不可以再访问共享内存。如果该共享内存被多个程序实例所关联，
 42 //当最后一个程序实例和共享内存解除关联后，该共享内存将由操作系统自动释放掉。分离操作成功，
 43 //返回true。如果返回false，通常意味着该共享内存和程序分离失败，或者其他程序当前正在访问该共享内存，分离操作执行失败。
 44 void MainWindow::on_pushButton_3_clicked()
 45 {
 46     m_pShareMemory->detach();
 47 }
 48 
 49 //该函数用来判断程序(调用该函数的程序)是否和共享内存进行关联，是返回true，否返回false。
 50 void MainWindow::on_pushButton_4_clicked()
 51 {
 52     ui->textEdit->append(QString::number(m_pShareMemory->isAttached()));
 53 }
 54 
 55 //Qt应用程序通过关键字来辨识共享内存。key ()函数用来获取共享内存的关键字，如果没有指定实例对象的关键字，
 56 //或者共享内存的关键字是由nativeKey ()函数指定的话，则返回空。
 57 void MainWindow::on_pushButton_5_clicked()
 58 {
 59     ui->textEdit->append(m_pShareMemory->key());
 60 }
 61 
 62 //setKey  () 函数用来为共享内存段设定关键字 ( 为共享内存命名 ) ，
 63 //如果参数 key 的值和构造函数或者之前指定的关键字相同的话，则该函数将不做任何操作，直接返回。
 64 void MainWindow::on_pushButton_11_clicked()
 65 {
 66     m_pShareMemory->setKey(ui->lineEdit_2->text());
 67 }
 68 
 69 void MainWindow::on_pushButton_6_clicked()
 70 {
 71     m_pShareMemory->lock();
 72 }
 73 
 74 void MainWindow::on_pushButton_7_clicked()
 75 {
 76     m_pShareMemory->unlock();
 77 }
 78 
 79 void MainWindow::on_pushButton_8_clicked()
 80 {
 81     //当共享内存出错时，调用该函数显示相应的错误代码。
 82     //m_pShareMemory->error();
 83     //当共享内存出错时，调用该函数，以文本形式显示错误原因。
 84     ui->textEdit->append(m_pShareMemory->errorString());
 85 }
 86 
 87 //程序关联共享内存的前提下，调用该函数返回共享内存中数据的起始地址。如果没有关联共享内存，则返回0
 88 void MainWindow::on_pushButton_9_clicked()
 89 {
 90     std::stringstream ss1;
 91     ss1 << m_pShareMemory->data();
 92     std::string name = ss1.str();
 93     ui->textEdit->append(QString::fromStdString(name));
 94 }
 95 
 96 //调用该函数将返回程序所关联的共享内存的大小(字节)。如果没有关联的共享内存，则返回0
 97 void MainWindow::on_pushButton_10_clicked()
 98 {
 99     ui->textEdit->append(QString::number(m_pShareMemory->size()));
100 }
101 
102 
103 void MainWindow::on_pushButton_13_clicked()
104 {
105     DataInfo oInfo;// = {71, "zhangsan"};
106     m_nIndex = m_nIndex + 1;
107     oInfo.age = m_nIndex;
108     //
109     char*  ch;
110     QByteArray ba = ui->lineEdit->text().toLatin1();
111     ch = ba.data();
112     //
113     memcpy(oInfo.name, ch, 12);
114     m_pShareMemory->lock();        //锁定共享内存
115     m_pShareMemory->lock();//上锁
116     char *shm_addr = (char *)m_pShareMemory->data();//获取共享内存映射首地址
117     memcpy(shm_addr, &oInfo, sizeof(oInfo));//写入数据, 这里注意写入的数据长度不能超过共享内存的大小
118     m_pShareMemory->unlock();//解锁
119 }
120 
121 void MainWindow::on_pushButton_14_clicked()
122 {
123     DataInfo oInfo = {0, ""};
124     m_pShareMemory->lock();//加锁
125     memcpy(&oInfo, m_pShareMemory->constData(), sizeof(oInfo));
126     m_pShareMemory->unlock();//解锁
127     QString sInfo = "age %1 name %2";
128     sInfo = sInfo.arg(oInfo.age).arg(oInfo.name);
129     ui->lineEdit->setText(sInfo);
130 }
View Code

mainwindow.ui

  1 <?xml version="1.0" encoding="UTF-8"?>
  2 <ui version="4.0">
  3  <class>MainWindow</class>
  4  <widget class="QMainWindow" name="MainWindow">
  5   <property name="geometry">
  6    <rect>
  7     <x>0</x>
  8     <y>0</y>
  9     <width>747</width>
 10     <height>444</height>
 11    </rect>
 12   </property>
 13   <property name="windowTitle">
 14    <string>MainWindow</string>
 15   </property>
 16   <widget class="QWidget" name="centralwidget">
 17    <widget class="QPushButton" name="pushButton">
 18     <property name="geometry">
 19      <rect>
 20       <x>550</x>
 21       <y>10</y>
 22       <width>75</width>
 23       <height>23</height>
 24      </rect>
 25     </property>
 26     <property name="text">
 27      <string>创建内存对象</string>
 28     </property>
 29    </widget>
 30    <widget class="QPushButton" name="pushButton_2">
 31     <property name="geometry">
 32      <rect>
 33       <x>550</x>
 34       <y>70</y>
 35       <width>75</width>
 36       <height>23</height>
 37      </rect>
 38     </property>
 39     <property name="text">
 40      <string>联接内存</string>
 41     </property>
 42    </widget>
 43    <widget class="QPushButton" name="pushButton_3">
 44     <property name="geometry">
 45      <rect>
 46       <x>550</x>
 47       <y>100</y>
 48       <width>75</width>
 49       <height>23</height>
 50      </rect>
 51     </property>
 52     <property name="text">
 53      <string>分离内存</string>
 54     </property>
 55    </widget>
 56    <widget class="QPushButton" name="pushButton_4">
 57     <property name="geometry">
 58      <rect>
 59       <x>484</x>
 60       <y>140</y>
 61       <width>141</width>
 62       <height>23</height>
 63      </rect>
 64     </property>
 65     <property name="text">
 66      <string>判断共享内存的关联状态</string>
 67     </property>
 68    </widget>
 69    <widget class="QPushButton" name="pushButton_5">
 70     <property name="geometry">
 71      <rect>
 72       <x>464</x>
 73       <y>170</y>
 74       <width>161</width>
 75       <height>23</height>
 76      </rect>
 77     </property>
 78     <property name="text">
 79      <string>获取共享内存的关键字</string>
 80     </property>
 81    </widget>
 82    <widget class="QPushButton" name="pushButton_6">
 83     <property name="geometry">
 84      <rect>
 85       <x>450</x>
 86       <y>220</y>
 87       <width>91</width>
 88       <height>23</height>
 89      </rect>
 90     </property>
 91     <property name="text">
 92      <string>锁定共享内存</string>
 93     </property>
 94    </widget>
 95    <widget class="QPushButton" name="pushButton_7">
 96     <property name="geometry">
 97      <rect>
 98       <x>544</x>
 99       <y>220</y>
100       <width>91</width>
101       <height>23</height>
102      </rect>
103     </property>
104     <property name="text">
105      <string>解锁共享内存</string>
106     </property>
107    </widget>
108    <widget class="QPushButton" name="pushButton_8">
109     <property name="geometry">
110      <rect>
111       <x>450</x>
112       <y>250</y>
113       <width>181</width>
114       <height>23</height>
115      </rect>
116     </property>
117     <property name="text">
118      <string>错误原因</string>
119     </property>
120    </widget>
121    <widget class="QPushButton" name="pushButton_9">
122     <property name="geometry">
123      <rect>
124       <x>450</x>
125       <y>280</y>
126       <width>181</width>
127       <height>23</height>
128      </rect>
129     </property>
130     <property name="text">
131      <string>获取共享内存的地址</string>
132     </property>
133    </widget>
134    <widget class="QPushButton" name="pushButton_10">
135     <property name="geometry">
136      <rect>
137       <x>450</x>
138       <y>310</y>
139       <width>181</width>
140       <height>23</height>
141      </rect>
142     </property>
143     <property name="text">
144      <string>获取共享内存的大小</string>
145     </property>
146    </widget>
147    <widget class="QTextEdit" name="textEdit">
148     <property name="geometry">
149      <rect>
150       <x>10</x>
151       <y>10</y>
152       <width>411</width>
153       <height>291</height>
154      </rect>
155     </property>
156    </widget>
157    <widget class="QLineEdit" name="lineEdit">
158     <property name="geometry">
159      <rect>
160       <x>10</x>
161       <y>350</y>
162       <width>411</width>
163       <height>20</height>
164      </rect>
165     </property>
166    </widget>
167    <widget class="QLineEdit" name="lineEdit_2">
168     <property name="geometry">
169      <rect>
170       <x>430</x>
171       <y>200</y>
172       <width>113</width>
173       <height>20</height>
174      </rect>
175     </property>
176    </widget>
177    <widget class="QPushButton" name="pushButton_11">
178     <property name="geometry">
179      <rect>
180       <x>560</x>
181       <y>200</y>
182       <width>131</width>
183       <height>23</height>
184      </rect>
185     </property>
186     <property name="text">
187      <string>设置共享内存的关键字</string>
188     </property>
189    </widget>
190    <widget class="QPushButton" name="pushButton_12">
191     <property name="geometry">
192      <rect>
193       <x>550</x>
194       <y>40</y>
195       <width>75</width>
196       <height>23</height>
197      </rect>
198     </property>
199     <property name="text">
200      <string>分配内存</string>
201     </property>
202    </widget>
203    <widget class="QPushButton" name="pushButton_13">
204     <property name="geometry">
205      <rect>
206       <x>450</x>
207       <y>350</y>
208       <width>75</width>
209       <height>23</height>
210      </rect>
211     </property>
212     <property name="text">
213      <string>写</string>
214     </property>
215    </widget>
216    <widget class="QPushButton" name="pushButton_14">
217     <property name="geometry">
218      <rect>
219       <x>560</x>
220       <y>350</y>
221       <width>75</width>
222       <height>23</height>
223      </rect>
224     </property>
225     <property name="text">
226      <string>读</string>
227     </property>
228    </widget>
229   </widget>
230   <widget class="QMenuBar" name="menubar">
231    <property name="geometry">
232     <rect>
233      <x>0</x>
234      <y>0</y>
235      <width>747</width>
236      <height>23</height>
237     </rect>
238    </property>
239   </widget>
240   <widget class="QStatusBar" name="statusbar"/>
241  </widget>
242  <resources/>
243  <connections/>
244 </ui>
View Code

 

posted on 2021-05-27 14:16  疯狂delphi  阅读(226)  评论(0)  编辑  收藏  举报

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