[C++知识库]进程间通信（IPC）之共享内存(SharedMemory)(c++ qt c#)

1.c++进程之间

#include <stdafx.h>
#include <windows.h>
#include <iostream>

#define BUF_SIZE 4096
using namespace std;

void raedSharedMemCpp()
{
    LPVOID pBuffer;
    HANDLE hMap = OpenFileMapping(FILE_MAP_ALL_ACCESS,0,L"global_shared_memory_cpp");
    if(NULL == hMap)
    {
        DWORD err= ::GetLastError();
        cout << "打开内存失败...." << err << endl;
    }
    else
    {
        while(true)
        {
            pBuffer = MapViewOfFile(hMap, FILE_MAP_ALL_ACCESS,0,0,0);
            char buf[BUF_SIZE] = {0};
            strcpy_s(buf, (char*)pBuffer);
            cout << "读取内存：" << buf << endl;
            Sleep(100);
        }
    }
}

void writeSharedMemCpp()
{
    char buf[] = "write hello by cpp SharedMem";
    HANDLE hMap = CreateFileMapping(INVALID_HANDLE_VALUE,                     
        NULL,
        PAGE_READWRITE,
        0,
        BUF_SIZE,
        L"global_shared_memory_cpp");
    
    //获取共享内存指针
    LPVOID lpBase = MapViewOfFile(hMap, FILE_MAP_ALL_ACCESS,0,0,BUF_SIZE);
    strcpy((char*)lpBase, buf);
    Sleep(20000);

    UnmapViewOfFile(lpBase); // 解除文件映射
    CloseHandle(hMap);

    cout << "write sharedMemCpp end" << endl;

    return;
}

2.c#进程之间

#using System;
#using System.Runtime.InteropServices;
#using System.IO.MemoryMappedFiles;
#include System.Collections.Generic;
#using System.Diagnostics;

namespace ColsoleAppCsharp
{
    pulbic partial class SharedMemory
    {
        public static void WriteSharedMemCs()
        {
            int size = 1024;
            MemoryMappedFile shardMemory =                 
                 MemoryMappedFile.CreateOrOpen("global_share_memory_Cs",size);
            System.Threading.Thread.Sleep(30);
            var stream = sharedMemory.CreateViewStream(0,size);
            string value = "write by CSharp content";
            byte[] data = System.Text.Encoding.UTF8.GEtBytes(value);
            stream.Write(data, 0, data.Length);
            stream.Dispose();
        }

        public static void readSharedMemCs()
        {
            int size = 1024;
            MemoryMappedFile mmf = 
                 MemoryMappedFile.OpenExisting("global_share_memory_Cs");
            using(var mmfStream =         
                 mmf.CreateViewStream(0,size,MemoryMappedFileAccess.ReadWrite))
            {
                byte[] buffer = new byte[128];
                int nLen = 0;
                StringBuilder sb = new StringBuilder();
                do
                {
                    nLen = mmfStream.Read(buffer, 0, 128);
                    sb.AppendLine(System.Text.ASCIIEncoding.GetString(buffer));
                }while(nLen>0)
                    
                Console.WriteLine("读取内        
                     存："+sb.ToString().Replace("\0",null).TrimEnd());
            }
        }
    }
}

3.qt进程之间

#include <QSharedMemory>
#include <QDebug>
#include <QByteArray>

using namespace std;
using namespace std::chrono;

void readSharedMemQt()
{
    QSharedMemory sharedMemory;
    sharedMemory.setKey("global_share_memory_Qt");
    QString tmpStr("");
    
    while(true)
    {
        char c;
        
        // 绑定进程
        if(!sharedMemory.isAttached())
        {
            if(!sharedMemory.attach())
            {
                qDebug() << sharedMemory.errorString();
            }
            else
            {
                sharedMemory.lock();
                QByteArray arr((char*)sharedMemory.data(),sharedMemory.size());
                tmpStr = arr;
                sharedMemory.unlock();
                sharedMemory.detach();
                
                std::this_thread::sleep_for(milliseconds(30));
            }
        }
    }
}

void writeSharedMemQt()
{
    QSharedMemory sharedMemory;
    sharedMemory.setKey("global_share_memory_Qt");
    if(sharedMemory.isAttched())
    {
        qDebug() << "detach" << sharedMemory.detach();
    }

    QByteArray arr = "write by Qt shared Mem";
    int len = arr.length();
    if(!sharedMemory.create(len))
    {
        qDebug() << sharedMemory.errorString();
    }

    sharedMemory.lock();
    char* dest = reinterpret_cast<char*>(sharedMemory.data());
    for(int i = 0; i < len; i++)
    {
        dest[i] = arr[i];
    }
    sharedMemory.unlock();
}

4.c++进程与c#进程之间，读写共享内存。

参见《1.c++进程之间》和《2.c#进程之间》，一边读，另一边写就行了。

5.qt进程与c#进程之间，不行。