本文主要是介绍windows下利用文件映射实现共享内存，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
windows下利用文件映射实现共享内存的办法比较简单，下面是实现代码，细节用注释说明．调用类似linux下shm的操作．该类没有进行太多的测试，欢迎提出问题和bug～～：）
#include <windows.h>
#include <string>
#include <iostream>
#include <assert.h>
using std::string;
using std::cout;
using std::endl;
#pragma warning(disable: 4311)class shareMemory
{
private:LPWSTR shm_name_u;bool is_create_file;void * sh_base;HANDLE semaphore;HANDLE file_mapping;int addr_len;
public:/*create＿file用来说明是用磁盘文件映射还是页文件映射，如果用磁盘文件映射，共享内存不会出现存储器release后出现违规访问的问题，但是会在磁盘上建立一个文件，文件的名称由参数shm＿name给定．如果用页文件映射，则不会在磁盘上建立一个文件*/shareMemory(const string& shm_name, bool create_file=false):is_create_file(create_file){ const char * _c_shm_name = shm_name.c_str();int _size =(int)shm_name.length()+1;shm_name_u=(LPWSTR)malloc(_size*2);MultiByteToWideChar(CP_ACP,0,_c_shm_name,_size,shm_name_u,_size);semaphore = CreateSemaphore(NULL,1,1,NULL);sh_base = NULL;file_mapping = INVALID_HANDLE_VALUE;}void * shm_open(void* addr,const int length, DWORD protect){ addr_len = length; HANDLE _file_handle = INVALID_HANDLE_VALUE;if(is_create_file){_file_handle=CreateFile(shm_name_u,GENERIC_READ|GENERIC_WRITE,0,NULL,OPEN_ALWAYS,FILE_ATTRIBUTE_NORMAL,0);
#ifdef _DEBUGif(_file_handle==INVALID_HANDLE_VALUE)cout<<"can not create file! we use page file instead!";
#endif //end _DEBUG}/*打开指定名称的文件映射，如果不存在则创建一个*/file_mapping = OpenFileMapping(PAGE_READWRITE,false,shm_name_u );if(file_mapping!=NULL)goto file_mapping_exist;file_mapping = CreateFileMapping(_file_handle,NULL,PAGE_READWRITE,0,length,shm_name_u);
#ifdef _DEBUGassert(file_mapping);
#endif if(file_mapping==NULL)return NULL;
file_mapping_exist:sh_base = MapViewOfFileEx(file_mapping,protect,0,0,length,addr);CloseHandle(_file_handle);return sh_base;}/*往共享内存中写数据，返回写出数据的字节个数*/int shm_write(void *dest, void * src, int size){ if(!check_adress(dest))return -1;int _write_count = (int)sh_base+addr_len - (int)dest;if(_write_count>size)_write_count = size;
/*利用semaphore进行保护映射的区域（同一进程的不同线程调用时候才进行保护）*/WaitForSingleObject(semaphore,INFINITE);memcpy(dest,src,_write_count); ReleaseSemaphore(semaphore,1,NULL);FlushViewOfFile(sh_base,_write_count);return _write_count;}/*从共享内存中读数据，返回读出的数据字节个数＊*/
int shm_read(void* src, void * dest, int size){if(!check_adress(src))return -1;int _read_count = (int)sh_base+addr_len -(int) src;if(_read_count>size)_read_count = size;memcpy(dest,src,_read_count);return _read_count;}~shareMemory(){ UnmapViewOfFile(sh_base);free(shm_name_u);CloseHandle(semaphore);CloseHandle(file_mapping);}private :
/*进行地址检测*/bool check_adress(void* addr){if( ( (int)addr <(int)sh_base) || ((int)addr > (int)sh_base+addr_len) ){SetLastError(ERROR_ACCESS_DENIED);
#ifdef _DEBUGprintf("access denied,the destination address out of the map view!");
#endif //_DEBUGreturn false;}return true;}
};测试：
写进程的主函数：
int main()
{shareMemory sm("boost", false);void * bs = sm.shm_open(NULL,1000*4,FILE_MAP_WRITE);if(bs==NULL)return -1;int a[10];for(int i=0; i<10; ++i)a[i] = i;sm.shm_write(bs,a,10*4);Sleep(100000);
}
int main()
{shareMemory sm("boost", false);void * bs = sm.shm_open(NULL,1000,FILE_MAP_READ);if(bs==NULL){ cout<<"null";return -1;}int b[10];sm.shm_read(bs,b,10*4);for(int i=0; i<10; ++i)cout<<b[i]<<" ";
}/另一个例子//
http://blog.csdn.net/zhao_fu_lu/article/details/41730699
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