如何创建内存映射文件，并对其进行写入与读取数据

本文介绍如何使用CreateFileMapping，MapViewOfFile创建内存映射文件，向内存映射文件中写入数据，读取数据。

#include <iostream>#include <assert.h>#include <Windows.h>#define BAD_POS 0xFFFFFFFF // returned by SetFilePointer and GetFileSize#define SUCCESS 0using namespace std;typedef DWORD mmf_share_mode;typedef DWORD mmf_access_mode;typedef DWORD mmf_flags;int main(){cout << "create memorymapfile..." << endl;const char* shared_name = "share_memory_file_test";const char* file_name = "d:\\testMmf.mmf";const DWORD mmf_size = 512*1024;//存取模式mmf_access_mode access_mode = (GENERIC_READ|GENERIC_WRITE);//共享模式mmf_share_mode share_mode = FILE_SHARE_READ | FILE_SHARE_WRITE;//文件属性mmf_flags flags = FILE_FLAG_SEQUENTIAL_SCAN;//|FILE_FLAG_WRITE_THROUGH|FILE_FLAG_NO_BUFFERING;//创建文件HANDLE mmHandle = CreateFile(file_name,access_mode, share_mode, NULL, OPEN_ALWAYS,flags,NULL);DWORD error_code;if (mmHandle == INVALID_HANDLE_VALUE){error_code = GetLastError();cout << "创建mmf失败:" << error_code << endl;}else{DWORD high_size;DWORD file_size = GetFileSize(mmHandle, &high_size);if (file_size == BAD_POS && (error_code = GetLastError()) != SUCCESS) {CloseHandle(mmHandle);cout << "error：" << error_code << endl;}cout << "create mmf sucessfully" << endl;//assert(file_size == 0);DWORD size_high = 0;//创建文件映射，如果要创建内存页面文件的映射，第一个参数设置为INVALID_HANDLE_VALUEHANDLE mmfm = CreateFileMapping(mmHandle,NULL,PAGE_READWRITE,size_high, mmf_size, shared_name);error_code = GetLastError();if(SUCCESS != error_code){cout << "createFileMapping error" << error_code << endl;}else{if(mmfm == NULL){if(mmHandle != INVALID_HANDLE_VALUE){CloseHandle(mmHandle);}}else{//char write_chars[] = "hello chars";//size_t position = 0;//DWORD written = 0;//const size_t write_chars_size = sizeof(write_chars);//WriteFile(mmHandle,write_chars,write_chars_size,&written,NULL);size_t view_size = 1024*256;DWORD view_access = FILE_MAP_ALL_ACCESS;//获得映射视图char* mmfm_base_address = (char*)MapViewOfFile(mmfm,view_access,0,0,view_size);if(mmfm_base_address == NULL){error_code = GetLastError();if(error_code != SUCCESS){cout << "error code " << error_code << endl;}}else{char write_chars[] = "this is test by kandy!";const size_t write_chars_size = sizeof(write_chars);//向内存映射视图中写数据CopyMemory((PVOID)mmfm_base_address, write_chars, write_chars_size);//memcpy(mmfm_base_address,write_chars,write_chars_size);size_t position = 0;char read_chars[write_chars_size];//读数据memcpy(read_chars,mmfm_base_address,write_chars_size);cout << "read chars : " << read_chars << endl;//卸载映射UnmapViewOfFile(mmfm_base_address);//关闭内存映射文件CloseHandle(mmfm);//关闭文件CloseHandle(mmHandle);}}}}system("pause");exit(0);return EXIT_SUCCESS;}