如何从下面的代码中获取BLOB数据? [英] How to get the BLOB data from the below code?

问题描述

我刚刚使用lpBits存储二进制数据.但是在数据库中，我只能看到24bytes.如何转换找到图像的二进制数据.要将其存储在数据库中.

I have just used lpBits to store the binary data. But in database i see only 24bytes. How to convert the find the binary data of the image. To store it in the database.

HDC hScrDC = ::GetDC(NULL);
	HDC hMemDC = NULL;
 
	BYTE *lpBitmapBits = NULL; 
 
	int nWidth = GetSystemMetrics(SM_CXSCREEN);
	int nHeight = GetSystemMetrics(SM_CYSCREEN); 
 
	hMemDC = ::CreateCompatibleDC(hScrDC); 
 
	BITMAPINFO bi; 
	ZeroMemory(&bi, sizeof(BITMAPINFO));
	bi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
	bi.bmiHeader.biWidth = nWidth;
	bi.bmiHeader.biHeight = nHeight;
	bi.bmiHeader.biPlanes = 1;
	bi.bmiHeader.biBitCount = 24;
 
	HBITMAP bitmap = ::CreateDIBSection(hMemDC, &bi, DIB_RGB_COLORS, (LPVOID*)&lpBitmapBits, NULL, 0);
	HGDIOBJ oldbmp = ::SelectObject(hMemDC, bitmap); 
 
	::BitBlt(hMemDC, 0, 0, nWidth, nHeight, hScrDC, 0, 0, SRCCOPY);
 
	BITMAPFILEHEADER bh;
	ZeroMemory(&bh, sizeof(BITMAPFILEHEADER));
	bh.bfType = 0x4d42; //bitmap 
	bh.bfOffBits = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);
	bh.bfSize = bh.bfOffBits + ((nWidth*nHeight)*3);

         lpBits = (LPBYTE) GlobalAlloc(GMEM_FIXED, bi.bmiHeader.biSizeImage);	
 
	CFile file;	
	char buffer[1000];
	DWORD threadId;
  int value = 10;
  //hThread = CreateThread( NULL, 0, runThread, &value, 0, &threadId);
	for(int c=0;c<10;c++)
	{
		 sprintf_s(buffer,"D:\image%u.jpg",c);
		 CString sName(buffer);  
         LPCTSTR lpszName = sName;  
		if(file.Open(lpszName, CFile::modeCreate | CFile::modeWrite))
		{ 
			file.Write(&bh, sizeof(BITMAPFILEHEADER));
			file.Write(&(bi.bmiHeader), sizeof(BITMAPINFOHEADER));
			file.Write(lpBitmapBits, 3 * nWidth * nHeight);
			file.Close();
			Sleep(10000);
		}
		
	}
	::SelectObject(hMemDC, oldbmp);
	::DeleteObject(bitmap);
	::DeleteObject(hMemDC);
	::ReleaseDC(NULL, hScrDC);

推荐答案

您的问题是什么?
字符串D:\image%u.jpg应该为D:\\image%u.jpg

What''s your question?
The string D:\image%u.jpg should be D:\\image%u.jpg

首先，位图(BMP)格式不会自动转换为jpeg(JPG).
BLOB 代表 B inary L arge OB ject，用于将二进制数据存储到数据库中.这可以是一切.因此，您可以将整个位图存储在数据库中.
您应该在数据库中打开到BLOB的流，然后将其写入文件中.
问候.

For the first: bitmap (BMP) format is not automatically converted to jpeg (JPG).
BLOB stands for Binary Large OBject, and is used to store binary data into a database. This can be everything. So you can store the whole bitmap in a database.
You should open a stream to your BLOB in database and write to it like into a file.
Regards.

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