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Oracle® Objects for OLE C++ Class Library Developer's Guide 10g Release 2 (10.2) Part Number B14308-01 |
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# Example: Writing a Blob

Note: For more information about sample code, see Sample Code and Applications.

#include <oracl.h>

#include <iostream.h>

#include <fstream.h>

// Example for OBlob::Write

int main()

{

//Initialize oo4o, connect, execute sql

OStartup();

ODatabase odb("ExampleDB", "scott", "tiger");

ODynaset odyn(odb, "SELECT * FROM PART");

if (!odyn.IsOpen())

{

cout <<"Connect Error: "<<odb.GetErrorText()<<endl;

cout <<"SQL Error: "<<odyn.GetErrorText()<<endl;

return 1;

}

//prior to modifying a LOB for the first time,

//we must first insert an Empty LOB and then commit

OValue val;

val.SetEmpty();

odyn.AddNewRecord();

oresult ores = odyn.SetFieldValue((const char *)"PART_IMAGE", val);

ores = odyn.Update();

OBlob oblob;

odyn.StartEdit();

odyn.GetFieldValue("PART_IMAGE", &oblob);

unsigned char *buffer = 0;

try

{

// calculate an optimum buffersize of approximately 32k bytes

unsigned long optchunk = oblob.GetOptimumChunkSize();

unsigned int bufsize = ((int)(32768/optchunk)) *optchunk;

buffer = (unsigned char *)malloc(bufsize);

//open file and get file size

fstream fs;

fs.open("C:\\Oracle\\Ora81\\Oo4o\\Cpp\\Workbook\\Lob\\partimage.dat", ios::in);

fs.setmode(filebuf::binary);

fs.seekg(0, ios::end);

unsigned long filesize = fs.tellg();

fs.seekg(0, ios::beg);

unsigned long totalwritten = 0;

unsigned long amtread = 0;

int piecetype = OLOB_FIRST_PIECE;

//By taking advantage of streaming we get the best performance

//and we don't need to allocate a huge buffer.

if (filesize <= bufsize)

piecetype = OLOB_ONE_PIECE;

else

oblob.EnableStreaming(filesize);

while(totalwritten != filesize)

{

fs.read(buffer, bufsize);

amtread = fs.gcount();

oblob.Write(buffer, amtread, piecetype);

totalwritten = totalwritten + amtread;

if ((filesize - totalwritten)<=bufsize)

piecetype = OLOB_LAST_PIECE;

else

piecetype = OLOB_NEXT_PIECE;

}

oblob.DisableStreaming();

ores = odyn.Update();

fs.close();

}

catch(OException E)

{

cout<<E.GetFailedMethodName()<< " Error: "<<E.GetErrorText()<<endl;

}

if (buffer)

free(buffer);

OShutdown();

return 0;

}