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如何通过ADO.NET读取数据库中的图片？

admin2019-03-29  92
问题 如何通过ADO.NET读取数据库中的图片？
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答案// Assumes that connection is a valid SqlConnection object. SqlCommand command = new SqlCommand("SELECT pub_id, logo FROM pub_info", connection); // Writes the BLOB to a file (*.bmp). FileStream stream; // Streams the BLOB to the FileStream object. BinaryWriter writer; // Size of the BLOB buffer. int bufferSize = 100; // The BLOB byte[] buffer to be filled by GetBytes. byte[] outByte = new byte[bufferSize]; // The bytes returned from GetBytes. long retval; // The starting position in the BLOB output. long startIndex = 0; // The publisher id to use in the file name. string pubID = ""; // Open the connection and read data into the DataReader. connection.Open(); SqlDataReader reader = command.ExecuteReader(CommandBehavior.SequentialAccess); while (reader.Read()){ // Get the publisher id, which must occur before getting the logo. pubID = reader.GetString(0); // Create a file to hold the output. stream = new FileStream("logo" + pubID + ".bmp", FileMode.OpenOrCreate, FileAccess.Write); writer = new BinaryWriter(stream); // Reset the starting byte for the new BLOB. startIndex = 0; // Read bytes into outByte[] and retain the number of bytes returned. retval = reader.GetBytes(1, startIndex, outByte, 0, bufferSize); // Continue while there are bytes beyond the size of the buffer. while (retval == bufferSize) { writer.Write(outByte); writer.Flush(); // Reposition start index to end of last buffer and fill buffer. startIndex += bufferSize; retval = reader.GetBytes(1, startIndex, outByte, 0, bufferSize); } // Write the remaining buffer. writer.Write(outByte, 0, (int)retval - 1); writer.Flush(); // Close the output file. writer.Close(); stream.Close(); }// Close the reader and the connection. reader.Close(); connection.Close();
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