which database are you using ?Access.I have met same problem as you before. I suggest these codes above are right.The real problem are hided in the code that you read from Database with.Please check those codes carefully.
SqlConnection pubsConn = new SqlConnection("Data Source=localhost;Integrated Security=SSPI;Initial Catalog=pubs;"); SqlCommand logoCMD = new SqlCommand("SELECT pub_id, logo FROM pub_info", pubsConn); FileStream fs; // Writes the BLOB to a file (*.bmp). BinaryWriter bw; // Streams the BLOB to the FileStream object. int bufferSize = 100; // Size of the BLOB buffer. byte[] outbyte = new byte[bufferSize]; // The BLOB byte[] buffer to be filled by GetBytes. long retval; // The bytes returned from GetBytes. long startIndex = 0; // The starting position in the BLOB output. string pub_id = ""; // The publisher id to use in the file name. // Open the connection and read data into the DataReader. pubsConn.Open(); SqlDataReader myReader = logoCMD.ExecuteReader(CommandBehavior.SequentialAccess); while (myReader.Read()) { // Get the publisher id, which must occur before getting the logo. pub_id = myReader.GetString(0); // Create a file to hold the output. fs = new FileStream("logo" + pub_id + ".bmp", FileMode.OpenOrCreate, FileAccess.Write); bw = new BinaryWriter(fs); // Reset the starting byte for the new BLOB. startIndex = 0; // Read the bytes into outbyte[] and retain the number of bytes returned. retval = myReader.GetBytes(1, startIndex, outbyte, 0, bufferSize); // Continue reading and writing while there are bytes beyond the size of the buffer. while (retval == bufferSize) { bw.Write(outbyte); bw.Flush(); // Reposition the start index to the end of the last buffer and fill the buffer. startIndex+= bufferSize; retval = myReader.GetBytes(1, startIndex, outbyte, 0, bufferSize); } // Write the remaining buffer. bw.Write(outbyte); bw.Flush(); // Close the output file. bw.Close(); fs.Close(); } // Close the reader and the connection. myReader.Close(); pubsConn.Close();
byte[] b=(byte[])dr["ImageField"]
MemoryStream ms=new MemoryStream(b);
Image img=Image.FromStream(ms); ****
PictureBox1.Image=img;
可是在****语句处包错：使用了无效参数。
错在哪。
I suggest these codes above are right.The real problem are hided in the code that you read from Database with.Please check those codes carefully.
SqlCommand logoCMD = new SqlCommand("SELECT pub_id, logo FROM pub_info", pubsConn);
FileStream fs; // Writes the BLOB to a file (*.bmp).
BinaryWriter bw; // Streams the BLOB to the FileStream object.
int bufferSize = 100; // Size of the BLOB buffer.
byte[] outbyte = new byte[bufferSize]; // The BLOB byte[] buffer to be filled by GetBytes.
long retval; // The bytes returned from GetBytes.
long startIndex = 0; // The starting position in the BLOB output.
string pub_id = ""; // The publisher id to use in the file name.
// Open the connection and read data into the DataReader.
pubsConn.Open();
SqlDataReader myReader = logoCMD.ExecuteReader(CommandBehavior.SequentialAccess);
while (myReader.Read())
{
// Get the publisher id, which must occur before getting the logo.
pub_id = myReader.GetString(0);
// Create a file to hold the output.
fs = new FileStream("logo" + pub_id + ".bmp", FileMode.OpenOrCreate, FileAccess.Write);
bw = new BinaryWriter(fs);
// Reset the starting byte for the new BLOB.
startIndex = 0;
// Read the bytes into outbyte[] and retain the number of bytes returned.
retval = myReader.GetBytes(1, startIndex, outbyte, 0, bufferSize);
// Continue reading and writing while there are bytes beyond the size of the buffer.
while (retval == bufferSize)
{
bw.Write(outbyte);
bw.Flush();
// Reposition the start index to the end of the last buffer and fill the buffer.
startIndex+= bufferSize;
retval = myReader.GetBytes(1, startIndex, outbyte, 0, bufferSize);
}
// Write the remaining buffer.
bw.Write(outbyte);
bw.Flush();
// Close the output file.
bw.Close();
fs.Close();
}
// Close the reader and the connection.
myReader.Close();
pubsConn.Close();
C#读取的方法,楼上的朋友已经解决