Question

我正在为我的项目使用Windows Form和MySQL。因为我想保存图像并检索它。

我已经创建了一个名为'image'的表，

CREATE TABLE `image` (
    `id` INT(15) NOT NULL AUTO_INCREMENT,
    `extension` VARCHAR(50) NOT NULL,
    `image` LONGBLOB NOT NULL,
    PRIMARY KEY (`id`)
)
ENGINE=MyISAM
ROW_FORMAT=DEFAULT
AUTO_INCREMENT=2

并且

OpenFileDialog open = new OpenFileDialog();
            // image filters
            open.Filter = "Image Files(*.jpg; *.jpeg; *.gif; *.bmp; *.png)|*.jpg; *.jpeg; *.gif; *.bmp; *.png";
            if (open.ShowDialog() == DialogResult.OK)
            {                
                txt_imagePath.Text = open.FileName;
            }

            hp.getConnStr();
            try
            {
                MySqlConnection connection = new MySqlConnection(hp.myConnStr);
                MySqlCommand command = connection.CreateCommand();                
                command.CommandText = "insert into image (image) values ('"+txt_imagePath.Text +"')";
                command.Connection.Open();
                command.ExecuteNonQuery();
                command.Connection.Close();
            }

在“浏览”按钮单击事件中，..

文件已成功保存。现在我想检索那张图片并在图片框中显示。所以我试试这个波纹管代码，..

 MySqlConnection connection = new MySqlConnection(hp.myConnStr);
                MySqlCommand command = connection.CreateCommand();
                MySqlDataReader Reader;
                command.CommandText = "select image from image";
                connection.Open();
                Reader = command.ExecuteReader();
                while (Reader.Read())
                {
                   pictureBox1.Image = new Bitmap(Reader[0].ToString()); 
                }
                connection.Close();

但没用。

请帮帮我。

Answer 1

我希望这样的事情会有所帮助：

public Bitmap loadImage(int imgID)
        {

            MySqlDataReader myData;
            MySqlCommand cmd = new MySqlCommand();

            string SQL;
            byte[] rawData;
            MemoryStream ms;
            UInt32 FileSize;
            Bitmap outImage;

            SQL = "SELECT ImageName, ImageSize, Image FROM Images WHERE ImageID =";
            SQL += imgID.ToString();

            try
            {
                cmd.Connection = connection;
                cmd.CommandText = SQL;

                myData = cmd.ExecuteReader();

                if (!myData.HasRows)
                    throw new Exception("There are no blobs to save");

                myData.Read();

                FileSize = myData.GetUInt32(myData.GetOrdinal("ImageSize"));
                rawData = new byte[FileSize];

                myData.GetBytes(myData.GetOrdinal("Image"), 0, rawData, 0, (Int32)FileSize);


                ms = new MemoryStream(rawData);
                outImage = new Bitmap(ms);
                ms.Close();
                ms.Dispose();

                myData.Close();
                myData.Dispose();

                cmd.Dispose();

                return outImage;


            }
            catch (MySqlException ex)
            {
                MessageBox.Show(ex.Message);
                return null;
            }

        }

Answer 2

您应该将blob字段读为MemoryStream并使用Image设置为控件的Image.FromStream()属性。

Answer 3

while (Reader.Read()) 
{ 
  pictureBox1.Image = new Bitmap(new MemoryStream((byte[])Reader.GetValue(0)));
}

这应该这样做。 reader.GetValue（）返回MySQL blob上的字节数组，这就是诀窍。

如何在MySQL数据库中检索图像longblob？

3 个答案: