Question

我没有将图像变成二进制形式，但是现在想从数据库中获取图像数据。所以你能对此提出这样的想法吗？我已经像下面这样插入图片：

FileDialog dialog = new OpenFileDialog();
dialog.InitialDirectory = @":D\";
dialog.Filter = "(*.jpg;*.gif;*.jpeg;*.bmp)| *.jpg; *.gif; *.jpeg; *.bmp";
if (dialog.ShowDialog() == DialogResult.OK)
{
    imagename = dialog.FileName;
    pictureBox1.Image = Image.FromFile(imagename);
}
dialog = null;

然后它也存储在数据库中，但现在我必须以下一种形式检索图像我该怎么办？

Answer 1

protected void butSubmit_Click(object sender, EventArgs e)
{
SqlConnection connection = null;
try
 {
 Byte[] imgByte = null;
   if (FileUpload1.HasFile && FileUpload1.PostedFile != null)
{
 HttpPostedFile File = FileUpload1.PostedFile;
imgByte = new Byte[File.ContentLength];
 File.InputStream.Read(imgByte, 0, File.ContentLength);
 }
 connection = new SqlConnection(ConfigurationManager.ConnectionStrings         
 "ConnectionString"].ConnectionString.ToString());

 connection.Open();
string sql = "INSERT INTO Table1(title,image) VALUES(@theTitle, @theImage) SELECT     
@@IDENTITY";
 SqlCommand cmd = new SqlCommand(sql, connection);
 cmd.Parameters.AddWithValue("@theTitle", txtTitle.Text);
 cmd.Parameters.AddWithValue("@theImage", imgByte);
 int id = Convert.ToInt32(cmd.ExecuteScalar());
 lblStatus.Text = String.Format("ID is {0}", id);

 Image1.ImageUrl = "~/DisplayImg.ashx?id=" + id;
}
{
lblStatus.Text = "There was an error";
}
finally
{
 connection.Close();
}

}

Answer 2

    int O_id =Convert.ToInt32(textBox2.Text);

            SqlConnection cn = new SqlConnection(strCn);
            SqlCommand cmd = new SqlCommand("INSERT INTO BLOBTest (BLOBData, O_id) VALUES (@BLOBData,'"+O_id+"')", cn);
            String strBLOBFilePath = textBox1.Text;//Modify this path as needed.


            //Read jpg into file stream, and from there into Byte array.
            FileStream fsBLOBFile = new FileStream(strBLOBFilePath, FileMode.Open, FileAccess.Read);
            Byte[] bytBLOBData = new Byte[fsBLOBFile.Length];
            fsBLOBFile.Read(bytBLOBData, 0, bytBLOBData.Length);
            fsBLOBFile.Close();

            //Create parameter for insert command and add to SqlCommand object.
            SqlParameter prm = new SqlParameter("@BLOBData", SqlDbType.VarBinary, bytBLOBData.Length, ParameterDirection.Input, false,
                        0, 0, null, DataRowVersion.Current, bytBLOBData);
            cmd.Parameters.Add(prm);

            //Open connection, execute query, and close connection.
            cn.Open();
            cmd.ExecuteNonQuery();
            MessageBox.Show("Picture has been uploaded");
            cn.Close();

Answer 3

好的，假设您将图像存储为数据库中的BLOB字段，以下代码检索BLOB字段数据，创建内存流并从内存流中加载Bitmap：

using (SqlConnection conn = ...)
{
    conn.Open();

    using (SqlCommand cmd = new SqlCommand("SELECT Picture FROM <tableName> WHERE ...", conn)
    using (SqlDataReader reader = cmd.ExecuteReader())
    {
        if (reader.Read())
        {
            byte[] picData= reader["Picture"] as byte[] ?? null;

            if (picData!= null)
            {
                using (MemoryStream ms = new MemoryStream(picData))
                {
                    // Load the image from the memory stream. How you do it depends
                    // on whether you're using Windows Forms or WPF.
                    // For Windows Forms you could write:
                    System.Drawing.Bitmap bmp = new System.Drawing.Bitmap(ms);
                }
            }
        }
    }
}

Answer 4

using System.Data.SqlClient;


using System.Drawing;

using System.Data;

using System.IO;

using System.Drawing.Imaging;


public void Save_Image(Object sender, EventArgs e)
{

    // Create a byte[] from the input file

    int len = Upload.PostedFile.ContentLength;
    byte[] pic = new byte[len];
    Upload.PostedFile.InputStream.Read (pic, 0, len);

    // Insert the image into the database

    SqlConnection connection = new
 SqlConnection (@"server=abc\.SQLEXPRESS;database=Storage;uid=sa;pwd=sa");

    try
    {
        connection.Open ();
        SqlCommand cmd = new SqlCommand ("insert into Image " 
          + "(Picture) values (@pic)", connection);

        cmd.Parameters.Add ("@pic", pic);
        cmd.ExecuteNonQuery ();

    }
    finally 
    {
        connection.Close ();
    }
}

我们只将字节图像存储到表名中＆＃34; Image＆＃34; 它只包含一列。将字节图像存储到数据库中会占用大量数据库大小用于大型图像存储和从数据库中检索特定图像使用搜索需要更长的时间进行处理。这会导致低性能和存储问题。

如何从C＃中的数据库中获取图像？

4 个答案: