原文: C#從SQL server數據庫中讀取l圖片和存入圖片

本實例主要介紹如何將圖片存入數據庫。將圖片存入數據庫,首先要在數據庫中建立一張表,將存儲圖片的字段類型設為Image類型,用FileStream類、BinaryReader把圖片讀成字節的形式,賦給一個字節數組,然后用ADO.SqlCommand對象的ExecuteNonQuery()方法來把數據保存到數據庫中。主要代碼如下：

??? private void button1_Click(object sender, EventArgs e)

??????? {

????????? openFileDialog1.Filter = "*jpg|*.JPG|*.GIF|*.GIF|*.BMP|*.BMP";

??????????? if(openFileDialog1.ShowDialog()==DialogResult.OK)

??????????? {

????????????? string fullpath =openFileDialog1.FileName;//文件路徑

????????????? FileStream fs = new FileStream(fullpath, FileMode.Open);

??????????????? byte[] imagebytes =new byte[fs.Length];

??????????????? BinaryReader br = new BinaryReader(fs);

??????????????? imagebytes = br.ReadBytes(Convert.ToInt32(fs.Length));

??????????????? //打開數據庫

??????????????? SqlConnection con = new SqlConnection("server=(local);uid=sa;pwd=;database=db_05");

??????????????? con.Open();

??????????????? SqlCommand com = new SqlCommand("insert into tb_08 values(@ImageList)",con);

??????????????? com.Parameters.Add("ImageList", SqlDbType.Image);

??????????????? com.Parameters["ImageList"].Value = imagebytes;

?????????????? com.ExecuteNonQuery();

?????????????? con.Close();

???????????? }????

}

本實例主要介紹如何從數據庫中把圖片讀出來。實現本實例主要是利用SqlDataReader從數據庫中把Image字段值讀出來，賦給一個byte[]字節數組，然后使用MemoryStream類與Bitmap把圖片讀取出來。主要代碼如下：

??? private void button1_Click(object sender, EventArgs e)

??????? {

???????????????? byte[] imagebytes = null;

??????????????? //打開數據庫

??????????? SqlConnection con = new SqlConnection("server=(local);uid=sa;pwd=;database=db_05");

??????????????? con.Open();

??????????????? SqlCommand com = new SqlCommand("select top 1* from tb_09", con);

??????????????? SqlDataReader dr = com.ExecuteReader();

??????????????? while (dr.Read())

??????????????? {

??????????????????? imagebytes = (byte[])dr.GetValue(1);

??????????????? }

??????????????? dr.Close();

??????????????? com.Clone();

??????????????? con.Close();

??????????????? MemoryStream ms = new MemoryStream(imagebytes);

??????????????? Bitmap bmpt = new Bitmap(ms);

??????????????? pictureBox1.Image = bmpt;

??????? }

本實例主要介紹如何只允許輸入指定圖片格式。用OpenFileDialog控件打開圖片文件，只要將OpenFileDialog控件的Filter屬性指定為特定的圖片格式即可。例如，打開.bmp文件的圖片，主要代碼如下:

this.openFileDialog1.Filter = "bmp文件(*.bmp)|*.bmp"；

在用pictureBox控件輸入圖片時，要想統一圖片大小，只需把控件的SizeMode屬性值設為StretchImage即可，StretchImage值表示圖像的大小將調整為控件的大小。這樣，圖片的大小就統一了。

C#從SQL server數據庫中讀取l圖片和存入圖片