把图片转换成二进制--把二进制转换成图片

 private void button1_Click(object sender, EventArgs e)

        {

            string path = this.textBox1.Text;

            byte[] imgBytesIn = SaveImage(path);

            ShowImgByByte(imgBytesIn);

            //Parameters.Add("@Photo", SqlDbType.Binary).Value = imgBytesIn;

           

        }

        //将图片以二进制流

        public byte[] SaveImage(String path)

        {            

            FileStream fs = new FileStream(path, FileMode.Open, FileAccess.Read); //将图片以文件流的形式进行保存

            BinaryReader br = new BinaryReader(fs);

            byte[] imgBytesIn = br.ReadBytes((int)fs.Length);  //将流读入到字节数组中

            return imgBytesIn;

        }

        //现实二进制流代表的图片

        public void ShowImgByByte(byte[] imgBytesIn)

        {

            MemoryStream ms = new MemoryStream(imgBytesIn);

            pictureBox1.Image = Image.FromStream(ms);

        }

二、将图片保存到数据库中，并从数据库中读取：

#region 将图片从数据库中读取

        /// <summary>

        /// 将图片从数据库中读取

        /// </summary>

        /// <param name="xs_ID">要读取图片的学号</param>

        /// <param name="ph">pictureBox1控件名</param>

        public void get_photo(string xs_ID, PictureBox ph)//将图片从数据库中读取

        {

            byte[] imagebytes = null;

            getcon();

            SqlCommand con = new SqlCommand("select * from S_jiben where S_num='" + xs_ID + "'", link);

            SqlDataReader dr = con.ExecuteReader();

            while (dr.Read())

            {

                imagebytes =(byte[])dr.GetValue(18);

            }

            dr.Close();

            con_close();

            MemoryStream ms = new MemoryStream(imagebytes);

            Bitmap bmpt = new Bitmap(ms);

            ph.Image = bmpt; 

        }

        #endregion

        #region

        public void SaveImage(string MID, OpenFileDialog openF)//将图片以二进制存入数据库中

        {

            string strimg = openF.FileName.ToString();  //记录图片的所在路径

            FileStream fs = new FileStream(strimg, FileMode.Open, FileAccess.Read); //将图片以文件流的形式进行保存

            BinaryReader br = new BinaryReader(fs);

            byte[] imgBytesIn = br.ReadBytes((int)fs.Length);  //将流读入到字节数组中

            getcon();

            StringBuilder strSql = new StringBuilder();

            strSql.Append("update S_jiben Set xs_photo=@Photo where S_num=" + MID);

            SqlCommand cmd = new SqlCommand(strSql.ToString(), link);

            cmd.Parameters.Add("@Photo", SqlDbType.Binary).Value = imgBytesIn;

            cmd.ExecuteNonQuery();

            con_close();

        }

        #endregion