图片上传并保存到数据库以及显示图片

此处是用保存图片相对路径的方法，上传图片。

1. 首先创建数据库表：

create table images
(
image_ID int primary key identity,
image_Wpath varchar(50)not null
)
--image_Wpath用来保存图片的相对路径

2. 页面：

    Add a new folder named images, it will be used in the following steps.

   上传图片：一个UploadFile控件，id=“inputFile”，一个 Button控件，id="btnUpload". lblMessage显示提示信息。

   显示图片：txtImageID 用来输入想要现实的图片ID，lblPath显示所选图片的绝对路径。btnShow按钮

   效果图如下所示。

 

3. 后台代码（1）图片上传： 

 protected void btnUpload_Click(object sender, EventArgs e)
        {

            string fileName = inputFile.FileName;//get the file name
            string type = fileName.Substring(name.LastIndexOf(".") + 1); //get the file type

            //string fileExt= System.IO.Path.GetExtension(inputFile.FileName); //获取文件后缀名 也可以

            //if（type == ".jpg" || type == ".gif" || type == ".bmp" || type == ".png")

            string ipath = Server.MapPath("images") + "\\" + fileName; //获取文件路径 
            string wpath = "images\\" + fileName; //设置文件保存相对路径  (我们存放图片的文件夹名)
            if (type == "jpg" || type == "gif" || type == "bmp" || type == "png")
            {
                inputFile.SaveAs(ipath);
                int j = InsertToImages(wpath); //自定义方法，保存图片至数据库

                if (j > 0)
                {
                    lblMessage.Text = "Saved!";
                }

                else

                {

                      lblMessage.Text = "Failed to save!";

                }
            }

           else

           {

                  lblMessage.Text = "The file format is not correct, please change another one!";

           }

        }

         /// <summary>
        /// save the image in db table
        /// </summary>
        /// <param name="wpath">wpath</param>
        /// <returns>int i</returns>
        private int InsertToImages(string wpath)
        {
            SqlConnection conn = new SqlConnection(@"Data Source=stkwx028\sqlexpress;Initial Catalog=BBS;Integrated Security=True");
            SqlCommand cmd = new SqlCommand();
            cmd.Connection = conn;
            cmd.CommandText = @"INSERT INTO images(image_Wpath)
                                            VALUES(@wpath)";
            cmd.Parameters.AddWithValue("@wpath", wpath);
            conn.Open();
            int i = cmd.ExecuteNonQuery();
            conn.Close();
            return i;
        }

后台代码（2）显示图片：
       protected void btnShow_Click(object sender, EventArgs e)
        {
            int imageid = Convert.ToInt32(txtPathID.Text);
            string wpath = GetWpathByID(imageid);
            Image1.ImageUrl = wpath;
            lblPath.Text = wpath;
        }
        /// <summary>
        /// Get Wpath by imageID
        /// </summary>
        /// <param name="imageID">imageID</param>
        /// <returns>string wpath</returns>
        private string GetWpathByID(int imageID)
        {
            SqlConnection conn = new SqlConnection(@"Data Source=stkwx028\sqlexpress;Initial Catalog=BBS;Integrated Security=True");
            string wpath = "";
            SqlCommand cmd = new SqlCommand();
            cmd.Connection = conn;
            cmd.CommandText = @"SELECT * FROM images
                                               WHERE image_ID=@image_ID";
            cmd.Parameters.AddWithValue("@image_ID", imageID);
            conn.Open();
            SqlDataReader sdr = cmd.ExecuteReader();
            while (sdr.Read())
            {
                wpath=sdr["image_Wpath"].ToString();
            }
            conn.Close();
            return wpath;
        }