从数据库保存和读取图片

http://www.dotnetcurry.com/ShowArticle.aspx?ID=129
看了这篇文章，解决以前做项目的一个问题。以前在从数据库读取图片的时候都是利用一个超链接，连接到另外一个页面显示图片，无法把图片直接绑定到Image控件上，而这篇文章解决了这个问题，也学习了httphandler功能。
一、保存到数据库中

protected void btnSubmit_Click(object sender, EventArgs e)

    {

        SqlConnection connection = null;

        try

        {

            FileUpload img = (FileUpload)imgUpload;

            Byte[] imgByte = null;

            if (img.HasFile && img.PostedFile != null)

            {

                //To create a PostedFile

                HttpPostedFile File = imgUpload.PostedFile;

                //Create byte Array with file len

                imgByte = new Byte[File.ContentLength];

                //force the control to load data in array

                File.InputStream.Read(imgByte, 0, File.ContentLength);

            }

            // Insert the employee name and image into db

string conn = ConfigurationManager.ConnectionStrings ["EmployeeConnString"].ConnectionString;

            connection = new SqlConnection(conn);

 

            connection.Open();

string sql = "INSERT INTO EmpDetails(empname,empimg) VALUES(@enm, @eimg) SELECT @@IDENTITY";

            SqlCommand cmd = new SqlCommand(sql, connection);

            cmd.Parameters.AddWithValue("@enm", txtEName.Text.Trim());

            cmd.Parameters.AddWithValue("@eimg", imgByte);

            int id = Convert.ToInt32(cmd.ExecuteScalar());

            lblResult.Text = String.Format("Employee ID is {0}", id);

        }

        catch

        {

            lblResult.Text = "There was an error";

        }

        finally

        {

            connection.Close();

        }

 

    }

二、从数据库中读取图片

<%@ WebHandler Language="C#" Class="ShowImage" %>

 

using System;

using System.Configuration;

using System.Web;

using System.IO;

using System.Data;

using System.Data.SqlClient;

 

public class ShowImage : IHttpHandler

{

    public void ProcessRequest(HttpContext context)

    {

       Int32 empno;

       if (context.Request.QueryString["id"] != null)

            empno = Convert.ToInt32(context.Request.QueryString["id"]);

       else

            throw new ArgumentException("No parameter specified");

 

       context.Response.ContentType = "image/jpeg";

       Stream strm = ShowEmpImage(empno);

       byte[] buffer = new byte[4096];

       int byteSeq = strm.Read(buffer, 0, 4096);

 

       while (byteSeq > 0)

       {

           context.Response.OutputStream.Write(buffer, 0, byteSeq);

           byteSeq = strm.Read(buffer, 0, 4096);

       }       

       //context.Response.BinaryWrite(buffer);

    }

 

    public Stream ShowEmpImage(int empno)

    {

 string conn = ConfigurationManager.ConnectionStrings     ["EmployeeConnString"].ConnectionString;

        SqlConnection connection = new SqlConnection(conn);

        string sql = "SELECT empimg FROM EmpDetails WHERE empid = @ID";

        SqlCommand cmd = new SqlCommand(sql,connection);

        cmd.CommandType = CommandType.Text;

        cmd.Parameters.AddWithValue("@ID", empno);

        connection.Open();

        object img = cmd.ExecuteScalar();

        try

        {

            return new MemoryStream((byte[])img);

        }

        catch

        {

            return null;

        }

        finally

        {

            connection.Close();

        }

    }

 

    public bool IsReusable

    {

        get

        {

            return false;

        }

    }

 

 

}

三、设置Image的链接
Image1.ImageUrl = "~/ShowImage.ashx?id=" + id;