将图片插入数据库并使用asp.net读取出来的正确方法
A、将图片输入到数据库中，以下是一个将图片输入到数据库的代码片断：（完整的DEMO程序见附录一）
FileStream fs=File.OpenRead(filePath.Text);
byte[] content=new byte[fs.Length];
fs.Read(content, 0,content.Length);
fs.Close();
SqlConnection conn=new SqlConnection("Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=DatabaseImage;Data Source=(local)");
conn.Open();
SqlCommand comm=conn.CreateCommand();
comm.CommandText="insert into Images(Image, contentType) values(@image, @contentType)";
comm.CommandType=CommandType.Text;
comm.Parameters.Add("@image", SqlDbType.Image).Value=content;
comm.Parameters.Add("@contentType", SqlDbType.NVarChar).Value=
GetContentType(new FileInfo(filePath.Text).Extension.Remove(0,1));
if(comm.ExecuteNonQuery()==1)
{
MessageBox.Show("Successfully insert image into database!");
}
else
{
MessageBox.Show("Failed to insert image into database");
}
conn.Close();
B、将数据库中的图片读出来的代码片断：（完整DEMO程序见附录二）
try{
SqlConnection conn=new SqlConnection("Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=DatabaseImage;Data Source=(local)");
conn.Open();
SqlCommand comm=conn.CreateCommand();
comm.CommandText="select * from Images where ;
comm.CommandType=CommandType.Text;
comm.Parameters.Add("@id", SqlDbType.BigInt).Value=int.Parse(Request["id"]);
SqlDataReader reader=comm.ExecuteReader();
while(reader.Read())
{
Response.ContentType=reader["contentType"].ToString();
Response.BinaryWrite((byte[])reader["Image"]);
}
Response.End();
conn.Close();
}
catch
{
Response.End();
}
这段代码可置于Page_Load事件中，数据图片要注意的两点是：
一、 设置正确的ContentType（http中的content-type），图片的content-type格式一般为image/*，如jpeg为image/jpeg，bmp为image/bmp等等。
二、 仅仅输出一张图片二进制流，asp.net 中Page_Load事件先于页面输出被触发，因此图片的输出可以在此事件中进行，直接操作Reponse对象，避免输出与图片无关的而外信息（额外的第二张图片或者文字）。图片的二进制流输出后及时使用Response.End()方法结束http响应，避免页面中的额外信息被asp.net的引擎默认输出到客户端。
附录一：
MainForm.cs
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.IO;
using System.Windows.Forms;
namespace InsertImageToDatabase
{
public class MainForm : System.Windows.Forms.Form
{
private System.Windows.Forms.OpenFileDialog openFileDlg;
private System.Windows.Forms.TextBox filePath;
private System.Windows.Forms.Button browseButton;
private System.Windows.Forms.Button insertButton;
///
/// Required designer variable.
///
private System.ComponentModel.Container components = null;
public MainForm()
{
//
// Required for Windows Form Designer support
//
InitializeComponent();
//
// TODO: Add any constructor code after InitializeComponent call
//
}
///
/// Clean up any resources being used.
///
protected override void Dispose( bool disposing )
{
if( disposing )
{
if (components != null)
{
components.Dispose();
}
}
base.Dispose( disposing );
}
#region Windows Form Designer generated code
///
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
///
private void InitializeComponent()
{
this.openFileDlg = new System.Windows.Forms.OpenFileDialog();
this.filePath = new System.Windows.Forms.TextBox();
this.browseButton = new System.Windows.Forms.Button();
this.insertButton = new System.Windows.Forms.Button();
this.SuspendLayout();
//
// openFileDlg
//
this.openFileDlg.DefaultExt = "*.jpg;*.gif;*.bmp;*.png";
this.openFileDlg.Filter = "Image Files|*.jpg;*.gif;*.bmp;*.png|All Files|*.*";
//
// filePath
//
this.filePath.Location = new System.Drawing.Point(16, 16);
this.filePath.Name = "filePath";
this.filePath.ReadOnly = true;
this.filePath.Size = new System.Drawing.Size(168, 20);
this.filePath.TabIndex = 0;
this.filePath.Text = "";
//
// browseButton
//
this.browseButton.Location = new System.Drawing.Point(200, 16);
this.browseButton.Name = "browseButton";
this.browseButton.TabIndex = 1;
this.browseButton.Text = "&Browse";
this.browseButton.Click += new System.EventHandler(this.browseButton_Click);
//
// insertButton
//
this.insertButton.Enabled = false;
this.insertButton.Location = new System.Drawing.Point(200, 56);
this.insertButton.Name = "insertButton";
this.insertButton.TabIndex = 2;
this.insertButton.Text = "&Insert";
this.insertButton.Click += new System.EventHandler(this.insertButton_Click);
//
// MainForm
//
this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
this.ClientSize = new System.Drawing.Size(292, 273);
this.Controls.Add(this.insertButton);
this.Controls.Add(this.browseButton);
this.Controls.Add(this.filePath);
this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedSingle;
this.MaximizeBox = false;
this.Name = "MainForm";
this.Text = "Insert Image to Database";
this.ResumeLayout(false);
}
#endregion
///
/// The main entry point for the application.
///
[STAThread]
static void Main()
{
Application.Run(new MainForm());
}
private void browseButton_Click(object sender, System.EventArgs e)
{
if(openFileDlg.ShowDialog()==DialogResult.OK)
{
filePath.Text=openFileDlg.FileName;
insertButton.Enabled=true;
}
}
private void insertButton_Click(object sender, System.EventArgs e)
{
FileStream fs=File.OpenRead(filePath.Text);
byte[] content=new byte[fs.Length];
fs.Read(content, 0,content.Length);
fs.Close();
SqlConnection conn=new SqlConnection("Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=DatabaseImage;Data Source=(local)");
conn.Open();
SqlCommand comm=conn.CreateCommand();
comm.CommandText="insert into Images(Image, contentType) values(@image, @contentType)";
comm.CommandType=CommandType.Text;
SqlParameter param=comm.Parameters.Add("@image", SqlDbType.Image);
param.Value=content;
comm.Parameters.Add("@contentType", SqlDbType.NVarChar).Value=
GetContentType(new FileInfo(filePath.Text).Extension.Remove(0,1));
if(comm.ExecuteNonQuery()==1)
{
MessageBox.Show("Successfully insert image into database!");
}
else
{
MessageBox.Show("Failed to insert image into database");
}
conn.Close();
}
private string GetContentType(string extension)
{
string type="jpeg";
if(extension=="jpg")
{
type="jpeg";
}else
{
type=extension;
}
return "image/"+type;
}
}
}
附录二：
ReadImage.aspx
<％@ Page language="c#" Codebehind="ReadImage.aspx.cs" AutoEventWireup="false" Inherits="ReadImage.ReadImage"％>
ReadImage.aspx.cs
using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
namespace ReadImage
{
///
/// Summary description for ReadImage.
///
public class ReadImage : System.Web.UI.Page
{
private void Page_Load(object sender, System.EventArgs e)
{
try{
SqlConnection conn=new SqlConnection("Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=DatabaseImage;Data Source=(local)");
conn.Open();
SqlCommand comm=conn.CreateCommand();
comm.CommandText="select * from Images where id>@id";
comm.CommandType=CommandType.Text;
comm.Parameters.Add("@id", SqlDbType.BigInt).Value=int.Parse(Request["id"]);
SqlDataReader reader=comm.ExecuteReader();
while(reader.Read())
{
Response.ContentType=reader["contentType"].ToString();
Response.BinaryWrite((byte[])reader["Image"]);
}
Response.Write("aaaaaa");
Response.End();
conn.Close();
}
catch
{
Response.End();
}
}
#region Web Form Designer generated code
override protected void OnInit(EventArgs e)
{
//
// CODEGEN: This call is required by the ASP.NET Web Form Designer.
//
InitializeComponent();
base.OnInit(e);
}
///
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
///
private void InitializeComponent()
{
this.Load += new System.EventHandler(this.Page_Load);
}
#endregion
}
}