正在使用处理程序从数据库检索图像
本文关键字：数据库 检索 图像 程序 处理 | 更新日期: 2023-09-27 18:04:21
对于一个学校项目，我必须创建一个网店。我正试图从数据库中取出产品图像，但似乎无法正常工作我在网上读到，你应该通过一个处理人员来完成就是这个：
public class afbeelding : IHttpHandler
{
public void ProcessRequest(HttpContext context)
{
//Connect
string connectionstring = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:'Users'jeroen'Documents'Visual Studio 2010'Projects'producten'producten'App_Data'Bimsports.accdb;Persist Security Info=True";
OleDbConnection conn = new OleDbConnection(connectionstring);
//execute
int artikelnummer = 1;
string sql = "SELECT foto FROM Artikel WHERE Artikelnummer =?";
OleDbCommand cmd = new OleDbCommand(sql, conn);
cmd.Parameters.AddWithValue("Artikelnummer", artikelnummer);
//read
try
{
conn.Open();
OleDbDataReader reader = cmd.ExecuteReader();
reader.Read();
context.Response.BinaryWrite((byte[])reader["foto"]);
}
catch
{
}
finally
{
conn.Close();
}
我应该把这个放在aspx:中
<asp:Image ID="img_nikeshirt" runat="server" ImageUrl='<%# "afbeelding.ashx?ID=" + Eval("artikelnummer")%>'/>
我没有错误，但图像不会显示。有人能帮我吗？
编辑：
顺便说一下，图像在访问数据库中。上面写着ole对象。它仍然被认为是图像吗？
另一个编辑：
如果我直接将查询放入access，它会给我图片的列，而不是图片本身。。。这会是问题所在吗？如果是，我该如何修复？
您是否尝试返回HTTP响应消息？
而不是void返回byte[]的上下文
您应该在响应上设置内容类型标题，如下所示：
context.Response.ContentType = "image/png";
context.Response.BinaryWrite((byte[])reader["foto"]);
context.Response.Flush();
我得到了它，伙计们发现我丢失了很多代码，出于某种原因，通过访问保存图像本身不起作用。相反，我制作了一个页面，将其加载到那里。对于有同样问题的人，这里是我的代码。
将图像保存在数据库中的网络表单
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
</div>
<asp:DropDownList ID="ddlartikel" runat="server" AutoPostBack="true"
onselectedindexchanged="ddlartikel_SelectedIndexChanged">
</asp:DropDownList>
<br />
<asp:Image ID="imgfoto" runat="server" />
<p>Verander Foto's</p>
<asp:FileUpload ID="FileUpload1" runat="server" />
<br />
<asp:Button ID="btnsave" runat="server" Text="Sla op in database"
onclick="btnsave_Click" />
</form>
</body>
</html>
将图像保存到数据库的网络表单背后的代码
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
//Connect
string connectionstring = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:'Users'jeroen'Documents'Visual Studio 2010'Projects'producten'producten'App_Data'Bimsports.accdb;Persist Security Info=True";
OleDbConnection conn = new OleDbConnection(connectionstring);
//Execute
string sql = "SELECT Artikelnummer, Omschrijving FROM Artikel";
OleDbCommand cmd = new OleDbCommand(sql, conn);
//Read
try
{
conn.Open();
OleDbDataReader reader = cmd.ExecuteReader();
ddlartikel.DataSource = reader;
ddlartikel.DataValueField = "artikelnummer";
ddlartikel.DataTextField = "omschrijving";
ddlartikel.DataBind();
}
finally{conn.Close();}
FetchPicture();
}
}
protected void ddlartikel_SelectedIndexChanged(object sender, EventArgs e)
{
FetchPicture();
}
private void FetchPicture()
{
if (ddlartikel.SelectedIndex > -1)
{
int artikelnummer = Convert.ToInt32(ddlartikel.SelectedValue);
string sUrl = string.Format("~/afbeelding.ashx?artikelnummer={0}", artikelnummer);
imgfoto.ImageUrl = sUrl;
}
}
protected void btnsave_Click(object sender, EventArgs e)
{
if (FileUpload1.HasFile)
{
byte[] MyData = FileUpload1.FileBytes;
int artikelnummer = Convert.ToInt32(ddlartikel.SelectedValue);
CBlob.SavePicture(artikelnummer, MyData);
}
}
}
}
用于从数据库(您的网页(中检索图像的网络表单
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
Merk:
<asp:Label ID="lbl_merk" runat="server"></asp:Label>
<br />
Maat:
<asp:Label ID="lbl_maat" runat="server"></asp:Label>
<br />
Omschrijving:
<asp:Label ID="lbl_omschrijving" runat="server"></asp:Label>
<br />
<asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
Kleur:
<asp:Label ID="lbl_kleur" runat="server"></asp:Label>
<br />
Prijs:
<asp:Label ID="lbl_prijs" runat="server"></asp:Label>
<br />
BTW:
<asp:Label ID="lbl_btw" runat="server"></asp:Label>
<br />
Categorie:
<asp:Label ID="lbl_categorie" runat="server"></asp:Label>
<br />
<br />
<asp:Image ID="img_nikeshirt" runat="server" ImageUrl='<%# "afbeelding.ashx?ID=" + Eval("artikelnummer")%>'/>
</div>
</form>
</body>
</html>
网页后面的代码
protected void Page_Load(对象发送方，EventArgs e({int artikelnummer=1；//Connectstring connectionstring=@"Provider=Microsoft.ACE.OLEDB.12.0；数据源=C:''Users''jeroen''Documents''Visual Studio 2010''Projects''producten''producten''App_Data''Bimsports.accdb；持久安全信息=True"；OleDbConnection conn=新的OleDb连接(连接字符串(；
//Execute
string sql = "SELECT Merk, Maat, Omschrijving, Kleur, Prijs, BTW, Categorie.Categorie FROM Artikel INNER JOIN Categorie ON Artikel.Categorie = Categorie.Categorienummer WHERE Artikelnummer =?";
OleDbCommand cmd = new OleDbCommand(sql, conn);
cmd.Parameters.AddWithValue("Artikelnummer", artikelnummer);
//Read
try
{
conn.Open();
OleDbDataReader reader = cmd.ExecuteReader();
while (reader.Read())
{
lbl_merk.Text = reader["Merk"].ToString();
lbl_maat.Text = reader["Maat"].ToString();
lbl_omschrijving.Text = reader["Omschrijving"].ToString();
lbl_kleur.Text = reader["Kleur"].ToString();
lbl_prijs.Text = reader["Prijs"].ToString();
lbl_btw.Text = reader["BTW"].ToString();
lbl_categorie.Text = reader["Categorie"].ToString();
}
string sUrl = string.Format("~/afbeelding.ashx?artikelnummer={0}", artikelnummer);
img_nikeshirt.ImageUrl = sUrl;
}
catch
{
}
finally
{
conn.Close();
}
}
然后我创建了一个类，查看您请求的数据库中的图像，并将其放入字节[]中
public static byte[] getpicture(int artikelnummer)
{
string connectionstring = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:'Users'jeroen'Documents'Visual Studio 2010'Projects'producten'producten'App_Data'Bimsports.accdb;Persist Security Info=True";
OleDbConnection conn = new OleDbConnection(connectionstring);
//Execute
string sql = "SELECT foto FROM Artikel WHERE Artikelnummer =?";
OleDbCommand cmd = new OleDbCommand(sql, conn);
cmd.Parameters.AddWithValue("Artikelnummer", artikelnummer);
try
{
byte[] photodata = null;
conn.Open();
OleDbDataReader reader = cmd.ExecuteReader();
if (reader.HasRows)
{
reader.Read();
if (!reader.IsDBNull(0))
{
photodata = new byte[Convert.ToInt32((reader.GetBytes(0, 0, null, 0, Int32.MaxValue)))];
long bytesreceived = reader.GetBytes(0, 0, photodata, 0, photodata.Length);
}
}
return photodata;
}
catch (Exception ex)
{
}
finally
{
conn.Close();
}
return null;
}
public static bool SavePicture(int artikelnummer, byte[] photodata)
{
int rowupdated = 0;
string connectionstring = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:'Users'jeroen'Documents'Visual Studio 2010'Projects'producten'producten'App_Data'Bimsports.accdb;Persist Security Info=True";
OleDbConnection conn = new OleDbConnection(connectionstring);
string sql = "UPDATE Artikel SET foto=? WHERE artikelnummer=?";
OleDbCommand cmd = new OleDbCommand(sql, conn);
conn.Open();
OleDbParameter param = new OleDbParameter("@foto", OleDbType.VarBinary, photodata.Length);
param.Value = photodata;
cmd.Parameters.Add(param);
cmd.Parameters.AddWithValue("Artikelnummer", artikelnummer);
rowupdated = (int)cmd.ExecuteNonQuery();
return (rowupdated>0);
}
}
}
并且处理程序正在将其写入页面。
public class afbeelding : IHttpHandler
{
public void ProcessRequest(HttpContext context)
{
int artikelnummer = 0;
if (context.Request.QueryString["artikelnummer"] != null)
{
artikelnummer = int.Parse(context.Request.QueryString["artikelnummer"]);
}
if (artikelnummer != 0)
{
byte[] bytes = CBlob.getpicture(artikelnummer);
if (bytes != null)
{
context.Response.ContentType = "image/jpeg";
context.Response.OutputStream.Write(bytes, 0, bytes.Length);
}
}
}
public bool IsReusable
{
get
{
return false;
}
}
}
它可能会做得更容易、更短，但嘿，它有效！感谢的所有输入
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