在中继器控件上显示图像

发布于 2024-12-08 14:12:17 字数 1061 浏览 3 评论 0原文

使用 C# ASP.NET。我在中继器控制方面遇到问题。我想在存储在数据库中的页面上显示图像。我从 Northwind 数据库收集信息。

类别表

SQL语法：

CREATE TABLE [dbo].[Categories](
    [CategoryID] [int] IDENTITY(1,1) NOT NULL,
    [CategoryName] [nvarchar](15) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL,
    [Description] [ntext] COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
    [Picture] [image] NULL)

页面加载时C#语法：

 NorthWindDataContext db = new NorthWindDataContext();
            List<Category> oList = new List<Category>();
            oList = db.Categories.ToList();
            Repeater1.DataSource = oList;

aspx语法：

 <ItemTemplate>
            <tr>
                <td>
                   <%#DataBinder.Eval(Container, "DataItem.Picture")%>
                </td>

            </tr>
        </ItemTemplate>

运行代码后，在我的页面中没有得到图片。帮助我在我的页面上获取图片。提前致谢。如果有任何疑问，请询问。

原文

Work on C# ASP.NET. I have a problem with repeater control. I want to show images on a page that is stored in a database. I collect information from northwind database.

Categories table

SQL syntax:

CREATE TABLE [dbo].[Categories](
    [CategoryID] [int] IDENTITY(1,1) NOT NULL,
    [CategoryName] [nvarchar](15) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL,
    [Description] [ntext] COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
    [Picture] [image] NULL)

On pageload C# syntax :

 NorthWindDataContext db = new NorthWindDataContext();
            List<Category> oList = new List<Category>();
            oList = db.Categories.ToList();
            Repeater1.DataSource = oList;

aspx Syntax:

 <ItemTemplate>
            <tr>
                <td>
                   <%#DataBinder.Eval(Container, "DataItem.Picture")%>
                </td>

            </tr>
        </ItemTemplate>

After run the code,in my page i don't get the picture.help me to get picture on my page .Thanks in advance .If have any query plz ask.

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情魔剑神 2024-12-15 14:12:17

您将图像作为二进制数据存储在数据库中，因此无法按原样显示它。

MSDN 关于 image 数据类型：

从 0 到 2^31-1 的可变长度二进制数据 (2,147,483,647)
字节。

常见的方法是从内存流创建 System.Drawing.Image 的实例，然后将其显式写入响应中。此功能应由 ASHX 处理程序包装。参见intrawebs 的例子，有很多。

下面的处理程序伪代码：（然后在 ASPX 中只是引用处理程序）

IEnuemrable<byte> binaryImageData = queryExecutor.GetImageData(imageId);

// do not forget to dispose or use 'using'
var memoryStream = new MemoryStream(); 
memoryStream.Write(imageByte, 0, binaryImageData.Length);
System.Drawing.Image image = System.Drawing.Image.FromStream(memoryStream);

// ... create JPEG

context.Response.ContentType = "image/jpeg";
jpegImage.Save(context.Response.OutputStream, 
               System.Drawing.Imaging.ImageFormat.Jpeg);

我发现的好例子：

You are store images as binary data in a data base so you can not show it as is.

MSDN on image data type:

Variable-length binary data from 0 through 2^31-1 (2,147,483,647)
bytes.

The common approach is to create instance of the System.Drawing.Image from a memory stream and then write it explicitly inr response. This functionality should be wrapped by ASHX handler. See intrawebs for the examples, there are a lot.

Handler pseudo code below: (then in ASPX just reffer handler)

IEnuemrable<byte> binaryImageData = queryExecutor.GetImageData(imageId);

// do not forget to dispose or use 'using'
var memoryStream = new MemoryStream(); 
memoryStream.Write(imageByte, 0, binaryImageData.Length);
System.Drawing.Image image = System.Drawing.Image.FromStream(memoryStream);

// ... create JPEG

context.Response.ContentType = "image/jpeg";
jpegImage.Save(context.Response.OutputStream, 
               System.Drawing.Imaging.ImageFormat.Jpeg);

Good examples I've found:

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