Question

这是我显示图片的代码：

<asp:image ID="Image3" runat="server" ImageUrl="AyoBelajar_Angka.aspx?id_bahan=7">

这是我的代码隐藏：

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    If Request.QueryString("id_bahan") IsNot Nothing Then
        Dim strQuery As String = "select nama,kategori, gambar from ayobelajar where id_bahan=@id_bahan"
        Dim cmd As SqlCommand = New SqlCommand(strQuery)
        cmd.Parameters.Add("@id_bahan", SqlDbType.VarChar).Value() = Convert.ToInt32(Context.Request.QueryString("id_bahan"))
        Dim dt As DataTable = GetData(cmd)
        Dim bytes() As Byte = CType(dt.Rows(0)("gambar"), Byte())
        Response.Buffer = True
        Response.Charset = ""
        Response.Cache.SetCacheability(HttpCacheability.NoCache)
        Response.ContentType = dt.Rows(0)("kategori").ToString()
        Response.AddHeader("content-disposition", "attachment;filename=" + dt.Rows(0)("nama").ToString())
        Response.BinaryWrite(bytes)
        Response.Flush()
        Response.End()

Answer 1

将您的字节数组转换为base64String字符串，然后将其分配给您的图像控件。

 Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    If Request.QueryString("id_bahan") IsNot Nothing Then
        Dim strQuery As String = "select nama,kategori, gambar from ayobelajar where id_bahan=@id_bahan"
        Dim cmd As SqlCommand = New SqlCommand(strQuery)
        cmd.Parameters.Add("@id_bahan", SqlDbType.VarChar).Value() = Convert.ToInt32(Context.Request.QueryString("id_bahan"))
        Dim dt As DataTable = GetData(cmd)
        Dim bytes() As Byte = CType(dt.Rows(0)("gambar"), Byte())
        'Converting Byte array to ToBase64String  
        Dim base64String As String = Convert.ToBase64String(bytes, 0, bytes.Length)
        Image3.ImageUrl = "data:image/png;base64," & base64String
 End Sub

Answer 2

从你的代码隐藏中看来，你的图像被保存为byte数组而不是字符串。您发布的代码隐藏不返回字符串，它返回二进制数据，并且不能放在需要字符串的ImageUrl属性中。

您可以将图像二进制数据转换为Base64String，然后将其放入ImageUrl属性中。转换非常简单：

Dim ImageString As String = Convert.ToBase64String(bytes, 0, bytes.Length)

但是，您必须在字符串前面添加图像类型。如果您的所有图像都是相同的类型，那么让我们说jpg文件，然后这很容易：

ImageString = "data:image/jpg;base64," & ImageString

但是如果数据库中有不同类型的图像，则必须从二进制数据中检测图像的类型。 Here is how you can do so。但似乎你有dt.Rows(0)("kategori").ToString()中的类型？

最后，你需要返回字符串，所以这里是完整的代码（将jpg改为你的图像类型）：

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    If Request.QueryString("id_bahan") IsNot Nothing Then
        Dim strQuery As String = "select nama,kategori, gambar from ayobelajar where id_bahan=@id_bahan"
        Dim cmd As SqlCommand = New SqlCommand(strQuery)
        cmd.Parameters.Add("@id_bahan", SqlDbType.VarChar).Value() = Convert.ToInt32(Context.Request.QueryString("id_bahan"))
        Dim dt As DataTable = GetData(cmd)
        Dim bytes() As Byte = CType(dt.Rows(0)("gambar"), Byte())
        Dim ImageString As String = Convert.ToBase64String(bytes, 0, bytes.Length)
        ImageString = "data:image/jpg;base64," & ImageString
        Response.Clear()
        Response.Buffer = True
        Response.Charset = ""
        Response.Cache.SetCacheability(HttpCacheability.NoCache)
        Response.ContentType = "text/plain"
        Response.Write(ImageString)
        Response.End()
    Else
        'I don't know what code you have here
    End If
End Sub

Answer 3

嗨，你要在数据库中有一个想要显示该图像的图像路径。您可以将其转换为ToBase64String格式并显示，也可以直接完成。如果你的路径是正确的。

/(\d{4}\/[^ ]+) \K([\d:]+)/

查看

 Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    'From database get path and assign to imagePath variable 
    Dim imagePath As String = "~/Files/happy.jpg"
    Dim filePath As String = Server.MapPath(imagePath)
    ' Will Convert filePath to bytes
    Dim imageBytes As Byte() = File.ReadAllBytes(filePath)
    'bytes array to ToBase64String 
    Dim base64String As String = Convert.ToBase64String(imageBytes, 0, imageBytes.Length)
    'Attaching image to ToBase64String 
    Image3.ImageUrl = "data:image/jpg;base64," & base64String
End Sub

输出

文件夹视图

如何在ASP.Net中从字符串类型的数据库中调用图像？

3 个答案: