Example development: ASP. NET Create a network album

In the digital age, we often take pictures for souvenir, and with the increase of digital photos, it is often necessary to manage these photos well so as to better consult the souvenir. Now there are a lot of electronic albums online, can be very good to achieve these functions, then we can create their own albums it? Of course, in this article, we will use ASP.net to create a simple online album to collect our photos.

First let's look at the features of this album. In this album, we must first put the photos of the photo into a directory, after which you can use the online "last, next" link to a sheet of view.

Here's how to get a picture in a folder. We can use the DirectoryInfo class in the System.IO namespace to implement it. The path where the folder is located is passed as a parameter to the constructor of the class, and an instance of the DirectoryInfo class is declared. The DirectoryInfo class has a GetFiles () method that returns an array of FileInfo objects, and each instance of FileInfo contains specific information about the file under the specified path. The following code fragment illustrates the process:

The following are the referenced contents: Sub Page_Load (sender as Object, E as EventArgs) ' Get list of images Dim Dirinfo as New DirectoryInfo (Server.MapPath ("")) Dim images () as FileInfo = Filterforimages (Dirinfo.getfiles ()) ... End Sub

Where the path to the current directory is obtained with Server.MapPath, and Dirinfo.getfiles () returns all the files in that directory. And because we are albums, just want to see such as jpg,bmp,gif image files, so we can implement the program, loading only these types of files, this through a custom process filterforimages to implement, the process will only return the specified folder image type of files. The code is as follows:

The following are the referenced contents: Function filterforimages (Images () as FileInfo) as FileInfo () Dim newimages as New ArrayList (images. Length) Dim I as Integer For i = 0 to images. Length-1 If path.getextension (Images (i). Name) = ". jpg" OrElse _ Path.getextension (Images (i). Name) = ". Jpeg" OrElse _ Path.getextension (Images (i). Name) = ". png" OrElse _ Path.getextension (Images (i). Name) = ". gif" Then Newimages.add (Images (i)) End If Next Return CType (Newimages.toarray (GetType (FileInfo)), FileInfo ()) End Function

This procedure traverses the FileInfo parameter array passed in, betrays the suffix name of the file in the folder, and if it belongs to the image file, adds it to the Newimages array and returns in ArrayList form.

Next, we'll look at how to display each picture and show it as "last, next." To know how many pictures are currently being browsed, you can do this by using the method of passing parameters. First add an image control and text box to the form, with the following program code:

Sub Page_Load (sender as Object, E as EventArgs)
...

' Dim imgindex as Integer = 0
If not Request.QueryString ("N") are nothing AndAlso _
IsNumeric (Request.QueryString ("N")) Then
Imgindex = CInt (Request.QueryString ("N"))
End If
　
Currentimgtitle.text = "You are viewing:" & _
Path.getfilenamewithoutextension (Images (imgindex). Name) & _
"(" & Imgindex + 1 & "of" & images. Length & ")"
Currentimg.imageurl = Path.getfilename (Images (imgindex). Name)
...
End Sub

HTML Part Code

In the above code, the variable imgindex is used to indicate the current browsing is the first few pictures, at the beginning of the n=0, you get the images array, the first variable, and then each time you read the variable value, you can know the current browsing is the first few pictures.

To achieve the "next, previous" feature, add two hyperlink link controls to the form, adding the following code

The following are the referenced contents: Sub Page_Load (sender as Object, E as EventArgs) ... If Imgindex > 0 Then Lnkprev.navigateurl = "default.aspx?" N= "& ImgIndex-1 End If If Imgindex, images. Length-1 Then Lnknext.navigateurl = "default.aspx?" N= "& Imgindex + 1 End If ... End Sub

HTML Part Code

The following are the referenced contents: |

The above code is easier to understand, when the next one, the previous link, the value of the parameter n plus 1, or minus 1.

Finally, in order to achieve a more intuitive effect, we place a DataList control, which displays all the files under the Image folder, and each time a new picture is browsed, the name of the picture currently being browsed is highlighted in the form of a link with the following code:

The following are the referenced contents: Sub Page_Load (sender as Object, E as EventArgs) ... Dlindex.datasource = Images Dlindex.databind () End Sub Sub Dlindex_itemdatabound (sender as Object, E as DataListItemEventArgs) If E.item.itemtype = ListItemType.Item OrElse _ E.item.itemtype = ListItemType.AlternatingItem Then ' Get the Hyperlink Dim hl as HyperLink = CType (E.item.findcontrol ("Lnkpic"), HyperLink) ' Set the Text and navigation properties hl. Text = Path.getfilenamewithoutextension (_ DataBinder.Eval (e.Item.DataItem, "Name"). ToString ()) & _ "(" & _ Int (DataBinder.Eval (e.Item.DataItem, "Length")/1000) & _ "KB") hl. NavigateUrl = "default.aspx?" N= "& E.item.itemindex End If End Sub

HTML Part Code

The following are the referenced contents: Repeatcolumns= "3" >

In the above code, in the DataList Onitemdatabound event, first determine whether the currently triggered item is a list item ListItemType or an alternating item alternatingitem, and if so, dynamically generate a link HL, Sets the value of HL to the name of the file that is currently browsing the image. And note the size of the file, set its link to the address of the current browse image address, so that users can directly point to browse the picture, not to pass the previous one, the next link to achieve.

Finally give an example of running and all the code:

The following are the referenced contents: <%@ Import namespace= "System.IO"%> Dim Imgindex as Integer = 0 If not Request.QueryString ("n") are nothing AndAlso isnumeric (Request.QueryString ("n")) then Imgindex = CInt (Request.QueryString ("N")) End If Currentimgtitle.text = "You are viewing:" & _ Path.getfilenamewithoutextension (Images (imgindex). Name) & _ "(" & Imgindex + 1 & "of" & images. Length & ")" Currentimg.imageurl = Path.getfilename (Images (imgindex). Name) If Imgindex > 0 Then Lnkprev.navigateurl = "default.aspx?" N= "& ImgIndex-1 End If If Imgindex, images. Length-1 Then Lnknext.navigateurl = "default.aspx?" N= "& Imgindex + 1 End If Dlindex.datasource = Images Dlindex.databind () End Sub Function filterforimages (Images () as FileInfo) as FileInfo () Dim newimages as New ArrayList (images. Length) Dim I as Integer For i = 0 to images. Length-1 If path.getextension (Images (i). Name) = ". jpg" OrElse _ Path.getextension (Images (i). Name) = ". Jpeg" OrElse _ Path.getextension (Images (i). Name) = ". png" OrElse _ Path.getextension (Images (i). Name) = ". gif" Then Newimages.add (Images (i)) End If Next Return CType (Newimages.toarray (GetType (FileInfo)), FileInfo ()) End Function Sub Dlindex_itemdatabound (sender as Object, E as DataListItemEventArgs) If E.item.itemtype = ListItemType.Item OrElse e.item.itemtype = ListItemType.AlternatingItem Then Dim hl as HyperLink = CType (E.item.findcontrol ("Lnkpic"), HyperLink) hl. Text = Path.getfilenamewithoutextension (DataBinder.Eval (e.Item.DataItem, "Name"). ToString ()) & _ "(" & Int (DataBinder.Eval (e.Item.DataItem, Length)/1000) & "KB" hl. NavigateUrl = "default.aspx?" N= "& E.item.itemindex End If End Sub | repeatcolumns= "3" cssclass= "index" >