Creating the Main Form (Visual Basic)

The main form provides the user interface for the JumpStart application and consists of four elements.

Interface Element	Description
Text1	A text box for entering the file name of the file to parse.
Command1	A button to start the parse process.
Command2	A button to exit the application.
Text2	A text box that displays the results of the parse operation.

In addition to providing the interface elements, the main form also provides code that creates the required instances of the classes and starts the parse process.

To	The main form uses this code
Create a new instance of the reader (`SAXXMLReader40`)	`Dim reader As New SAXXMLReader40`
Create an instance of `ContentHandlerImpl` and set it to receive events from the reader	`Dim contentHandler As New ContentHandlerImpl` `Set reader.contentHandler = contentHandler`
Create an instance of `ErrorHandlerImpl` and set it to receive events from the reader	`Dim errorHandler As New ErrorHandlerImpl` `Set reader.errorHandler = errorHandler`
Create an instance of `DTDHandlerImpl` and set it to receive events from the reader	`Dim dtdHandler As New DTDHandlerImpl` `Set reader.dtdHandler = dtdHandler`
Start the parse process	`reader.parseURL (txtFilePath.Text)`

Complete Code for the Main Form

The following is the complete code for the main form of the JumpStart application.

Private Sub cmdBrowse_Click()
    CommonDialog1.ShowOpen
    txtFilePath.Text = CommonDialog1.FileName
End Sub

Private Sub cmdExit_Click()
    End
End Sub

Private Sub cmdParse_Click()
    Dim reader As New SAXXMLReader40             'Reads the XML document
    Dim contentHandler As New ContentHandlerImpl 'Receives parsing events
    Dim errorHandler As New ErrorHandlerImpl     'Receive error events
    Dim dtdHandler As New DTDHandlerImpl
    rtfOutput.Text = ""
    Set reader.contentHandler = contentHandler   'They work together
    Set reader.errorHandler = errorHandler       'They also work together
    Set reader.dtdHandler = dtdHandler
    On Error GoTo 10
    reader.parseURL (txtFilePath.Text)           'Parse the document

    Exit Sub                                     'That's all, folks!

10: rtfOutput.Text = rtfOutput.Text & "*** Error *** " & Err.Number _
      & " : " & Err.Description
End Sub

Private Sub Form_Load()
    Dim fso As New FileSystemObject
    Dim folder As folder
    Dim strSampleFilePath As String
    
    Set folder = fso.GetFolder(".")
    
    strSampleFilePath = fso.GetAbsolutePathName(folder.Path) & "\books.xml"

    frmMain.txtFilePath.Text = strSampleFilePath
    
End Sub

The Exit Sub and line marked 10: are required only if you want to handle processing outside the ErrorHandler. Otherwise, you can use On Error Resume Next.

The following instructions are based on the assumption that you will create a sample data file named "books.xml", however, you can use other XML documents as the input file for this application.

To run the JumpStart application

Save the project and then copy books.xml to the folder where you saved the project.
From the Visual Basic toolbar, click Start.
In the text box that displays the name and path to the input file, verify that the path for the books.xml file is valid and correct.
Note You should save a copy of this sample XML file in the same folder as your copy of the JumpStart project.
On the form, click Run.
If the application starts and runs successfully, the sample file will display as SAX parsed output in the results text box.
Click Exit to close the application when you are done running it.

This application is intended to provide a simple introduction to SAX2 (Simple API for XML) and serve as a starting point for writing your own SAX-based applications. For more information about the MSXML (Microsoft® XML Parser) implementation of the SAX2 interfaces, see the SAX Reference.

Creating the Main Form (Visual Basic)

Complete Code for the Main Form

See Also