This is a partial implementation of the XOM library by by Elliotte Rusty Harold.
The library implements all XOM read methods, it's also possible to write XML using this library but not all XOM write methods have (so far) been implemented.
So with B4A we have the existing XmlSax parser which is what's know as a push parser.
XmlSax will parse an XML document from start to end and generate an event each time it finds a start or end element.
XOM let's you access an XML document using DOM methods.
You can access any elements in any order with no requirement to parse the entire document first.
The library has abstract objects that represent various XML elements - you work with objects such as XOMAttribute and XOMNode.
A code example explains it better:
The example creates an XOMDocument from a String obtained from a file in Assets.
It extracts the 'current_condition' element and then the 'weather' elements.
These elements are saved as Global XOMElement and XOMElements objects, the rest of the XOMDocument is discarded.
XOM can build an XOMDocument from File, InputStream and Url as well as from a String.
Use of the BuildFromURL method requires android.permission.INTERNET.
XOM does NOT automatically enable this permission, so if you use BuildFromUrl you must ensure that your application has this permission enabled.
I decided this was better than automatically enabling the internet permission - if you do not use BuildFromUrl then your application will not enable an unnecessary permission.
Use of XOM requires two additional jar files to be added to your B4A additional libraries folder: xom-1.2.10.jar and dtd-xercesImpl.jar, the forum attachment size limit prevents me from attaching these two files to this post so i have made them available from here.
I am not actively developing this library, it's an old project that i have uploaded to enable another forum member to extract data from an HTML webpage.
I'll fix any bugs but do not plan to implement any new features.
Source code is available on request if any other forum members want to further develop or modify the library.
Martin.
XOM™ is a new XML object model. It is an open source (LGPL), tree-based API for processing XML with Java that strives for correctness, simplicity, and performance, in that order.
The library implements all XOM read methods, it's also possible to write XML using this library but not all XOM write methods have (so far) been implemented.
So with B4A we have the existing XmlSax parser which is what's know as a push parser.
XmlSax will parse an XML document from start to end and generate an event each time it finds a start or end element.
XOM let's you access an XML document using DOM methods.
You can access any elements in any order with no requirement to parse the entire document first.
The library has abstract objects that represent various XML elements - you work with objects such as XOMAttribute and XOMNode.
A code example explains it better:
B4X:
Sub Process_Globals
End Sub
Sub Globals
Dim CurrentCondition As XOMElement
Dim DateSpinner As Spinner
Dim MinTempLabel As Label
Dim MaxTempLabel As Label
Dim PrecipitationLabel As Label
Dim WeatherDescLabel As Label
Dim WeatherElements As XOMElements
Dim WindDirectionLabel As Label
Dim WindSpeedLabel As Label
End Sub
Sub Activity_Create(FirstTime As Boolean)
Activity.LoadLayout("Main")
Dim XOMBuilder1 As XOMBuilder
XOMBuilder1.Initialize("XOMBuilder1")
' the BuildFromString method is used here as the BuildFromFile method cannot access files in assets
Dim XmlString As String=File.GetText(File.DirAssets, "weather.xml")
XOMBuilder1.BuildFromString(XmlString, "", Null)
End Sub
Sub Activity_Resume
End Sub
Sub Activity_Pause (UserClosed As Boolean)
End Sub
Sub DateSpinner_ItemClick (Position As Int, Value As Object)
If Position=0 Then
MaxTempLabel.Text="Temp: "&CurrentCondition.GetFirstChildElementByName("temp_C").Value&"C"
MinTempLabel.Text="Time: "&CurrentCondition.GetFirstChildElementByName("observation_time").Value
PrecipitationLabel.Text="Precipitation: "&CurrentCondition.GetFirstChildElementByName("precipMM").Value&"mm"
WeatherDescLabel.Text="Summary: "&CurrentCondition.GetFirstChildElementByName("weatherDesc").Value
WindDirectionLabel.Text="Wind direction: "&CurrentCondition.GetFirstChildElementByName("winddir16Point").Value
WindSpeedLabel.Text="Wind speed: "&CurrentCondition.GetFirstChildElementByName("windspeedMiles").Value&"mph"
Else
Dim SelectedWeatherElement As XOMElement
SelectedWeatherElement=WeatherElements.GetElement(Position-1)
MaxTempLabel.Text="Max temp: "&SelectedWeatherElement.GetFirstChildElementByName("tempMaxC").Value&"C"
MinTempLabel.Text="Min temp: "&SelectedWeatherElement.GetFirstChildElementByName("tempMinC").Value&"C"
PrecipitationLabel.Text="Precipitation: "&SelectedWeatherElement.GetFirstChildElementByName("precipMM").Value&"mm"
WeatherDescLabel.Text="Summary: "&SelectedWeatherElement.GetFirstChildElementByName("weatherDesc").Value
WindDirectionLabel.Text="Wind direction: "&SelectedWeatherElement.GetFirstChildElementByName("winddirection").Value
WindSpeedLabel.Text="Wind speed: "&SelectedWeatherElement.GetFirstChildElementByName("windspeedMiles").Value&"mph"
End If
End Sub
Sub XOMBuilder1_BuildDone(XOMDocument1 As XOMDocument, Tag As Object)
If XOMDocument1.IsInitialized Then
Log("XOMDocument is initialized")
Dim RootElement As XOMElement
RootElement=XOMDocument1.RootElement
DateSpinner.Add("Current conditions")
CurrentCondition=RootElement.GetFirstChildElementByName("current_condition")
WeatherElements=RootElement.GetChildElementsByName("weather")
Dim i, WeatherElementsCount As Int
WeatherElementsCount=WeatherElements.Size
For i=0 To WeatherElementsCount-1
DateSpinner.Add(WeatherElements.GetElement(i).GetFirstChildElementByName("date").Value)
Next
DateSpinner.Enabled=True
DateSpinner_ItemClick(0, Null)
Else
' XOMDocument1 will be uninitialized if an error has occurred
Log("An error has occured and the XOMDocument has NOT been initialized")
Log(LastException.Message)
End If
End SubThe example creates an XOMDocument from a String obtained from a file in Assets.
It extracts the 'current_condition' element and then the 'weather' elements.
These elements are saved as Global XOMElement and XOMElements objects, the rest of the XOMDocument is discarded.
XOM can build an XOMDocument from File, InputStream and Url as well as from a String.
Use of the BuildFromURL method requires android.permission.INTERNET.
XOM does NOT automatically enable this permission, so if you use BuildFromUrl you must ensure that your application has this permission enabled.
I decided this was better than automatically enabling the internet permission - if you do not use BuildFromUrl then your application will not enable an unnecessary permission.
Use of XOM requires two additional jar files to be added to your B4A additional libraries folder: xom-1.2.10.jar and dtd-xercesImpl.jar, the forum attachment size limit prevents me from attaching these two files to this post so i have made them available from here.
I am not actively developing this library, it's an old project that i have uploaded to enable another forum member to extract data from an HTML webpage.
I'll fix any bugs but do not plan to implement any new features.
Source code is available on request if any other forum members want to further develop or modify the library.
Martin.
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