Dynamic UI Generation in WebDynpro using xml-file

[Former Member]

hello all,

I'm trying to modify the Webdynpro Tutorial 17 "Dynamic UI Generation in WebDynpro" in the following way:

Instead of using the data stored in the SomeBackEnd.java Class, my program should read a xml-File on the initialization of the class.

public class ApplicationDescriptor {
/////////////////////////////////////////////////////////
	public class FieldDescriptor
	{
		private String uiType;
		private String contextName;
		private String contextType;
		private String label;
	
		
		public FieldDescriptor(String uiType, String contextName, String contextType, String label)
		{
			this.uiType = uiType;
			this.contextName = contextName;
			this.contextType = contextType;
			this.label = label;
		}
		
		String getUIType(){ return uiType; };
		String getContextName(){ return contextName; };
		String getContextType(){ return contextType; };
		String getLabel(){ return label; };
	}
	
	public class OperationDescriptor
	{
		private String actionName;
		private String displayText;
		
		public OperationDescriptor(String actionName, String displayText)
		{
			this.actionName = actionName;
			this.displayText = displayText;
		}
		
		String getActionName(){ return actionName; };
		String getDisplayText(){ return displayText;  };
	}
	private int fieldCount = 0;
	private int operationCount = 0;
	
/////////////////////////////////////////////////////////
public class HandelXML extends DefaultHandler
{

	private String thisSection = "";
	
	private String inputType = "";
	private String contextName = "";
	private String contextType = "";
	private String label = "";
	private String action = "";


	
	public HandelXML()
	{
	}
	
	public void startDocument() throws SAXException
	{
		fieldCount = 0;
		operationCount = 0;
	}
	
	public void startElement(String namespaceURI, String localName, String qName, org.xml.sax.Attributes atts) throws SAXException
	{
		thisSection = qName;
		
		if (qName.equals("input"))
		{
			inputType = "InputField";
		}
		
	}
	
	public void endElement(String namespaceURI, String localName, String qName) throws SAXException
	{
		if (qName.equals("input"))
		{
			fields[fieldCount] = new FieldDescriptor(inputType, contextName, contextType, label);
			fieldCount = fieldCount + 1;
			System.out.println("Field: " + inputType + "|" + contextName + "|" + contextType + "|" + label);
		}
		
		if (qName.equals("submit") || qName.equals("exit"))
		{
			operations[operationCount] = new OperationDescriptor(action, label);
			operationCount = operationCount + 1;
			System.out.println("Operation: " + action + "|" + label );
		}
	}
	
	public void characters(char[] ch, int start, int length) throws SAXException
	{
		String text=new String(ch, start, length);
		text=text.trim();
		if (text.length() > 0)
		{
			if (thisSection.equals("caption"))
			{
				label = text;
			}
			if (thisSection.equals("value"))
			{
				contextName = text;
			}
			if (thisSection.equals("type"))
			{
				contextType = text;
			}
			if (thisSection.equals("action"))
			{
				action = text;
			}
		}
	}
}
/////////////////////////////////////////////////////////

  	public ApplicationDescriptor()
  	{
		XMLReader xmlReader = null;
		
		try
		{
			SAXParserFactory spfactory = SAXParserFactory.newInstance();
			spfactory.setValidating(false);
			
			SAXParser saxParser = spfactory.newSAXParser();
			
			xmlReader = saxParser.getXMLReader();
			xmlReader.setContentHandler(new HandelXML());
			
			InputSource source = new InputSource("TemplateWD.xml");
			xmlReader.parse(source);
			
		} catch( SAXException e) {
		e.printStackTrace();
		System.exit(0);
	} catch (Exception e)
		{
			System.err.println(e);
//			System.exit(1);
			System.exit(0);
		}
  	}
/////////////////////////////////////////////////////////
  	
  	int getNumberFields()
  	{
  		return fieldCount;
  	}
  	
  	FieldDescriptor getField(int index)
  	{
  		return (FieldDescriptor)fields[index];
  	}
  	
  	int getNumberActions()
  	{
   		return operationCount;
  	}
  	
  	OperationDescriptor getAction(int index)
  	{
  		return (OperationDescriptor)operations[index];
  	}
  	
	private Object[] fields = new Object[64];
	private Object[] operations = new Object[64];
	
/////////////////////////////////////////////////////////

}

this code runs correctly as a separated java-program.

I bound it into the Webdynpro-Program by using

// “Create“ backend connection to ApplicationDescriptor.java 
ApplicationDescriptor theDescriptor = new ApplicationDescriptor();

the j2ee Engine was shut down automatically when I ran the Webdynpro-program. There was an exception at the time of loading the xml-file.

The xml-file is in the folder srcpackages..., together with the java-class.

Would someone tell me, what I did wrong? I'm just a beginner in java and I'm still learning it.

Thank you very much in advance.

vivian

[Former Member · Accepted solution]

Vivian,

1. Place your file directly under src/packages directory in your project.

2. Instead of

 
InputSource source = new InputSource("TemplateWD.xml");

use this:

InputSource source = new InputSource
(
  this.getClass.getClassLoader()
    .getResource("TemplateWD.xml")
      .toExternalForm()
);

Valery Silaev

EPAM Systems

http://www.NetWeaverTeam.com

Message was edited by: Valery Silaev

[Former Member · Accepted solution]

Hi Valery, hi Sebastian,

thank you for the answers.

I tried the code from Valery, but the same happened again.

I'm watching it in the debugging. The problem seems to be at the step "ApplicationLoader(ClassLoader).loadClassInternal(String)line:302 [local variables unavailable] "

At "InputSource source = new InputSource..." the Debuggingprocess went into the Exception:

"private synchronized Class loadClassInternal(String name)

throws ClassNotFoundException

{

return loadClass(name);

}

"

(the "name" in it is "local/ZDA_WD2"

"ZDA_WD2" is the name of my project,

btw, j2ee is on the same computer. )

and then I got this

"Source not found for ApplicationLoader(ReferencedLoader).loadClass(String)"

Would you pls. tell me what it means?

thank you very much.

regards

vivian

[Former Member · Accepted solution]

Could you post complete stack trace as it appears in browser window?

VS

[Former Member · Accepted solution]

Thank you!

I hope you meant this part of Stack trace:

Thread [ID#0.0] (Suspended)

ApplicationLoader(ReferencedLoader).loadClass(String) line: 332

ApplicationLoader(ClassLoader).loadClassInternal(String) line: 302 [local variables unavailable]

ApplicationDescriptor.<init>() line: 148

ZDA2.wdDoInit() line: 97

InternalZDA2.wdDoInit() line: 105

DelegatingComponent.doInit() line: 95

DelegatingComponent(Controller).initController() line: 215

DelegatingComponent(Controller).init() line: 200

ClientApplication(ClientComponent).init() line: 346

ClientApplication.init() line: 349

WebDynproMainTask.execute() line: 599

HtmlClient(AbstractClient).executeTasks(ITask) line: 59

ClientManager.doProcessing() line: 251

DispatcherServlet.doWebDynproProcessing(Task, HttpServletRequest, HttpServletResponse) line: 154

DispatcherServlet.doContent(HttpServletRequest, HttpServletResponse) line: 116

DispatcherServlet.doGet(HttpServletRequest, HttpServletResponse) line: 48

DispatcherServlet(HttpServlet).service(HttpServletRequest, HttpServletResponse) line: 740

DispatcherServlet(HttpServlet).service(ServletRequest, ServletResponse) line: 853

HttpHandlerImpl.runServlet(String, HttpParameters, ApplicationContext) line: 391

HttpHandlerImpl.handleRequest(String, HttpParameters) line: 265

RequestAnalizer.startServlet(String) line: 345

RequestAnalizer.startServlet(MessageBytes) line: 323

RequestAnalizer.invokeWebContainer() line: 865

RequestAnalizer.handle() line: 240

Client.handle() line: 92

Processor.request(int, int, byte[], int, int) line: 148

ApplicationSessionMessageListener.process(int, int, byte[], int, int, int) line: 37

UnorderedChannel$MessageRunner.run() line: 71

ActionObject.run() line: 37

AccessController.doPrivileged(PrivilegedAction, AccessControlContext) line: not available [native method]

SingleThread.execute(ThreadContextImpl) line: 94

SingleThread.run() line: 162

I also got this :

Debugger Source Lookup

The source of the type 'com.sap.engine.frame.core.load.ReferencedLoader' could not be shown as the type was not found."

??

vivian

[Former Member · Accepted solution]

Vivian,

Well, it's very strange that project name was used as name of class... Could you post complete code of ApplicationDescriptor <b>constructor</b>

VS

[Former Member · Accepted solution]

In my first post above is the the complete class ApplicationDescriptor.

its constructor again: (details pls see my first post)

 	public ApplicationDescriptor()
  	{
		XMLReader xmlReader = null;
		
		try
		{
			SAXParserFactory spfactory = SAXParserFactory.newInstance();
			spfactory.setValidating(false);
			
			SAXParser saxParser = spfactory.newSAXParser();
			
			xmlReader = saxParser.getXMLReader();
			xmlReader.setContentHandler(new HandelXML());
			
			InputSource source = new InputSource("TemplateWD.xml");
			xmlReader.parse(source);
			
		} catch( SAXException e) {
		e.printStackTrace();
		System.exit(0);
	} catch (Exception e)
		{
			System.err.println(e);
//			System.exit(1);
			System.exit(0);
		}
  	}

I've taken the completete programm from the Webdynpro tutorial 17 "Dynamic UI Generation in WebDynpro" it ran correctly, before I add some code in the class "ApplicationDescriptor" for the upload of the data from xml-file into the arrays

the class "ApplicationDescriptor" is the same as the class "SomeBackEnd.java", except the part for the xml-handling.

here the original coding of the class "SomeBackEnd.java"

public class SomeBackEnd {
  	
  public class FieldDescriptor
  {
  	public FieldDescriptor(String uiType, String name, String type, String label, String tooltip, Object init)
  	{
  		this.uiType = uiType;
  		this.name = name;
  		this.type = type;
  		this.label = label;
  		this.tooltip = tooltip;
  		this.init = init;
  	}
  	
  	String getUIType(){ return uiType; };
  	String getName(){ return name; };
  	String getType(){ return type; };
  	String getLabel(){ return label; };
  	String getTooltip(){ return tooltip; };
  	Object getInit(){return init; };
  	
  	private String uiType;
  	private String name;
  	private String type;
  	private String label;
  	private String tooltip;
  	private Object init;	
  }
  
  public class  OperationDescriptor
  {
  	
  	OperationDescriptor(String name, String displayText, String tooltip)
  	{
  		this.name = name;
  		this.displayText = displayText;
  		this.tooltip = tooltip;	
  	}
  	
  	String getName(){ return name; };
  	String getDisplayText(){ return displayText;  };
  	String getTooltip(){ return tooltip; };
  	
  	private String name;
  	private String displayText;
  	private String tooltip;	
  }
  	
  	int getNumberFields()
  	{
  		return fields.length;
  	}
  	
  	FieldDescriptor getField(int index)
  	{
  		return (FieldDescriptor)fields[index];
  	}
  	
  	int getNumberActions()
  	{
  		return operations.length;
  	}
  	
  	OperationDescriptor getAction(int index)
  	{
  		return (OperationDescriptor)operations[index];
  	}
  	
  	private Object[] fields = {
  		new FieldDescriptor("InputField","firstName","com.sap.dictionary.string","First Name","Enter first name here",""),
  		new FieldDescriptor("InputField","lastName","com.sap.dictionary.string","Last Name","Enter last name here",""),
		new FieldDescriptor("InputField","birthday","com.sap.dictionary.date","Date of Birth","Enter date here", null),
  		new FieldDescriptor("DropDownByKey","country","com.sap.tut.wd.dynamic.simpletype.Country","Country","Choose your country here",""),
  		new FieldDescriptor("RadioButtonGroupByKey","sex","com.sap.tut.wd.dynamic.simpletype.Sex","Sex","Choose your sex here",""),
  		new FieldDescriptor("CheckBox","isManager","com.sap.dictionary.boolean","Is a Manager","Checked if person is a manager", new Boolean(false))  	
  	};
  	
  	private Object[] operations = {
  		new OperationDescriptor ("delete", "Delete", "Delete your input."),
  		new OperationDescriptor ("save", "Save", "Save current record."),
  	};
   		

}

[Former Member · Accepted solution]

Vivian,

Now I'm wondering <b>where you have applied <i>my code</i></b> while I told you to apply it in ApplicationDescriptor constructor (lines to create input source). And you are posting <b>unchanged</b> code...

VS

Message was edited by: Valery Silaev

[Former Member · Accepted solution]

<b>I'm very sorry, that was the code from my first post. Now the code in the program.</b>

  	public ApplicationDescriptor()
  	{
		XMLReader xmlReader = null;
		
		try
		{
			SAXParserFactory spfactory = SAXParserFactory.newInstance();
			spfactory.setValidating(false);
			
			SAXParser saxParser = spfactory.newSAXParser();
			
			xmlReader = saxParser.getXMLReader();
			xmlReader.setContentHandler(new HandelXML());
			

	InputSource source = new InputSource
	(
this.getClass().getClassLoader().getResource("TemplateWD.xml").toExternalForm()

	);
			xmlReader.parse(source);
			
		} catch( SAXException e) {
		e.printStackTrace();
		System.exit(0);
	} catch (Exception e)
		{
			System.err.println(e);
			System.exit(0);
		}
  	}

[Former Member · Accepted solution]

Vivian,

Then,

1. NEVER USE THIS:

try
{
...
} catch (Exception e)
{
  System.err.println(e);
  <b>System.exit(0);</b>
}

Instead do something like this:

try
{
...
} catch (Exception e)
{
  System.err.println(e);
  <b>throw new RuntimeException(ex);</b>
}

Otherwise you are stopping web server.

2. Try to place "TemplateWD.xml" to nested folder, say /src/packages/<b>xslt/TemplateWD.xml</b> -- JDK 1.4 doesn't like "default" package, so probably this causes such magic error. Also replace line with InputSource to

InputSource source = new InputSource
(
  ApplicationDescriptor.class.getClassLoader()
   .getResource("xslt/TemplateWD.xml")
     .toExternalForm()
);

VS

[Former Member · Accepted solution]

Hi,

thank you for the hint about shutting down the Server. Now I don't have to wait for the restart of the server.

I tried different ways to provide the path of the xml-file. it still failed to find it

"at com.sap.fy.zda2.ApplicationDescriptor.<init>(ApplicationDescriptor.java:153)"

I got during debugging the popup "Debugger Source Lookup"

for "The source of the type 'com.sap.engine.frame.core.load.ReferencedLoader' could not be shown as the type was not found."

and then the message

"Source not found for ApplicationLoader(ResourceLoader).getResource(String)line:163"

[Former Member · Accepted solution]

Vivian,

If you may, ZIP your project and send it to me: vsilaev AT gmail DOT com.

VS

[Former Member · Accepted solution]

Hi Valery,

you were right. My NWDS seemed to be in a bad mood. ;). I deleted the complete project and imported it again. Now it works correctly!!

Thank you for your help.

best regards

vivian

[Former Member]

Vivian,

you may check

to load your XML without using classloader

Best regards,

Nick

[Former Member]

Vivian,

please provide some more info. Post the stacktrace of your exception.

regards

Sebastian