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Archive for June, 2009

Level order traversal - Breadth-first

Here is implementation of level order traversal of a binary tree.

Level order traversal is nothing more than traversing each level at a time

           10              Lev 1
          /   \
        9     15          Lev  2
      /      /   \
    7      12    17      Lev 3

Output

10 9 15 7 12 17

AVL Tree example

++++++++++++++++++++++
69:  29  77
29:  15  48
15:  5  23
5:  3  11
11:  -  14
23:  16  26
16:  -  18
48:  33  64
33:  32  46
64:  50  68
77:  72  84
72:  71  76
84:  80  89
80:  79  82
89:  87  93
++++++++++++++++++++++
The level order result is:
++++++++++++++++++++++
69 29 77 15 48 72 84 5 23 33 64 71 76 80 89 3 11 16 26 32 46 50 68 79 82 87 93 14 18
++++++++++++++++++++++

Implementation

/**
 * Implementation of Level order traversal
 * Prints nodes at each level left to right
 */
template <class Record>
void AVL_tree<Record>::level_order() {
	cout << "++++++++++++++++++++++" << endl;
	if(this->root == NULL){
		cout << "EMPTY TREE" << endl;
	}else{
		cout << endl;
		queue<Binary_node<Record>*> nodeQueu;
		nodeQueu.push(this->root);
		while(!nodeQueu.empty()){
			Binary_node<Record>* entry=nodeQueu.front();
			cout<<entry->data<<" ";
			if(entry->left != NULL){
				nodeQueu.push(entry->left);
			}
			if(entry->right != NULL){
				nodeQueu.push(entry->right);
			}
			nodeQueu.pop();
		}
	}
	cout << "\n++++++++++++++++++++++" << endl;
}

Complexity

Running time complexity of this algorithm is O(n) since every node will have to be explored

Display all managed-beans in JSF at runtime

Sometimes we like to see whats going on under the hood of jsf application (Checkout my JSFConsole). One such task is being able to display all the registered managed-beans during runtime.
Here we can see all registered beans, including implicit object(cookie,header,param etc…)

Result

     a4j
     a4jSkin
     ajaxContext
     ajaxHandler
     application
     applicationScope
     beeHive       --- My Managed bean
     cookie
     facesContext
     header
     headerValues
     initParam
     param
     paramValues
     request
     requestScope
     richSkin
     session
     sessionScope
     view

Source

/**
	 * Retrieve all registered beans for given {@link ScopeType}
	 * @param scopeType to search in
	 * @return List of beanNames
	 */
	public static List<String> getRegisteredBeans(ScopeType scopeType){
		FacesContext facesContext=FacesContext.getCurrentInstance();
		ApplicationAssociate application = ApplicationAssociate.getInstance(facesContext.getExternalContext());
		BeanManager  beanManager = application.getBeanManager();
		Map<String, BeanBuilder> beanMap=beanManager.getRegisteredBeans();
		Set<Entry<String, BeanBuilder>>beanEntries=beanMap.entrySet();
		List<String> registeredBeans=new ArrayList<String>();
		for(Entry<String, BeanBuilder> bean:beanEntries){
			String beanName=bean.getKey();
			if(!beanManager.isManaged(beanName)){
				continue;
			}			
			BeanBuilder builder=bean.getValue();
			Scope bScope=builder.getScope();
			if(scopeType==ScopeType.ALL || bScope.toString().equals(scopeType.toString())){
				registeredBeans.add(beanName+":"+bScope.toString());
			}
		}
 
		if(scopeType==ScopeType.ALL || scopeType==ScopeType.IMPLICIT){
			List<String> implicitList=getProperties(new ImplicitObjectELResolver(), null);
			for(String implicitBeanName:implicitList){
				registeredBeans.add(implicitBeanName+":"+ScopeType.IMPLICIT.toString());
			}
		}
 
		Collections.sort(registeredBeans);
		return registeredBeans;
	}

ScopeType is nothing more than an emun wrapper

 
/**
 * Scope type with additional properties for all/implicit
 * @author devil
 *
 */
public enum ScopeType {
	//Really not a scope but a marker
	ALL("all"),
	IMPLICIT("implicit"),
 
	REQUEST("request"),
	SESSION("session"),
	APPLICATION("application");
 
	String scope;
	ScopeType(String scope) {
		this.scope = scope;
	}
 
	public String toString() {
		return scope;
	}
 
 
	/**
	 * Get Enum from value
	 * @param name
	 * @return
	 */
	public static ScopeType fromValue(String name) {
		name=name!=null?name.toUpperCase():"";
		for(ScopeType v:values()){
			if(v.name().equals(name)){
				return v;
			}
		}
		//By default return all scoped objects
		return ScopeType.ALL;
	}
}

TabWidget demo project

Sorry it took little longer than expected, run in some issues with cupcake (SDK 1.5)
I have attached a Demo project for all interested with  some screenshots and modified .project for TabWidget Project(fixes cupcake problem ref http://groups.google.com/group/android-developers/browse_thread/thread/5537ae10e4143240) if you use eclipse.

1. My env:
Eclipse Version: 3.4.2
Android SDK 1.5
Windows

2.After you import the TabWidgedDemo project you will probably need to fix your buildpath.
Make sure to add TabWidet as a reference to TabWidgedDemo.

3.In TabWidged project you will need to update the .project file otherwise you will get Verify error when deploying to the device.

If you have any questions let me know, I hope you enjoy the project, more improvements to come

Download tabwidgetdemo for eclipse

Remove/Change default constraints sql 2000/2005

Problem

When we add default constraint on a field it is automatically assigned a name in following format

Format:
DF__tablename__PARTOFFIELDNAME__HASHCODE
Example:
DF__scheduled__CREAT__00DF2177
DF__scheduled__MODIF__01D345B0

HashCode part of the format is different on each database so we can’t just find the name of constraint and use that in our alter script. That’s when sysobjects table comes to the rescue.

This will list all the default field values for all tables

SELECT OBJECT_NAME(ID) AS NameofConstraint,
OBJECT_NAME(parent_obj) AS TableName
FROM sysobjects
 WHERE xtype = 'D'

from here we can construct our TSQL script to suit our needs.

Solution

  1. Get default fields of interes t(ConstraintName, TableName)
  2. Drop each constraint
  3. Add new default constraint with a NAME
/**
@Desc: Remove default constraints from a given table, then add new default constraint
2000/2005 compatible
@Author Greg B.
**/
USE [mydb]
GO
 
BEGIN TRANSACTION
GO
 
Declare MyCursor Cursor FOR
 
SELECT OBJECT_NAME(ID) AS NameofConstraint,
OBJECT_NAME(parent_obj) AS TableName
FROM sysobjects
 WHERE xtype = 'D' 
AND (OBJECT_NAME(parent_obj) = 'procedures' AND  OBJECT_NAME(ID) LIKE '%DF__procedure__INHER%')
 
OR 
(
 OBJECT_NAME(parent_obj) = 'subarea'
AND   (OBJECT_NAME(ID) LIKE '%DF__subarea__ABS_INH__%') 
 OR (OBJECT_NAME(ID) LIKE '%DF__subarea__ASSIGNE__%') 
) 
 
 
DECLARE @SQLScript NVARCHAR(300)
 
Declare @NameofConstraint VARCHAR(255) 
Declare @SchemaName VARCHAR(255) 
Declare @TableName VARCHAR(255) 
Declare @ConstraintType VARCHAR(255) 
 
Open MyCursor
Declare @Count int
SELECT @Count = 0 
FETCH NEXT FROM MyCursor INTO @NameofConstraint, @TableName
WHILE @@FETCH_STATUS = 0
BEGIN
	--PINT 'RECORD='+@NameofConstraint +' :: '+@TableName
	SELECT @SQLScript= 'ALTER TABLE '+ @TableName +' DROP CONSTRAINT '+@NameofConstraint
	EXEC sp_executesql @SQLScript
	SELECT @Count=@Count+1
	--Advance to next record
	FETCH NEXT FROM MyCursor INTO @NameofConstraint,@TableName
END
 
Close MyCursor
DEALLOCATE MyCursor
 
IF @Count != 0
BEGIN
print 'Adding alter'
-- Now we add the constrains back again to the tables with standarized names
  ALTER TABLE [dbo].[procedures] ADD CONSTRAINT DF_PROCEDURE_INHERENT_RISK DEFAULT ((1)) FOR [INHERENT_RISK]
  ALTER TABLE [dbo].[subarea] ADD CONSTRAINT DF_SUBAREA_ABS_INHERENT_RISK DEFAULT ((1)) FOR [ABS_INHERENT_RISK]
  ALTER TABLE [dbo].[subarea] ADD CONSTRAINT DF_SUBAREA_ASSIGNED_INHERENT_RISK DEFAULT ((1)) FOR [ASSIGNED_INHERENT_RISK]
END
 
COMMIT TRANSACTION 
 
IF @@TRANCOUNT > 0
BEGIN
    ROLLBACK TRAN
END 
GO

Serving resources using Resource PhaseListener

PhaseListener designed to serve resources like css, javascript, images, pdf etc.. from jar file

ResourcePhaseListener.java

All required files can be downloaded here.

package com.gregbugaj.jsfdump.console;
 
import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Map;
 
import javax.activation.MimetypesFileTypeMap;
import javax.faces.context.FacesContext;
import javax.faces.event.PhaseEvent;
import javax.faces.event.PhaseId;
import javax.faces.event.PhaseListener;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
 
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
 
import com.gregbugaj.jsfdump.util.JarUtil;
import com.gregbugaj.jsfdump.util.XMLUtil;
/**
 * Serve resources from jar file  back to the user by specifying resource name in resource-config.xml
 * 
 * This works with following syntax if faces servlet is *.jsf  /jsfdump/resource/script.js.jsf
 * or  /jsfdump/resource/script.js if faces servlet is *.*
 * 
 * @author devil
 *
 */
@SuppressWarnings("serial")
public class ResourcePhaseListener implements PhaseListener {
	//This is how the resource will be accessed ex /jsfdump/resource/script.js
	private static final String RESOURCE_PREFIX = "/jsfdump/resource/";
	//Location of where the js, img, css etc files reside inside the jar, we could also placed them in META-INF folder
	private static final String RESOURCE_PATH = "/com/gregbugaj/jsfdump/resources/";
 
	private static Map<String, String> resources=new HashMap<String,String>();
	private boolean isLoaded;
 
	@Override
	public void afterPhase(PhaseEvent event) {
		FacesContext facesContext=event.getFacesContext();
		String rootId=facesContext.getViewRoot().getViewId();
		//Clean up key
		String key=rootId.replace(RESOURCE_PREFIX, "");
		key=key.replace(".xhtml", "");
		key=key.replace(".jsf", "");
		if(!rootId.startsWith(RESOURCE_PREFIX)){
			return; 
		}
 
		//Lazy loading
		if(!isLoaded){
			isLoaded=initResources();
		}	
		String resourceName=resources.get(key);
		//Location of resources inside the jar file
		String fileName=RESOURCE_PATH+resourceName;
		InputStream resourceStream=JarUtil.getStreamFromJar(fileName);
		HttpServletResponse response = (HttpServletResponse) facesContext.getExternalContext().getResponse();
		response.setCharacterEncoding("UTF-8");
		ServletOutputStream sos = null;
		try {
			sos = response.getOutputStream();
			if(resourceStream!=null){
				response.setStatus(HttpServletResponse.SC_OK);
				//Resolve mime type, required that we have activation.jar loaded
				//Additional mime types can be defined in /META-INF/mimes.types  {@link http://java.sun.com/j2ee/sdk_1.3/techdocs/api/javax/activation/MimetypesFileTypeMap.html }
				String contentType = new MimetypesFileTypeMap().getContentType(fileName);
				response.setContentType(contentType);
				byte[] buffer= new byte[1024];
				for (int bytesRead = 0; (bytesRead = resourceStream.read(buffer, 0, buffer.length)) > 0;)
				{
					sos.write(buffer, 0, bytesRead);
				}
			}else{
				//Resource not found
				response.setStatus(HttpServletResponse.SC_NOT_FOUND);
				response.setContentType("text/html");
			}
			sos.flush();
			sos.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
		facesContext.responseComplete();
	}
 
	@Override
	public void beforePhase(PhaseEvent event) {
		//Do nothing
	}
 
	/**
	 * Load resource mapping from resource-config.xml
	 * @return true if we successfully loded resource
	 */
	private boolean initResources() {
		boolean retVal=true;
		InputStream stream=null;	
		try {
			stream=JarUtil.getStreamFromJar("/META-INF/resource-config.xml");
			Document document=XMLUtil.getXmlDocument(stream);
			NodeList resourceNodes=XMLUtil.extract("/resources/resource", document);
			for(int i=0;i<resourceNodes.getLength();i++){
				Node node=resourceNodes.item(i);
				String name=XMLUtil.attributeText(node, "name");
				String src=XMLUtil.attributeText(node, "src");
				//No forward slash in the resource name
				//ex js/scriptname.js not /js/script.js
				if(src.startsWith("/")){
					src=src.replaceFirst("/", "");
				}
				resources.put(name, src);
			}
		}  catch (IOException e) {
			retVal=false;
			e.printStackTrace();
		}
		catch (Exception e) {
			retVal=false;
			e.printStackTrace();
		}
		return retVal;
	}
 
	@Override
	public PhaseId getPhaseId() {
		return PhaseId.RESTORE_VIEW;
	}
}

resource-config.xml

This is where we define resources that we will be serving. One reasons we use xml configuration is to prevent security breaches.

  <?xml version="1.0" encoding="UTF-8"?>
  <resources>
	<resource name="proto.js" src="js/proto.js" />
	<resource name="logo.png" src="images/a.png" />
	<resource name="main.css" src="css/hello.css" />
  </resources>

Two common ways to access the resources are
If faces servlet is *.jsf /jsfdump/resource/script.js.jsf
Of /jsfdump/resource/script.js if faces servlet is *.*

META-INF/mime.types

This is where we add additional mime types, requires that we have activation.jar loaded More info

This file is not required but it helps, for example png files resolve to application/octet-stream rather than image/x-png

Examples

Sidebar3 : Please add some widgets here.