JAVA EE: August 2013

Friday, 30 August 2013

Iterator Design Pattern - Implementation

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Iterator Design Pattern - Implementation

IteratorPatternDemo.Java

import java.util.ArrayList;

import java.util.HashSet;

import java.util.Iterator;

import java.util.Set;

public class IteratorPatternDemo

{

public static void main( String[] args )

{

ArrayList<String> listOfCountries = new ArrayList<String>();

listOfCountries.add("India");

listOfCountries.add("US");

listOfCountries.add("Japan");

listOfCountries.add("France");

Iterator<String> iterator = listOfCountries.iterator();

System.out.println("Iterator type for the Datastructure ArrayList : "+iterator.toString());

System.out.println();

while( iterator.hasNext() )

{

String countryName = iterator.next();

System.out.println("Country Name : " + countryName);

}

System.out.println();

Set<String> setOfCountries = new HashSet<String>();

setOfCountries.add("India");

setOfCountries.add("US");

setOfCountries.add("Japan");

setOfCountries.add("France");

Iterator<String> iterator1 = setOfCountries.iterator();

System.out.println("Iterator type for the Datastructure HashSet : "+iterator1.toString());

System.out.println();

while( iterator1.hasNext() )

{

String countryName = iterator1.next();

System.out.println("Country Name : " + countryName);

}

Output

Iterator type for the Datastructure ArrayList : java.util.AbstractList$Itr@12dacd1

Country Name : India

Country Name : US

Country Name : Japan

Country Name : France

Iterator type for the Datastructure HashSet : java.util.HashMap$KeyIterator@30c221

Country Name : France

Country Name : US

Country Name : Japan

Country Name : India

See also:

Iterator Design Pattern - Introduction

Iterator Design Pattern - KeyPoints

All Design Patterns Links

Iterator Design Pattern - Introduction

Click here to watch in Youtube : https://www.youtube.com/watch?v=Pganyj1dVVU

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Iterator Design Pattern - Introduction

Iterator Design Pattern - KeyPoints

All Design Patterns Links

Intercepting Filter Design Pattern - Implementation

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Intercepting Filter Design Pattern - Implementation

Filter.Java

public interface Filter

{

public void processRequest(String request);

}

AuthenticationFilter.java

public class AuthenticationFilter implements Filter

{

@Override

public void processRequest( String request )

{

System.out.println("Authenticating the request by AuthenticationFilter : " + request);

}

LoggingFilter.java

public class LoggingFilter implements Filter

{

@Override

public void processRequest( String request )

{

System.out.println("Request Tracking is done by LoggingFilter : " + request);

}

Target.java

public class Target

{

public void processRequest( String request )

{

System.out.println("Process the Request by Target Class: " + request);

}

FilterChain.java

import java.util.ArrayList;

import java.util.List;

public class FilterChain

{

private List<Filter> filters = new ArrayList<Filter>();

private Target target;

public void addFilter( Filter filter )

{

filters.add(filter);

}

public void execute( String request )

{

for( Filter filter : filters )

{

filter.processRequest(request);

}

target.processRequest(request);

}

public void setTarget( Target target )

{

this.target = target;

}

FilterManager.java

public class FilterManager

{

FilterChain filterChain;

public FilterManager( Target target )

{

filterChain = new FilterChain();

filterChain.setTarget(target);

}

public void setFilter( Filter filter )

{

filterChain.addFilter(filter);

}

public void filterRequest( String request )

{

filterChain.execute(request);

}

Client.java

public class Client

{

FilterManager filterManager;

public void setFilterManager( FilterManager filterManager )

{

this.filterManager = filterManager;

}

public void sendRequest( String request )

{

filterManager.filterRequest(request);

}

public static void main( String[] args )

{

FilterManager filterManager = new FilterManager(new Target());

filterManager.setFilter(new AuthenticationFilter());

filterManager.setFilter(new LoggingFilter());

Client client = new Client();

client.setFilterManager(filterManager);

client.sendRequest("HOME");

}

Output

Authenticating the request by AuthenticationFilter : HOME

Request Tracking is done by LoggingFilter : HOME

Process the Request by Target Class: HOME

See also:

Intercepting Filter Design Pattern - Introduction

Intercepting Filter Design Pattern - Class and Sequence Diagram

Intercepting Filter Design Pattern - KeyPoints

All Design Patterns Links

Intercepting Filter Design Pattern - Class and Sequence Diagram

Click here to watch in Youtube : https://www.youtube.com/watch?v=5MppAW_lGnQ

Click the below Image to Enlarge

Intercepting Filter Design Pattern - Class and Sequence Diagram

Intercepting Filter Design Pattern - Implementation

Intercepting Filter Design Pattern - KeyPoints

All Design Patterns Links

Intercepting Filter Design Pattern - Introduction

Click here to watch in Youtube : https://www.youtube.com/watch?v=XuIa6NsQAuA

Click the below Image to Enlarge

Intercepting Filter Design Pattern - Introduction

Intercepting Filter Design Pattern - Implementation

Intercepting Filter Design Pattern - KeyPoints

All Design Patterns Links

Front Controller Design Pattern - Implementation

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Front Controller Design Pattern - Implementation - Class Diagram

UserView.java

public class UserView
{
public void show()
{
System.out.println("Displaying User Page");
}
}

SalaryView.java

public class SalaryView
{
public void show()
{
System.out.println("Displaying Salary Page");
}
}

AccountView.java

public class AccountView
{
public void show()
{
System.out.println("Displaying Account Page");
}
}

Dispatcher.java

public class Dispatcher
{
private SalaryView salaryView;
private UserView userView;
private AccountView accountView;

public Dispatcher()
{
salaryView = new SalaryView();
userView = new UserView();
accountView = new AccountView();
}

public void dispatch( String request )
{
if( request.equalsIgnoreCase("USER") )
{
userView.show();
}
else if( request.equalsIgnoreCase("ACCOUNT") )
{
accountView.show();
}
else
{
salaryView.show();
}
}
}

FrontController.java

public class FrontController
{
private Dispatcher dispatcher;

public FrontController()
{
dispatcher = new Dispatcher();
}

private boolean isAuthenticUser()
{
//here you have to write Authentication logic
System.out.println("User is authenticated successfully.");
return true;
}

private void trackRequest( String request )
{
System.out.println("Page requested: " + request);
}

public void dispatchRequest( String request )
{
// log each request
trackRequest(request);
// authenticate the user
if( isAuthenticUser() )
{
dispatcher.dispatch(request);
}
}
}

FrontControllerPatternDemo.java

public class FrontControllerPatternDemo

{

public static void main( String[] args )

{

FrontController frontController = new FrontController();

frontController.dispatchRequest("USER");

System.out.println();

frontController.dispatchRequest("ACCOUNT");

System.out.println();

frontController.dispatchRequest("SALARY");

}