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SUBSCRIBE TO RAM N JAVAImplementing the Front Controller Pattern
In software design, the Front Controller Pattern is a powerful way to manage complex web applications. By providing a single entry point for all requests, you can handle common tasks—like security and logging—in one place instead of repeating code across dozens of different files.
1. The Core Idea
Think of the Front Controller as a Receptionist in a large office building. Instead of guests wandering around trying to find the right room, they all talk to the receptionist first. The receptionist checks their ID (Security) and then directs them to the correct office (Dispatching).
2. Key Best Practices
To implement this pattern effectively, keep these three points in mind:
- Keep it Lightweight: The controller should delegate the "heavy lifting" to other specialized classes.
- Centralize Common Logic: Tasks like user authentication or tracking page views should happen here.
- Use a Dispatcher: The controller should use a separate 'Dispatcher' object to figure out which view or data to return.
3. Why Developers Love It
For beginners, this pattern might seem like extra work at first, but it makes your application much easier to scale. When you need to add a new security feature, you only have to change it in one file rather than fifty!
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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");
}
}
public class SalaryView
{
public void show()
{
System.out.println("Displaying Salary Page");
}
}
public class AccountView
{
public void show()
{
System.out.println("Displaying Account Page");
}
}
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();
}
}
}
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);
}
}
}
See also:
