In C#, an application controller is a design pattern used to centralize the flow of an application and manage its various components. It acts as an intermediary between the user interface, business logic, and data access layers.
The application controller pattern helps decouple the different parts of an application, making it easier to maintain and modify. It promotes separation of concerns by keeping the UI code free from business logic and data access code.
In C#, these are the steps to implement the application Controller pattern:
Step 1: Identify the components of the application
For this example, let’s assume we have a task management application with a user interface and business logic components.
Step 2: Define interfaces
Start by defining the interfaces for the user interface and business logic components.
// IUserInterface interface
public interface IUserInterface
{
void DisplayTasks(List<string> tasks);
string GetTaskInput();
void DisplaySuccessMessage(string message);
bool ShouldContinue();
void Shutdown();
}
// IBusinessLogic interface
public interface IBusinessLogic
{
List<string> GetTasks();
void AddTask(string task);
}
Step 3: Implement the interfaces
for the user interface and business logic components.
// ConsoleUserInterface implementation
public class ConsoleUserInterface : IUserInterface
{
public void DisplayTasks(List
{
Console.WriteLine("Tasks:");
foreach (var task in tasks)
{
Console.WriteLine(task);
}
}
public string GetTaskInput()
{
Console.Write("Enter a task: ");
string task = Console.ReadLine();
return task;
}
public void DisplaySuccessMessage(string message)
{
Console.WriteLine(message);
}
public bool ShouldContinue()
{
Console.Write("Do you want to continue? (y/n): ");
string input = Console.ReadLine();
return (input.ToLower() == "y");
}
public void Shutdown()
{
Console.WriteLine("Goodbye!");
}
}
// TaskManagementBusinessLogic implementation
public class TaskManagementBusinessLogic : IBusinessLogic
{
private List<string> _tasks;
public TaskManagementBusinessLogic()
{
_tasks = new List<string>();
}
public List<string> GetTasks()
{
return _tasks;
}
public void AddTask(string task)
{
_tasks.Add(task);
}
}
Step 4: Create the application controller class
Create the application controller class that will manage the flow of the task management application.
// ApplicationController class
public class ApplicationController
{
private readonly IUserInterface _userInterface;
private readonly IBusinessLogic _businessLogic;
public ApplicationController(IUserInterface userInterface, IBusinessLogic businessLogic)
{
_userInterface = userInterface;
_businessLogic = businessLogic;
}
public void Run()
{
bool isRunning = true;
while (isRunning)
{
List<string> tasks = _businessLogic.GetTasks();
_userInterface.DisplayTasks(tasks);
string newTask = _userInterface.GetTaskInput();
_businessLogic.AddTask(newTask);
_userInterface.DisplaySuccessMessage("Task added successfully!");
isRunning = _userInterface.ShouldContinue();
}
_userInterface.Shutdown();
}
}
Step 5: Instantiate the application controller
In the application’s entry point (e.g., Main method), create instances of the user interface and business logic implementations, and then instantiate the application controller.
class Program
{
static void Main(string[] args)
{
IUserInterface userInterface = new ConsoleUserInterface();
IBusinessLogic businessLogic = new TaskManagementBusinessLogic();
ApplicationController appController = new ApplicationController(userInterface, businessLogic);
appController.Run();
}
}
Conclusion: The controller manages the flow of the application, interacting with the user interface and business logic components to display tasks, add new tasks, and provide feedback to the user.
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