design pattern

general/DesignPattern.md

@@ -0,0 +1,224 @@
+# Design Pattern
+
+Contents:
+
+- [Types of Design Patterns](#Types of Design Patterns)
+- [Factory Pattern](#Factory Pattern)
+- [Singleton Pattern](#Singleton Pattern)
+- [MVC Pattern](#MVC Pattern)
+
+<a name="Types of Design Patterns"/>
+
+## Types of Design Patterns
++ Creational Patterns
+  - hide creation logic
++ Structural Patterns
+  - class and object composition
++ Behavioral Patterns
+  - communication between objects
++ J2EE Patterns
+
+
+<a name="Factory Pattern"/>
+
+## Factory Pattern
++ create an interface
+
+``` public interface Shape{
+	 void draw();
+    }
+```
+
++ create concrete classes
+
+``` public class Rectangle implements Shape{
+	   @Override
+	   public void draw(){
+	      System.out.println("Inside Rectangle");
+       }
+    }
+```
+
+``` public class Circle implements Shape{
+	   @Override
+	   public void draw(){
+	      System.out.println("Inside Circle");
+       }
+    }
+```
+
++ create factory to generate concrete classes
+
+``` public class ShapeFactory{
+	   public Shape getShape(String type){
+	      if(type == null){
+	         return null;   
+	      }
+	      if(shape.equalsIgnoreCase("Rectangle")){
+             return new Rectangle();
+	      }
+	      if(shape.equalsIgnoreCase("Circle")){
+             return new Circle();
+	      }
+	      return null
+	   }
+    }
+```
+
++ demo
+
+``` public class Demo{
+	   ShapeFactory factory = new ShapeFactory();
+	   Shape circle = factory.getShape("Circle");
+	   circle.draw();
+	   Shape rectangle = factory.getShape("Rectangle");
+	   rectangle.draw();
+    }
+```
+
+<a name="Singleton Pattern"/>
+
+## Singleton Pattern
++ create singleton class
+
+``` public class SingleObject{
+	   private static SingleObject ins = new SingleObject();
+
+	   private SingleObject(){}
+
+	   public static SingleObject getInstance(){
+	   	   return ins;
+	   }
+
+	   public void show(){
+	   	   System.out.println("Hello");
+	   }
+    }
+```
+
++ demo
+
+``` public class Demo{
+	   public static void main(String[] args){
+	       SingleObject obj = SingleObject.getInstance();
+	       obj.show();
+	   }
+    }
+```
+
+<a name="MVC Pattern"/>
+
+## MVC Pattern
++ Model-View-Controller
+  - Model: represent object, can have logic to update controller if its data changes
+  - View: represent visualization of data from Model
+  - Controller: act on Model and View, control data flow into Model and update View when data changes
+
++ Structure
+  - app: models, views, controllers
+  - config: global server configurations
+  - lib: assorted libraries
+
++ Procedure
+  - server routes the request to certain controller
+  - controller interprets the request, load reqested information from models
+  - controller passes information from model to view
+  - final view is sent to user
+
++ Model
+
+``` public class Student{
+       private String id;
+       private String name;
+
+       public String getId(){
+           return id;
+       }
+
+       public String getName(){
+           return name;
+       }
+
+       public void setId(String id){
+           this.id = id;
+       }
+
+       public void setName(String name){
+           this.name = name;
+       }	
+    }
+```
+
++ View
+
+``` public class StudentView{
+	   public void printInfo(String studentName, String studentId){
+	        System.out.println("Student: " + studentName);
+	        System.out.println("Student ID: " + studentId);
+	   }
+    }
+```
+
++ Controller
+
+``` public class StudentController{
+	   private Student model;
+	   private StudentView view;
+
+	   public StudentController(Student model, StudentView view){
+	   	   this.model = model;
+	   	   this.view = view;
+	   }
+
+	   public void setStudentName(String name){
+	   	   model.setName(name);
+	   }
+
+	   public void setStudentId(String id){
+	   	   model.setId(id);
+	   }
+
+	   public String getStudentName(){
+	   	   return model.getName();
+	   }
+
+	   public String getStudentId(){
+	   	   return model.getId();
+	   }
+
+	   public void updateView(){
+	   	   view.printInfo(model.getName(), model.getId());
+	   }
+    }
+```
+
++ Demo
+
+``` public class Demo{
+	  public static void main(String[] args){
+	      Student model = getStudentFromDatabase();
+	      StudentView view = new StudentView();
+	      StudentController controller = new StudentController(model,view);
+
+	      controller.updateView();
+
+	      controller.setStudentName("Other name");
+	      controller.updateView();
+	  }
+    }
+```
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+