Bridge Pattern

2023-12-13 in Design Patterns

Bridge Pattern에 대해 설명하는 페이지입니다.

Environment

• Programming Language: Java

Index

• Index
• Introduction
• Characteristics
• Participants
• How to Use (Example)
• Comments

Introduction

• Purpose
  • Defines an abstraction object structure independently of the implementation object structure in order to limit coupling.
• Use When
  • Abstractions and implementations should not be bound at compile time.
  • Abstractions and implementations should be independently extensible.
  • Implementation details should be hidden from the client.

Characteristics

• Separate the variations in abstraction from the variations in implementation so that the number of classes only grows linearly.
• Decouples an abstraction from its implementation so that the two can vary independently.

Participants

• Abstraction
  • defines the abstraction’s interface
  • maintains a reference to the implementor
  • forwards requests to the implementor (collaboration)
• RefinedAbstraction
  • extends abstraction interface
• Implementor
  • defines interface for implementations
• ConcreteImplementor
  • implements Implementor interface, i.e. defines an implementation

How to Use (Example)

• Abstraction

  public abstract class Shape {
      private Drawing dp;
  
      public Shape(Drawing dp) {
          this.dp = dp;
      }
  
      public abstract void draw();
  
      public void drawLine(double x1, double y1, double x2, double y2) {
          this.dp.drawLine(x1, y1, x2, y2);
      }
  
      public void drawCircle(double x, double y, double r) {
          this.dp.drawCircle(x, y, r);
      }
  }
  

• RefinedAbstraction

  public class Rectangle extends Shape {
      private double x1;
      private double y1;
      private double x2;
      private double y2;
    
      public Rectangle(Drawing dp, double x1, double y1, double x2, double y2) {
          super(dp);
          this.x1 = x1;
          this.y1 = y1;
          this.x2 = x2;
          this.y2 = y2;
      }
  
      @Override
      public void draw() {
          drawLine(x1, y1, x2, y1);
          drawLine(x2, y1, x2, y2);
          drawLine(x2, y2, x1, y2);
          drawLine(x1, y2, x1, y1);
      }
  }
  

  public class Circle extends Shape {
      private double x;
      private double y;
      private double r;
  
      public Circle(Drawing dp, double x, double y, double r) {
          super(dp);
          this.x = x;
          this.y = y;
          this.z = z;
      }
  
      public void draw() {
          drawCircle(x, y, r);
      }
  }
  

• Implementor

  public abstract class Drawing {
      public abstract void drawLine(double x1, double y1, double x2, double y2);
      public abstract void drawCircle(double x, double y, double r);
  }
  

• ConcreteImplementor

  public class V1Drawing extends Drawing {
      public void drawLine(double x1, double y1, double x2, double y2) {
          DP1.draw_a_line(x1, y1, x2, y2);
      }
  
      public void drawCircle(double x, double y, double r) {
          DP1.draw_a_circle(x, y, r);
      }
  }
  

  public class V2Drawing extends Drawing {
      public void drawLine(double x1, double y1, double x2, double y2) {
          DP2.drawLine(x1, y1, x2, y2);
      }
  
      public void drawCircle(double x, double y, double r) {
          DP2.drawCircle(x, y, r);
      }
  }
  

Comments

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