工厂模式是Java中最常用的设计模式之一.这种类型的设计模式属于创建模式,因为此模式提供了创建对象的最佳方法之一.
在Factory模式中,我们创建对象而不将创建逻辑暴露给客户端使用通用接口引用新创建的对象.
我们将创建一个 Shape 接口,实现 Shape 接口的具体类.工厂类 ShapeFactory 被定义为下一步.
FactoryPatternDemo ,我们的演示类将使用 ShapeFactory 获取 Shape 对象.它会将信息( CIRCLE/RECTANGLE/SQUARE )传递给 ShapeFactory 以获取所需的对象类型.
创建一个界面.
Shape.java
public interface Shape { void draw(); }
创建实现相同界面的具体类.
Rectangle.java
public class Rectangle implements Shape { @Override public void draw() { System.out.println("Inside Rectangle::draw() method."); } }
Square.java
public class Square implements Shape { @Override public void draw() { System.out.println("Inside Square::draw() method."); } }
Circle.java
public class Circle implements Shape { @Override public void draw() { System.out.println("Inside Circle::draw() method."); } }
创建工厂以生成具体类的对象基于给定的信息.
ShapeFactory.java
public class ShapeFactory { //use getShape method to get object of type shape public Shape getShape(String shapeType){ if(shapeType == null){ return null; } if(shapeType.equalsIgnoreCase("CIRCLE")){ return new Circle(); } else if(shapeType.equalsIgnoreCase("RECTANGLE")){ return new Rectangle(); } else if(shapeType.equalsIgnoreCase("SQUARE")){ return new Square(); } return null; } }
使用Factory获取具体类的对象通过传递类型等信息.
FactoryPatternDemo.java
public class FactoryPatternDemo { public static void main(String[] args) { ShapeFactory shapeFactory = new ShapeFactory(); //get an object of Circle and call its draw method. Shape shape1 = shapeFactory.getShape("CIRCLE"); //call draw method of Circle shape1.draw(); //get an object of Rectangle and call its draw method. Shape shape2 = shapeFactory.getShape("RECTANGLE"); //call draw method of Rectangle shape2.draw(); //get an object of Square and call its draw method. Shape shape3 = shapeFactory.getShape("SQUARE"); //call draw method of square shape3.draw(); } }
验证输出.
Inside Circle::draw() method. Inside Rectangle::draw() method. Inside Square::draw() method.