Java设计模式——工厂模式

工厂模式是我们常用到的一种设计模式，它是一种创建模式。使用工厂模式的时候，我们不需要公开创建了对象的细节，只需要提供接口即可。

下面以一个例子说明。创建Shape接口以及它的实现类（Circle、Square、Rectangle），通过ShapeFactory类获取需要的实例。

1、创建接口Shape

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public interface Shape {    void draw(); }

2、创建实现类Circle、Square、Rectangle　

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//  Rectangle public class Rectangle implements Shape {      @Override    public void draw() {       System.out.println("Inside Rectangle::draw() method.");    } }   //  Square public class Square implements Shape {      @Override    public void draw() {       System.out.println("Inside Square::draw() method.");    } }   //  Circle public class Circle implements Shape {      @Override    public void draw() {       System.out.println("Inside Circle::draw() method.");    } }

3、创建ShapeFactory类（工厂类）

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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;    } }

4、其他客户端FactoryPatternDemo，通过ShapeFactory，传递正确的参数，得到相应的实例

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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();    } }

5、测试结果

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Inside Circle::draw() method. Inside Rectangle::draw() method. Inside Square::draw() method.