设计模式之简单工厂

2018-08-01 本文已影响9人 tanoak

模拟场景
客户提出要购买100t苹果，然后农场主跑去收购100t苹果给客户

package com.tanoak.create.factory.simple.demo;

/**
 * @author tanoak@qq.com
 * @date 2018/8/1 22:31
 * @Desc
 */
public class Apple {
  private String name ;

  public String getName() {
      return name;
  }

  public void setName(String name) {
      this.name = name;
  }

  public Apple(String name) {
      this.name = name;
  }

  @Override
  public String toString() {
      return "Apple{" +
              "name='" + name + '\'' +
              '}';
  }

  public static void main(String[] args) {
      Apple a = new Apple("红色的苹果") ;
      System.out.println(a.toString());
  }
}

后面客户又想要100t香蕉，于是代码变成

package com.tanoak.create.factory.simple.demo;

/**
 * @author tanoak@qq.com
 * @Desc
 */
public class Banana  {
  private String name ;

  public String getName() {
      return name;
  }

  public void setName(String name) {
      this.name = name;
  }

  public Banana(String name) {
      this.name = name;
  }

  @Override
  public String toString() {
      return "Banana{" +
              "name='" + name + '\'' +
              '}';
  }
  public static void main(String[] args) {
      Apple a = new Apple("红色的苹果") ;
      Banana b = new Banana("香蕉") ;
      System.out.println(a.toString());
  }

}

这样会带来的问题很明显，main方法变得很臃肿，来看下简单工厂是如何解决这个问题的

创建水果接口

package com.tanoak.create.factory.simple;

/** 
 * @author tanoak@qq.com 
 * @Desc
 */ 
public interface IFruit {

  void name();
}

创建工厂类并实现水果接口

package com.tanoak.create.factory.simple;

/**
 * @author tanoak@qq.com
 * @Desc
 */
public class FruitFactory {

   private FruitFactory(){}

   public static IFruit createProduct(String name){//生产水果
       String apple = "apple" ;
       String banana = "banana" ;
       if (name == null) {
           return null;
       }
       if (name.equals(banana)) {
           return new Banana();
       }else if (name.equals(apple)) {
           return new Apple();
       }else {
           return null;
       }
   }
}

苹果与香蕉类实现水果接口

package com.tanoak.create.factory.simple;

/** 
 * @author tanoak@qq.com
 * @date 2018/7/19 16:43
 * @Desc
 */ 
public class Apple implements IFruit{
    private String name ;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Apple(String name) {
        this.name = name;
    }

    public Apple() {
        this.name = name;
    }

    @Override
    public String toString() {
        return "Apple{" +
                "name='" + name + '\'' +
                '}';
    }

    @Override
    public void name() {
        this.setName(name);
        System.out.println("The is Apple");
    }
}
//

package com.tanoak.create.factory.simple;

/** 
 * @author tanoak@qq.com
 * @date 2018/7/19 16:43
 * @Desc
 */ public class Banana implements IFruit{

    private String name ;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Banana(String name) {
        this.name = name;
    }
    public Banana() {
        this.name = name;
    }

    @Override
    public String toString() {
        return "Banana{" +
                "name='" + name + '\'' +
                '}';
    }

    @Override
    public void name() {
        this.setName(name);
        System.out.println("This is Banana");
    }
}

编写好之后，来看Main方法，当需要苹果时只需要修改一个参数就行了，并不需要在main方法中new，有小伙伴可能要问了，这代码没变少反而多了，关于这个问题请看设计模式序言

package com.tanoak.create.factory.simple;
/**
 * @author tanoak@qq.com
 * @Desc  简单工厂模式
 */
public class Main {

    public static void main(String[] args) {
        IFruit apple = FruitFactory.createProduct("apple");//banana
        apple.name();
    }
}

如理解有误，请指正，谢谢

设计模式之简单工厂

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