设计模式之简单工厂

• 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

  1. 创建水果接口

  package com.tanoak.create.factory.simple;
  
  /** 
   * @author tanoak@qq.com 
   * @Desc
   */ 
  public interface IFruit {
  
    void name();
  }
  
  

  2. 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;
            }
        }
     }
     

     3. 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