先看下一个简单的实现：
1 package org.masque.designpatterns.factorymethod.one; 2 /** 3 * 4 * Description: Sample子类的标示 5 * BeanEm.java Create on 2014年7月11日 下午2:37:58 6 * @author masque.java@outlook.com 7 * @version 1.0 8 * Copyright (c) 2014 Company,Inc. All Rights Reserved. 9 */10 public enum BeanEm {11 12 ONE,13 14 TWO,15 16 THREE;17 }
package org.masque.designpatterns.factorymethod.one;/** * * Description:抽象父类 * Sample.java Create on 2014年7月11日 下午3:56:01 * @author masque.java@outlook.com * @version 1.0 * Copyright (c) 2014 Company,Inc. All Rights Reserved. */public abstract class Sample { public Sample(){ System.out.println(this); }}
1 package org.masque.designpatterns.factorymethod.one; 2 /** 3 * 4 * Description:子类A 5 * SampleA.java Create on 2014年7月11日 下午3:56:32 6 * @author masque.java@outlook.com 7 * @version 1.0 8 * Copyright (c) 2014 Company,Inc. All Rights Reserved. 9 */10 public class SampleA extends Sample{11 12 public SampleA(){13 }14 } 1 package org.masque.designpatterns.factorymethod.one; 2 /** 3 * 4 * Description:子类B 5 * SampleB.java Create on 2014年7月11日 下午3:56:32 6 * @author masque.java@outlook.com 7 * @version 1.0 8 * Copyright (c) 2014 Company,Inc. All Rights Reserved. 9 */10 public class SampleBextends Sample{11 12 public SampleB(){13 }14 }
1 package org.masque.designpatterns.factorymethod.one; 2 3 /** 4 * 5 * Description: BeanFactory.java Create on 2014年7月11日 下午2:38:29 6 * 7 * @author masque.java@outlook.com 8 * @version 1.0 Copyright (c) 2014 Company,Inc. All Rights Reserved. 9 */10 public class BeanFactory {11 12 public static Sample createSample(BeanEm em) {13 switch (em) {14 case ONE:15 return new SampleA();16 case TWO:17 return new SampleB();18 default:19 return null;20 }21 }22 }
1 package org.masque.designpatterns.factorymethod.one; 2 /** 3 * 4 * Description:测试 5 * Test.java Create on 2014年7月11日 下午3:56:59 6 * @author masque.java@outlook.com 7 * @version 1.0 8 * Copyright (c) 2014 Company,Inc. All Rights Reserved. 9 */10 public class Test {11 12 public static void main(String[] args) {13 BeanFactory.createSample(BeanEm.ONE);14 BeanFactory.createSample(BeanEm.TWO);15 }16 }
先定义一个抽象的父类
1 package org.masque.designpatterns.factorymethod.two; 2 3 /** 4 * 5 * Description: Shape.java Create on 2014年7月10日 下午4:53:27 6 * 7 * @author masque.java@outlook.com 8 * @version 1.0 Copyright (c) 2014 Company,Inc. All Rights Reserved. 9 */10 public abstract class Shape {11 // 勾画shape12 public abstract void draw();13 14 // 擦去 shape15 public abstract void erase();16 17 public String name;18 19 public Shape(String name) {20 this.name = name;21 }22 } 再定义一个抽象工厂的父类
1 package org.masque.designpatterns.factorymethod.two; 2 3 public abstract class ShapeFactory { 4 protected abstract Shape factoryMethod(String aName); 5 6 // 在anOperation中定义Shape的一系列行为 7 public void anOperation(String aName) { 8 Shape s = factoryMethod(aName); 9 System.out.println("The current shape is: " + s.name);10 s.draw();11 s.erase();12 }13 } 子类一：
1 package org.masque.designpatterns.factorymethod.two; 2 /** 3 * 4 * Description: 5 * Circle.java Create on 2014年7月10日 下午5:28:06 6 * @author masque.java@outlook.com 7 * @version 1.0 8 * Copyright (c) 2014 Company,Inc. All Rights Reserved. 9 */10 public class Circle extends Shape {11 12 public void draw() {13 System.out.println("It will draw a circle.");14 }15 16 public void erase() {17 System.out.println("It will erase a circle.");18 }19 20 // 构造函数21 public Circle(String name) {22 super(name);23 }24 25 } 1 package org.masque.designpatterns.factorymethod.two; 2 /** 3 * 4 * Description: 5 * CircleFactory.java Create on 2014年7月10日 下午5:28:18 6 * @author masque.java@outlook.com 7 * @version 1.0 8 * Copyright (c) 2014 Company,Inc. All Rights Reserved. 9 */10 public class CircleFactory extends ShapeFactory {11 // 重载factoryMethod方法,返回Circle对象12 protected Shape factoryMethod(String aName) {13 return new Circle(aName + " (created by CircleFactory)");14 }15 } 子类二：
1 package org.masque.designpatterns.factorymethod.two; 2 /** 3 * 4 * Description: 5 * Square.java Create on 2014年7月10日 下午5:28:25 6 * @author masque.java@outlook.com 7 * @version 1.0 8 * Copyright (c) 2014 Company,Inc. All Rights Reserved. 9 */10 public class Square extends Shape {11 public void draw() {12 System.out.println("It will draw a square.");13 }14 15 public void erase() {16 System.out.println("It will erase a square.");17 }18 19 // 构造函数20 public Square(String name) {21 super(name);22 }23 } 1 package org.masque.designpatterns.factorymethod.two; 2 /** 3 * 4 * Description: 5 * SquareFactory.java Create on 2014年7月10日 下午5:28:31 6 * @author masque.java@outlook.com 7 * @version 1.0 8 * Copyright (c) 2014 Company,Inc. All Rights Reserved. 9 */10 public class SquareFactory extends ShapeFactory {11 12 // 重载factoryMethod方法,返回Square对象13 protected Shape factoryMethod(String aName) {14 return new Square(aName + " (created by SquareFactory)");15 }16 } 测试：
1 package org.masque.designpatterns.factorymethod.two; 2 /** 3 * 4 * Description: 5 * Test.java Create on 2014年7月10日 下午5:28:44 6 * @author masque.java@outlook.com 7 * @version 1.0 8 * Copyright (c) 2014 Company,Inc. All Rights Reserved. 9 */10 public class Test {11 12 public static void main(String[] args) {13 ShapeFactory sf1 = new SquareFactory();14 ShapeFactory sf2 = new CircleFactory();15 sf1.anOperation("Shape one");16 sf2.anOperation("Shape two");17 }18 } The current shape is: Shape one (created by SquareFactory)
It will draw a square.It will erase a square.The current shape is: Shape two (created by CircleFactory)It will draw a circle.It will erase a circle.这样做能够避免修改原有的代码，缺点是:代码量增加了不少！！！