設計模式之簡單工廠模式

工廠模式專門負責將大量有共同接口的類實例化。工廠模式可以動態決定將哪一個類實例化，

不必事先知道每次要實例化哪一個類。

簡單工廠(Simple Factory)模式，又稱靜態工廠方法模式（Static Factory Method Pattern）,是

不同的工廠方法模式的一個特殊表現

 

一個農場，專門生產水果， 在這個系統中需要描述以下水果

葡萄->Grape

草莓->Strawberry

蘋果->Apple

 

建產一個各種水果都適用的接口，各種水果實現這個接口

 

Fruit.java

 

package com.archie.pattern.simplefactory; /** * 所有水果必須實現的接口 * @author archie2010 * */ public interface Fruit { /** * 生長 */ void grow(); /** * 收穫 */ void harvest(); /** * 種植 */ void plant(); }

 

Grape.java

 

package com.archie.pattern.simplefactory; public class Grape implements Fruit{ private boolean seedless;//有無籽 @Override public void grow() { log("Grape is growing.."); } @Override public void harvest() { log("Grape has been harvested"); } @Override public void plant() { log("Grape has been planted."); } public static void log(String msg){ System.out.println(msg); } public boolean isSeedless() { return seedless; } public void setSeedless(boolean seedless) { this.seedless = seedless; } }

 

Strawberry.java

 

package com.archie.pattern.simplefactory; public class Strawberry implements Fruit { public void grow() { log("Strawberry is growing..."); } public void harvest() { log("Strawberry has been harvested."); } public void plant() { log("Strawberry has been planted."); } public static void log(String msg){ System.out.println(msg); } }

 

Apple.java

package com.archie.pattern.simplefactory; public class Apple implements Fruit{ private int treeAge;//樹齡 @Override public void grow() { log("Apple is growing..."); } @Override public void harvest() { log("Apple has been harvested."); } @Override public void plant() { log("Apple has been planted."); } /** * 輔助方法 * @param msg */ public static void log(String msg){ System.out.println(msg); } public int getTreeAge() { return treeAge; } public void setTreeAge(int treeAge) { this.treeAge = treeAge; } }

 

FruitGardener.java

 

package com.archie.pattern.simplefactory; /** * 園丁類，根據客戶端的要求，創建不同的水果對象 * 接到不合法的要示，會拋出BadFruitException * @author archie2010 * */ public class FruitGardener { public static Fruit factory(String which) throws BadFruitException{ if(which.equalsIgnoreCase("apple")){ return new Apple(); }else if(which.equalsIgnoreCase("strawberry")){ return new Strawberry(); }else if(which.equalsIgnoreCase("grape")){ return new Grape(); }else{ throw new BadFruitException("Bad fruit request"); } } }

 

BadFruitException.java

 

package com.archie.pattern.simplefactory; @SuppressWarnings("serial") public class BadFruitException extends Exception{ public BadFruitException(String msg){ super(msg); } }

 

 

Main.java(測試)

 

package com.archie.pattern.simplefactory; public class Main { /** * @param args * @throws BadFruitException */ @SuppressWarnings("static-access") public static void main(String[] args) { FruitGardener gardener=new FruitGardener(); Fruit fruit; try { fruit = gardener.factory("apple"); fruit.plant(); fruit.grow(); fruit.harvest(); } catch (BadFruitException e) { e.printStackTrace(); } } }

 

Console:

 

Apple has been planted.
Apple is growing...
Apple has been harvested.