Java設計模式編程中簡單工廠與抽象工廠模式的使用實例

簡單工廠模式
類圖

通過一個工廠類，以一個條件來創建對應的對象

//業務功能public interface ICalculation { double getResult(double numA, double numB); } public class CalcAdd implements ICalculation { @Override public double getResult(double numA, double numB) { System.out.println("加法"); return numA + numB; } } public class CalcSubtract implements ICalculation { @Override public double getResult(double numA, double numB) { System.out.println("減法"); return numA - numB; } } /* * 簡單工廠模式關注：對象的創建* 建立一個工廠類，對實現了同一接口的或者是存在繼承關係的一些類進行實例的創建*/ public class Test4Simple { public static void main(String[] args) { // String operation = "/"; String operation = "+"; // String operation = "-"; // String operation = "*"; double numA = 182, numB = 33; ICalculation createCalc = CalcSimpleFactory.createCalc(operation); double result = createCalc.getResult(numA, numB); System.out.println(result); } }

簡單工廠的缺陷： 簡單工廠創建產品時需要傳遞相應的參數，如果傳遞不正確就取不到對象了。
改進：多方法創建不同產品類圖

public class CalcMultipleFactory { public static ICalculation produceAdd() { return new CalcAdd(); } public static ICalculation produceSubtract() { return new CalcSubtract(); } public static ICalculation produceMultiply() { return new CalcMultiply(); } public static ICalculation produceDivide() { return new CalcDivide(); } } public class Test4Multiple { public static void main(String[] args) { double numA = 182, numB = 33; ICalculation createCalc = CalcMultipleFactory.produceAdd(); double result = createCalc.getResult(numA, numB); System.out.println(result); createCalc = CalcMultipleFactory.produceSubtract(); result = createCalc.getResult(numA, numB); System.out.println(result); createCalc = CalcMultipleFactory.produceMultiply(); result = createCalc.getResult(numA, numB); System.out.println(result); createCalc = CalcMultipleFactory.produceDivide(); result = createCalc.getResult(numA, numB); System.out.println(result); } }

抽象工廠模式
裡面有幾個概念：抽象工廠、實體工廠、抽象產品、實體產品抽象工廠：定義創建產品的抽象方法實體工廠：具體的創建哪種產品抽象產品：一個接口或基類實體產品：實現具體功能，或派生類圖

//抽象產品1 public interface IProduct1 { public void show(); } //抽象產品2 public interface IProduct2 { public void show(); } //實體產品1 public class Product1 implements IProduct1 { public void show() { System.out.println("創建了1型產品"); } } //實體產品2 public class Product2 implements IProduct2 { public void show() { System.out.println("創建了2型產品"); } } /* * 1A 1B屬於Product1 同一產品等級結構中* 2A 2B屬於Product2 */ public class GradeProduct1A extends Product1 { @Override public void show() { super.show(); System.out.println("這是產品1下的:產品A"); } } public class GradeProduct1B extends Product1 { @Override public void show() { super.show(); System.out.println("這是產品1下的:產品B"); } } public class GradeProduct2A extends Product2 { @Override public void show() { super.show(); System.out.println("這是產品2下的:產品A"); } } public class GradeProduct2B extends Product2 { @Override public void show() { super.show(); System.out.println("這是產品2下的:產品B"); } } //抽象工廠創建不同的抽象產品public interface IFactory { public IProduct1 createProduct1A();//1類產品型號A public IProduct1 createProduct1B();//1類產品型號B public IProduct2 createProduct2A();//2類產品型號A public IProduct2 createProduct2B();//2類產品型號B } //實體工廠創建實體產品，返回類型為抽象產品public class Factory implements IFactory { public IProduct1 createProduct1A() { return new GradeProduct1A(); } public IProduct1 createProduct1B() { return new GradeProduct1B(); } public IProduct2 createProduct2A() { return new GradeProduct2A(); } public IProduct2 createProduct2B() { return new GradeProduct2B(); } } /* * 抽象工廠模式：用來創建一組相關或者相互依賴的對象* * 流程：抽象工廠，實體工廠生產產品* 抽象產品，實體產品實現產品功能* 缺點：當需要增加一個產品(由抽象和實體構成)，工廠都需要更改*/ public class Test4Abstract { public static void main(String[] args) { IFactory factory = new Factory(); IProduct1 product1a = factory.createProduct1A(); product1a.show(); IProduct1 product1b = factory.createProduct1B(); product1b.show(); IProduct2 product2a = factory.createProduct2A(); product2a.show(); IProduct2 product2b = factory.createProduct2B(); product2b.show(); } }