[设计模式]简单工厂模式

来源：互联网发布：淘宝怎么搜发票编辑：程序博客网时间：2024/06/05 19:27

抽象工厂模式（abstract factory）

以简单的算术运算为例：

// 运算类public abstract class Operation {public abstract int getResult(int numA, int numB);}

// 加法运算类public class OperationAdd extends Operation{@Overridepublic int getResult(int numA, int numB) {return numA + numB;}}// 减法运算类public class OperationSub extends Operation{@Overridepublic int getResult(int numA, int numB) {return numA - numB;}}// 乘法运算类public class OperationMul extends Operation{@Overridepublic int getResult(int numA, int numB) {return numA * numB;}}// 除法运算类public class OperationDiv extends Operation{<span style="white-space:pre"></span>@Override<span style="white-space:pre"></span>public int getResult(int numA, int numB) {<span style="white-space:pre"></span>if (numB == 0)<span style="white-space:pre"></span>throw new ArithmeticException("/ by zero");<span style="white-space:pre"></span>return numA / numB;<span style="white-space:pre"></span>}}

// 运算工厂类public class OperationFactory {public static Operation createOperate(String operate) {Operation operation = null;switch (operate) {case "+":operation = new OperationAdd();break;case "-":operation = new OperationSub();break;case "*":operation = new OperationMul();break;case "/":operation = new OperationDiv();break;default:break;}return operation;}}

// 测试类public class Test {public static void main(String[] args) {Operation add = OperationFactory.createOperate("+");System.out.println("1 + 2 = " + add.getResult(1, 2));Operation sub = OperationFactory.createOperate("-");System.out.println("1 - 2 = " + sub.getResult(1, 2));Operation mul = OperationFactory.createOperate("*");System.out.println("1 * 2 = " + mul.getResult(1, 2));Operation div = OperationFactory.createOperate("/");System.out.println("1 / 2 = " + div.getResult(1, 2));}}

添加新的运算类时，只需要增加新的运算类以及修改运算工场类即可，不需要其他与之不相关的类，可以减少错误的修改，避免发生巨大的损失；

修改某个运算类时，直接修改运算类即可，不需要修改工厂类以及其他类，有效的降低了耦合度

0 0