《大话设计模式》阅读笔记和总结。原书是C#编写的,本人用Java实现了一遍,包括每种设计模式的UML图实现和示例代码实现。
目录:设计模式
Github地址:DesignPattern
定义:通过一个单独的类来做创造实例的过程,这就是工厂
例子:用程序实现输入两个数和运算符号,得到结果。
分析:这个题目并不难,需要考虑的是需要通过面向对象编程来简化代码,降低耦合度,同时又便于修改和复用。因此这里我们用简单工程模式来实现这个功能。
UML图:
代码:
运算类
public abstract class Operation {
private double numberA;
private double numberB;
public double getNumberA() {
return numberA;
}
public void setNumberA(double numberA) {
this.numberA = numberA;
}
public double getNumberB() {
return numberB;
}
public void setNumberB(double numberB) {
this.numberB = numberB;
}
public abstract double getResult();
}
加法类,继承运算类
public class OperationAdd extends Operation {
@Override
public double getResult() {
double result = getNumberA() + getNumberB();
return result;
}
}
减法类,继承运算类
public class OperationSub extends Operation {
@Override
public double getResult() {
double result = getNumberA() - getNumberB();
return result;
}
}
乘法类,继承运算类
public class OperationMul extends Operation {
@Override
public double getResult() {
double result = getNumberA() * getNumberB();
return result;
}
}
除法类,继承运算类
public class OperationDiv extends Operation {
@Override
public double getResult(){
double result = 0;
try {
if (getNumberB() == 0){
throw new Exception("除数不能为0");
}else {
result = getNumberA() / getNumberB();
}
} catch (Exception e) {
e.printStackTrace();
}
return result;
}
}
简单运算工厂类
public class OperationFactory {
public static Operation createOperation(String operate){
Operation oper = null;
switch (operate){
case "+":
oper = new OperationAdd();
break;
case "-":
oper = new OperationSub();
break;
case "*":
oper = new OperationMul();
break;
case "/":
oper = new OperationDiv();
break;
default:
break;
}
return oper;
}
}
客户端调用
public class Main {
public static void main(String[] args){
Operation oper = OperationFactory.createOperation("*");
oper.setNumberA(5);
oper.setNumberB(3);
double result = oper.getResult();
System.out.println(result);
}
}