大话设计模式之简单工厂模式

package simple_factory;

public abstract class Operation {
private double numberA = 0;
private double numberB = 0;
public double getNumberA() {
return numberA;
}
public double getNumberB() {
return numberB;
}
public void setNumberA(double numberA) {
this.numberA = numberA;
}
public void setNumberB(double numberB) {
this.numberB = numberB;
}
public abstract double GetResult() throws Exception;

public static void main(String[] args) throws Exception {
// TODO Auto-generated method stub
Operation oper;
oper = OperationFactory.createOperation("+");
oper.setNumberA(1);
oper.setNumberB(2);
double result = oper.GetResult();
System.out.println(result);
}
}

class OperationAdd extends Operation {
@Override
public double GetResult() {
double result = 0;
result = this.getNumberA() + this.getNumberB();
return result;
}
}

class OperationSub extends Operation {
@Override
public double GetResult() {
double result = 0;
result = this.getNumberA() - this.getNumberB();
return result;
}
}

class OperationMul extends Operation {
@Override
public double GetResult() {
double result = 0;
result = this.getNumberA() * this.getNumberB();
return result;
}
}

class OperationDiv extends Operation {
@Override
public double GetResult() throws Exception {
double result = 0;
if (this.getNumberB() == 0)
throw new Exception("除数不能为0");
result = this.getNumberA() / this.getNumberB();
return result;
}
}

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;
}
return oper;
}
}