大话设计模式(自己手写java代码完成例子4)

大话设计模式

1.9紧耦合vs松耦合

1.10简单工厂模式

自己写的java代码

package btdp.one.night;

public abstract class Operation {

double numberA;

double numberB;

public abstract double result() throws Exception;

}

package btdp.one.night;

public class OperationAdd extends Operation {

@Override
public double result() {
    return numberA + numberB;
}
           

}

package btdp.one.night;

public class OperationSub extends Operation {

@Override
public double result() {
    return numberA - numberB;
}
           

}

package btdp.one.night;

public class OperationMul extends Operation {

@Override
public double result() {
    return numberA * numberB;
}
           

}

package btdp.one.night;

public class OperationDiv extends Operation {

@Override
public double result() throws Exception {
    if (numberB == 0) {
        throw new Exception("除数不能为0");
    }
    return numberA / numberB;
}
           

}

package btdp.one.night;

public class OperationFactory {

public static Operation createOperate(char 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;

}

}

package btdp.one.night;

public class Client {

public static void main(String[] args) throws Exception {

Operation oper;

oper = OperationFactory.createOperate(‘+’);

oper.numberA = 234;

oper.numberB = 123;

double result = oper.result();

System.out.println(result);

}

}