学习目标：

雷锋依然在人间——工厂方法模式

学习内容：

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1、搭建 Java 开发环境
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1、简单工厂的实现
1.1 以计算机为例，结构图
在这里插入图片描述
1.2 工厂类这样写

package org.xunfang.test;

public class Operation {
    private double _numberA=0;
    private double _numberB=0;

    public double get_numberA() {
        return _numberA;
    }

    public void set_numberA(double _numberA) {
        this._numberA = _numberA;
    }

    public double get_numberB() {
        return _numberB;
    }

    public void set_numberB(double _numberB) {
        this._numberB = _numberB;
    }

    //静态方法不可以重写
    /*public static double getResult(){
        double result = 0;
        return result;
    }*/
    public double getResult() throws Exception {
        double result = 0;
        return result;
    }
}

package org.xunfang.test;

public class OperationAdd extends Operation {
    @Override
    public double getResult() {
        double result = 0;
        result = this.get_numberA()+this.get_numberB();
        return result;
    }
}

package org.xunfang.test;

public class OperationSub extends Operation {
    @Override
    public double getResult() {
        double result = 0;
        result = this.get_numberA() - this.get_numberB();
        return result;
    }
}

package org.xunfang.test;

public class OperationMul extends Operation {
    @Override
    public double getResult() {
        double result = 0;
        result = this.get_numberA()* this.get_numberB();
        return result;
    }
}

package org.xunfang.test;

public class OperationDiv extends Operation {

    @Override
    public double getResult() throws Exception {
        double result = 0;
        if (this.get_numberB() == 0) {
            throw new Exception("除数不能为0");
        }
        result = this.get_numberA() / this.get_numberB();
        return result;
    }
}

package org.xunfang.test;

public class OperationFactory {
    public static Operation createOperate(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;
    }
}

package org.xunfang.test;

public class Send {
    public static void main(String[] args) throws Exception {
        Operation operation;
        operation = OperationFactory.createOperate("+");
        operation.set_numberA(1);
        operation.set_numberB(2);
        /*operation.get_numberA();
        operation.get_numberB();*/
        double result = operation.getResult();
    }
}