簡(jiǎn)單的工廠模式

QiShare 發(fā)布于2019-08-16 17:35 / 2405人閱讀

摘要：簡(jiǎn)單工廠模式什么是簡(jiǎn)單工廠模式簡(jiǎn)單的工廠模式到底要實(shí)例誰(shuí)，將來(lái)會(huì)不會(huì)增加實(shí)例化的對(duì)象，都應(yīng)該考慮用一個(gè)多帶帶的類來(lái)做這個(gè)創(chuàng)造實(shí)例的過(guò)程，這就是工廠。

                                  ## 簡(jiǎn)單工廠模式 ##

什么是簡(jiǎn)單工廠模式

**簡(jiǎn)單的工廠模式**：到底要實(shí)例誰(shuí)，將來(lái)會(huì)不會(huì)增加實(shí)例化的對(duì)象，都應(yīng)該考慮用一個(gè)多帶帶的類來(lái)做這個(gè)創(chuàng)造實(shí)例的過(guò)程，這就是工廠。

步驟一

public class OperationObject {
    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;
    }
    public double getResult(){
        double result = 0;
        return result;
    }
}

步驟二

//加法
public class OperationAdd extends OperationObject {
    public double getResult(){
        double result = 0;
        result = get_numberA()+get_numberB();
        return result;
    }
}
//加法
public class OperationDiv extends OperationObject{
    public double getResult() {
        double result = 0;
        if (get_numberB() == 0){
            try {
                throw new Exception("除數(shù)不能為零");
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        result = get_numberA() / get_numberB();
        return result;
    }
}
//乘法
public class OperationMul extends OperationObject {
    public double getResult(){
        double result = 0;
        result = get_numberA() * get_numberB();
        return result;
    }
}
//除法
public class OperationSub extends OperationObject {
    public double getResult(){
        double result = 0;
        result = get_numberA() - get_numberB();
        return result;
    }
}

步驟三

//簡(jiǎn)單的工廠模式：到底要實(shí)例誰(shuí)，將來(lái)會(huì)不會(huì)增加實(shí)例化的對(duì)象，都應(yīng)該考慮用一個(gè)多帶帶的類來(lái)做這個(gè)創(chuàng)造實(shí)例的過(guò)程，這就是工廠。
//一句話就是一個(gè)工廠里面裝著一堆需要實(shí)例的對(duì)象
public class OperationFactory {
    public static OperationObject createOperation(String operation){
        //負(fù)責(zé)生產(chǎn)加減乘除
        OperationObject operationObject = null;
        switch (operation){
            case "+":
                operationObject = new OperationAdd();
                break;
            case "-":
                operationObject = new OperationSub();
                break;
            case "*":
                operationObject = new OperationMul();
                break;
            case "/":
                operationObject = new OperationDiv();
                break;
        }
        return operationObject;
    }
}

步驟四

public class factoryDesign {
    public static void main(String[] args) {
        //實(shí)例所需要的計(jì)算類型
        OperationObject operationObject = OperationFactory.createOperation("-");
        operationObject.set_numberA(2);
        operationObject.set_numberB(4);
        double result = operationObject.getResult();
        System.out.println(result);
    }
}

簡(jiǎn)單工廠的問(wèn)題就在于swich case（或者if else)。每當(dāng)新增一種產(chǎn)品時(shí)，你都需要去維護(hù)工廠中的判斷語(yǔ)句，造成該工廠類不斷增長(zhǎng)，各種判斷擠在一起，給擴(kuò)展和維護(hù)帶來(lái)麻煩。產(chǎn)品和工廠沒(méi)有實(shí)現(xiàn)完全解耦，綁定在一起。
以上內(nèi)容為個(gè)人學(xué)習(xí)大話設(shè)計(jì)模式后筆記，不喜勿噴。