文字理解

簡單工廠模式又 叫靜態(tài)工廠方法模式（Static FactoryMethod Pattern）,是通過專門定義一個類來負(fù)責(zé)創(chuàng)建其他類的實例，被創(chuàng)建的實例通常都具有共同的父類。

簡單描述

簡單工廠將對象的創(chuàng)建過程進行了封裝，用戶不知道到底創(chuàng)建了什么對象，只需要調(diào)用工廠類，工廠類按照自己的邏輯進行創(chuàng)建對象。

代碼理解

現(xiàn)在有一道面試題：

使用java實現(xiàn)一個計算機控制臺程序，要求輸入數(shù)的運算，得到結(jié)果。

public abstract class Operation {

    public abstract float getResult(float firstNumber, float secondNumber);

}

//把符號都當(dāng)做對象處理，實現(xiàn)此接口
public class AddOperation extends Operation {
    @Override
    public float getResult(float firstNumber, float secondNumber) {
        return firstNumber+secondNumber;
    }

}
public class SubOperation extends Operation {
    @Override
    public float getResult(float firstNumber, float secondNumber) {
        return firstNumber-secondNumber;
    }
}
public class MulOperation extends Operation {
    @Override
    public float getResult(float firstNumber, float secondNumber) {
        return firstNumber*secondNumber;
    }
}
public class DivOperation extends Operation {
    @Override
    public float getResult(float firstNumber, float secondNumber) {
        return firstNumber/secondNumber;
    }
}

//接下來需要解決的就是對象的創(chuàng)建問題了，既如何根據(jù)不同的情況創(chuàng)建不同的對象：我們正好可以通過簡單工廠模式實現(xiàn)
public class OperationFactory {

    public static Operation getOperation(String quotaFlag){
        Operation o = null;
        switch (quotaFlag){
            case "+" :  o = new AddOperation();
            case "-" :  o = new SubOperation();
            case "*" :  o = new MulOperation();
            case "/" :  o = new DivOperation();
            default:break;
        }
        return o;
    }
}
//調(diào)用：
public class Computer {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.println("請輸入第一個數(shù)字：");
        float firstNum  = in.nextFloat();
        System.out.println("請輸入第二個數(shù)字：");
        float secondNum  = in.nextFloat();
        System.out.println("請輸入運算符號：");
        String countQuato = in.next();
        System.out.println(count(firstNum,secondNum,countQuato));
    }
    private static float count(float firstNum,float secondNum , String countQuota){
    //通過工廠類獲取對象
        Operation operation = OperationFactory.getOperation(countQuota);
        return operation.getResult(firstNum,secondNum);
    }
}