设计模式--简单工厂应用 java

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要实现java面向对象，那么我们来写个简单的工厂来实现java的封装、继承、复用的例子，还有，我们顺便实现函数式的简单工厂。

一、简单工厂（非函数式）

1、首先我们将通用的属性合方法放在一个普通类里边

/**
 * Created by LK on 2016/5/8.
 */
public class Operation {
    private double numberA = 0;
    private double numberB = 0;

    public double getNumberA() {
        return numberA;
    }

    public void setNumberA(double numberA) {
        this.numberA = numberA;
    }

    public double getNumberB() {
        return numberB;
    }

    public void setNumberB(double numberB) {
        this.numberB = numberB;
    }

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

2、假如说，我们现在要实现算法的加减乘除，那么我们分别创建对应的类继承上面的普通类

加法：

/**
 * Created by LK on 2016/5/8.
 */
public class OperationsAdd extends Operation {
    public double getResult(){
        double result = 0;
        result = getNumberA() + getNumberB();
        return result;
    }
}

/**
 * Created by LK on 2016/5/8.
 */
public class OperationSub extends Operation{
    public double getResult(){
        double result = 0;
        result = getNumberA() - getNumberB();
        return result;
    }
}

/**
 * Created by LK on 2016/5/8.
 */
public class OperationMul extends Operation {
    public double getResult(){
        double result = 0;
        result = getNumberA() * getNumberB();
        return result;
    }
}

/**
 * Created by LK on 2016/5/8.
 */
public class OperationDiv extends Operation {
    public double getResult(){
        double result = 0;
        if(getNumberB() == 0){
            System.out.println("除数不能为0！");
        }
        result = getNumberA() / getNumberB();
        return result;
    }
}

/**
 * Created by LK on 2016/5/8.
 */
public class OperationFactory {
    public static Operation createOperate(String operate){
        Operation oper = null;
        switch (operate){
            case "+":
                oper = new OperationsAdd();
                break;
            case "-":
                oper = new OperationSub();
                break;
            case "*":
                oper = new OperationMul();
                break;
            case "/":
                oper = new OperationDiv();
                break;
        }
        return oper;
    }
}

/**
 * Created by LK on 2016/5/8.
 */
public class FactoryClient {
    public static void main(String[] args) {
        /**
         * 简单工厂模式，方法一
         */
        Operation operation = OperationFactory.createOperate("/");
        operation.setNumberA(2);
        operation.setNumberB(1);
        double result = operation.getResult();
        System.out.println(result);
        /**
         * 简单工厂模式，方法二
         */
        /*String oper = "/";
        IOperationFunction operationFunction = OperationFunction.getOperationFunctionStrategy(oper);
        double result1 = operationFunction.createOperation(2,1,oper);
        System.out.println(result1);*/
    }
}

为了简化实现类的产生，我们可以考虑用函数式的方法去实现

1、创建一个函数式的接口

/**
 * Created by LK on 2016/5/8.
 */
@FunctionalInterface  public interface IOperationFunction {
    public double createOperation(double numberA,double numberB,String oper);
}

/**
 * Created by LK on 2016/5/8.
 */
public class OperationFunction {
    private static Map<String,IOperationFunction> operationFunctionMap = new ConcurrentHashMap<>();

    static{
        /**
         * 加法运算
         */
        operationFunctionMap.put("+",(numberA,numberB,oper) ->{
            double result = numberA + numberB;
            return result;
        });

        /**
         * 减法运算
         */
        operationFunctionMap.put("-",(numberA,numberB,oper) ->{
            double result = numberA - numberB;
            return result;
        });

        /**
         * 乘法运算
         */
        operationFunctionMap.put("*",(numberA,numberB,oper) -> {
            double result = numberA * numberB;
            return result;
        });

        /**
         * 除法运算
         */
        operationFunctionMap.put("/",(numberA,numberB,oper) -> {
            double result = numberA / numberB;
            return result;
        });
    }

    public static IOperationFunction getOperationFunctionStrategy(String oper){
        return operationFunctionMap.get(oper);
    }
}

3、现在，也只是欠厂长的召唤了

/**
 * Created by LK on 2016/5/8.
 */
public class FactoryClient {
    public static void main(String[] args) {
        /**
         * 简单工厂模式，方法一
         */
      /*  Operation operation = OperationFactory.createOperate("/");
        operation.setNumberA(2);
        operation.setNumberB(1);
        double result = operation.getResult();
        System.out.println(result);*/
        /**
         * 简单工厂模式，方法二
         */
        String oper = "/";
        IOperationFunction operationFunction = OperationFunction.getOperationFunctionStrategy(oper);
        double result1 = operationFunction.createOperation(2,1,oper);
        System.out.println(result1);
    }
}

设计模式--简单工厂应用 java

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原文地址：http://blog.csdn.net/lk10207160511/article/details/51344949