大话设计模式------简单工厂模式

Posted 2022-12-08 zsmcwp

工厂方法模式：工厂方法模式定义一个用于创建对象的接口，让子类决定实例化哪一个类。工厂方法使一个类的实例化延迟到其子类。

一、简单工厂模式：

实例化对象的时候不再使用 new Object()形式，可以根据用户的选择条件来实例化相关的类。对于客户端来说，去除了具体的类的依赖。只需要给出具体实例的描述给工厂，工厂就会自动返回具体的实例对象。

 

 

import lombok.Data;

@Data
public abstract class Operation 

    private double numberA = 0;
    private double numberB = 0;

    public abstract double getResult() throws Exception;

public class OperationAdd extends Operation
    @Override
    public double getResult() 
        return getNumberA() + getNumberB();
    

public class OperationSub extends Operation 
    @Override
    public double getResult() 
        return getNumberA() - getNumberB();
    

public class OperationMul extends Operation 
    @Override
    public double getResult() 
        return getNumberA() * getNumberB();
    

public class OperationDiv extends Operation  
    @Override
    public double getResult() throws Exception 
        if(getNumberB() == 0)
            throw new Exception("除数不能为0");
        
        return getNumberA() / getNumberB();
    

public class OperationFactory 

    public static Operation createOperation(String operate)
        Operation operation = null;
        switch (operate)
            case "+" :
                operation = new OperationAdd();
                break;
            case "-" :
                operation = new OperationSub();
                break;
            case "*" :
                operation = new OperationMul();
                break;
            case "/" :
                operation = new OperationDiv();
                break;
        
        return operation;
    

public class TestOperation 

    public static void main(String[] args) 
        Operation operation = OperationFactory.createOperation("+");
        try 
            operation.setNumberA(10);
            operation.setNumberB(20);
            System.out.println(operation.getResult());
         catch (Exception e) 
            e.printStackTrace();