工厂方法模式

工厂方法模式的实质是“定义一个创建对象的接口，但让实现这个接口的类来决定实例化哪个类。工厂方法让类的实例化推迟到子类中进行。

UML类图

代码实现

IFactory

package com.lei.designpatterns.factorymethod;

import com.lei.designpatterns.simplefactory.Operation;

public interface IFactory {
    Operation createOperation();
}

AddFactory

package com.lei.designpatterns.factorymethod;

import com.lei.designpatterns.simplefactory.Operation;
import com.lei.designpatterns.simplefactory.OperationAdd;

public class AddFactory implements IFactory {
    @Override
    public Operation createOperation() {
        return new OperationAdd();
    }
}

SubFactory

package com.lei.designpatterns.factorymethod;

import com.lei.designpatterns.simplefactory.Operation;
import com.lei.designpatterns.simplefactory.OperationSub;

public class SubFactory implements IFactory {
    @Override
    public Operation createOperation() {
        return new OperationSub();
    }
}

MulFactory

package com.lei.designpatterns.factorymethod;

import com.lei.designpatterns.simplefactory.Operation;
import com.lei.designpatterns.simplefactory.OperationMul;

public class MulFactory implements IFactory {
    @Override
    public Operation createOperation() {
        return new OperationMul();
    }
}

DivFactory

package com.lei.designpatterns.factorymethod;

import com.lei.designpatterns.simplefactory.Operation;
import com.lei.designpatterns.simplefactory.OperationDiv;

public class DivFactory implements IFactory {
    @Override
    public Operation createOperation() {
        return new OperationDiv();
    }
}

附录

依赖简单工厂模式