设计模式--创建型模式--简单工厂模式（Simple Factory）---"术业有专攻"

简单工厂模式（案例）：
1.公用接口Salary

package com.design.simplefactory;

public interface Salary {
    void computerSalery();

}

2.实现接口的类：BeiJingSalary

package com.design.simplefactory;

public class BeiJingSalary implements Salary {

    @Override
    public void computerSalery() {
        System.out.println("computer BeiJing Salary");
    }

}

3.实现接口的类：HeiBeiSalary

package com.design.simplefactory;

public class HeiBeiSalary implements Salary {

    @Override
    public void computerSalery() {
        System.out.println("computer HeiBei salary");
    }

}

4.负责对象的创建（简单工厂也叫静态工厂）：SimpleFactory

package com.design.simplefactory;

public class SimpleFactory {
    public static Salary createSalary(String className){
            try {
                Class cls = Class.forName(className);
                Salary salary = (Salary) cls.newInstance();
                return salary;
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
            } catch (InstantiationException e) {
                e.printStackTrace();
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            }
        
        return null;
    }
}

5.客户端调用：Client

package com.design.simplefactory;

public class Client {
    public static void main(String[] args){
        Salary salary = SimpleFactory.createSalary("com.design.simplefactory.HeiBeiSalary");
        salary.computerSalery();
        salary = SimpleFactory.createSalary("com.design.simplefactory.BeiJingSalary");
        salary.computerSalery();
    }

}

优点：客户端不再负责对象的创建，而把这个责任丢给了具体的工厂类SimpleFactory,客户端只负责对对象的调用，从而明白了各个类的职责。
缺点：后期不容易维护（考虑到具体产品的不断增多）
适用于：要创建的具体对象比较少或简单的情况下。