简单工厂模式

１．简单工厂模式结构图

２．示例代码：

public interface Product {
    void doSomething();
}

public class ProductA implements Product{
    @Override
    public void doSomething() {
        System.out.println("这是产品Ａ！");
    }
}

public class ProductB implements Product{
    @Override
    public void doSomething() {
        System.out.println("这是产品Ｂ！");
    }
}


public class SimpleFactory {

    private int a = 1;
    private int b = 2;

    public Product makeProduct(int type) {
        Product product = null;
        if (a == type) {
            product = new ProductA();
        } else if (b == type) {
            product = new ProductB();
        }
        return product;
    }

    public Product makeProduct(String className) {
        Product product = null;
        if (null != className && className.trim() != ""){
            try {
                product = (Product)Class.forName(className).getDeclaredConstructor().newInstance();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return product;
    }

    public Product makeProduct(Class<? extends Product> clazz) {
        Product product = null;
        if (null != clazz){
            try {
                product = clazz.getDeclaredConstructor().newInstance();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return product;
    }
}

3. 总结：

   优点：结构简单，调用方便；工厂和产品的职责区分明确．

   缺点：工厂类单一，若产品增多，则代码臃肿，违背高聚合原则．