1.类继承关系

2.接口定义

public interface InstantiationStrategy {

    //默认构造方法
    Object instantiate(RootBeanDefinition beanDefinition, String beanName, BeanFactory owner) throws BeansException;

    //指定构造方法
    Object instantiate(RootBeanDefinition beanDefinition, String beanName, BeanFactory owner, Constructor<?> ctor,
            Object[] args) throws BeansException;

    //指定工厂方法
    Object instantiate(RootBeanDefinition beanDefinition, String beanName, BeanFactory owner, Object factoryBean,
            Method factoryMethod, Object[] args) throws BeansException;

}

3.代码示例

public class InstantiationStrategyTest {

    @Test
    public void test1() {

        DefaultListableBeanFactory factory = new DefaultListableBeanFactory();
        RootBeanDefinition beanDefinition=new RootBeanDefinition(TestBean.class);
        factory.registerBeanDefinition("testBean", beanDefinition);
        InstantiationStrategy strategy= (InstantiationStrategy) FieldUtils.getProtectedFieldValue("instantiationStrategy",factory);
        TestBean bean= (TestBean) strategy.instantiate(beanDefinition,"testBean",factory);
    }

    @Test
    public void test2() throws NoSuchMethodException {

        DefaultListableBeanFactory factory = new DefaultListableBeanFactory();
        RootBeanDefinition beanDefinition=new RootBeanDefinition(TestBean.class);
        factory.registerBeanDefinition("testBean", beanDefinition);

        Constructor<TestBean> constructor=TestBean.class.getDeclaredConstructor(String.class);
        InstantiationStrategy strategy= (InstantiationStrategy) FieldUtils.getProtectedFieldValue("instantiationStrategy",factory);
        TestBean bean= (TestBean) strategy.instantiate(beanDefinition,"testBean",factory,constructor,"test1");
    }

    @Test
    public void test3() throws NoSuchMethodException {

        DefaultListableBeanFactory factory = new DefaultListableBeanFactory();
        RootBeanDefinition beanDefinition=new RootBeanDefinition(TestBean.class);
        factory.registerBeanDefinition("testBean", beanDefinition);

        TestBeanFactory testBeanFactory=new TestBeanFactory();

        InstantiationStrategy strategy= (InstantiationStrategy) FieldUtils.getProtectedFieldValue("instantiationStrategy",factory);
        TestBean bean= (TestBean) strategy.instantiate(beanDefinition,"testBean",factory,testBeanFactory,TestBeanFactory.class.getMethod("createBean"));
    }
}