问如何使用bean定义对象在运行时生成/创建新的spring bean？

EN

abstract class BeanDefinition {

  abstract public void preprocess();

}

// now we have 1st user specific bean :
class UserSpecifiedBeanDefinition extends BeanDefinition{

  @override
  public void preprocess() {
     // do something
  }

}


// we could have more user-specific beans that extend BeanDefinition
....




// Following generator class is used to generate beans

public class BeanGenerator {

  private BeanDefinition beanDefinition;
  public BeanGenerator(BeanDefinition beanDefinition) {
    this.beanDefinition = beanDefinition;
  }
  public generate() {
    BeanDefinition newBean = // create new bean based on beanDefinition? how can I make this work??
    newBean.preprocess();
    return newBean;
  }
}

// In spring.xml, I would like to use them like:
<bean id="generator1" class="com.xxx.xxx.BeanGenerator">
    <constructor-arg name="beanDefinition" ref="userSpecifiedBeanDefinition"/>
</bean>