基于泛型访问DI容器

短命女 2022-08-06 13:22 98阅读 0赞

为显示地访问宿主在DI容器(包括BeanFactory和ApplicationContext)中的受管Bean,开发者需要在调用getBean()方法后,完成对象的造型操作,因此编译期很难知道造型正确与否.Spring 2.x引入的GenericBeanFactoryAccessor辅助类能避免造型操作,它借用到了JDK5.0中的泛型特性.这一辅助类对DI容器进行了包裹,并提供了大量的辅助方法.

以下是一个示例:

package test; import java.util.Map; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.springframework.beans.factory.ListableBeanFactory; import org.springframework.beans.factory.generic.GenericBeanFactoryAccessor; import org.springframework.beans.factory.xml.XmlBeanFactory; import org.springframework.core.io.ClassPathResource; import org.springframework.core.io.Resource; /\*\* \* 使用GenericBeanFactoryAccessor \* \* @author zxs \*/ public class GenericBeanFactoryAccessorDemo \{ protected static final Log log = LogFactory .getLog(GenericBeanFactoryAccessorDemo.class); public static void main(String\[\] args) \{ Resource res = new ClassPathResource("generic.xml"); ListableBeanFactory bf = new XmlBeanFactory(res); //同样适用于ApplicationContext GenericBeanFactoryAccessor gbf = new GenericBeanFactoryAccessor(bf); //不用进行造型 ITestBean1 tb1 = gbf.getBean("tb1"); log.info(tb1); //要求返回TestBean1类型，且id是tb2的受管Bean ITestBean1 tb2 = gbf.getBean("tb2", TestBean1.class); log.info(tb2); //返回ITestBean1类型的受管Bean集合。期间，允许返回原型Bean Map<String, ITestBean1> mapTestBean1 = gbf.getBeansOfType( ITestBean1.class, true, false); log.info(mapTestBean1); //返回那些在类一级使用了@ForYou注释的受管Bean集合 Map<String, Object> map = gbf.getBeansWithAnnotation(ForYou.class); log.info(map); \} \}