Spring IoC依赖查找

Spring IoC依赖查找类型如下：

1. 根据Bean名称（id）查找，在Spring的一个上下文中，名称（id）必须唯一

   • 实时查找：马上查找，马上所得

   • 延迟查找

     注：spring 应用可以有多个上下文

       BeanFactory beanFactory = new ClassPathXmlApplicationContext("classpath:/dependency/lookupDemo.xml");
       //实时查找
       lookUpRealTime(beanFactory);
       //延迟查找
       lookUpLazyTime(beanFactory);
   
        /**
        * spring ioc实时查找
        */
       public static void lookUpRealTime(BeanFactory beanFactory) {
           LookupUser lookupUser = (LookupUser) beanFactory.getBean("lookupUser");
           System.out.println(lookupUser.toString());
       }
       
       /**
        *org.springframework.beans.factory.ObjectFactory
        * ObjectFactory,没有生成新的bean, FactoryBean则会生成新的bean
        * ObjectFactoryCreatingFactoryBean ** 可以看下实现，一个很欢乐的设计模式
        *
        */
       public static void lookUpLazyTime(BeanFactory beanFactory) {
   
           ObjectFactory objectFactory = (ObjectFactory) beanFactory.getBean("objectFactory");
           LookupUser user = objectFactory.getObject();
           System.out.println("lazy:"+user);
   
       }
   

2. 根据Bean类型查找

   • 单个Bean对象
   • 集合Bean对象

       BeanFactory beanFactory = new ClassPathXmlApplicationContext("classpath:/dependency/lookupDemo.xml");
       //查找单个对象
       lookUpByType(beanFactory);
       //查找集合对象
       lookupByCollectionType(beanFactory);
       
       
       public static void lookUpByType(BeanFactory beanFactory) {
        LookupUser user = beanFactory.getBean(LookupUser.class);
        System.out.println(user.toString());
       }
   
        /**
        * 复合类型查找
        */
       private static void lookupByCollectionType(BeanFactory beanFactory) {
           if(beanFactory instanceof ListableBeanFactory){
               ListableBeanFactory listableBeanFactory = (ListableBeanFactory) beanFactory;
               //map，ke
               Map lookupUserMap = listableBeanFactory.getBeansOfType(LookupUser.class);
               System.out.println(lookupUserMap);
           }
       }
   

3. 根据Bean名称+类型查找

4. 根据Java注解查找

   • 单个Bean对象
   • 集合Bean对象

   //自定义注解
   @Target({ElementType.TYPE})
   @Retention(RetentionPolicy.RUNTIME)
   public @interface Super {
   }
   
    BeanFactory beanFactory = new ClassPathXmlApplicationContext("classpath:/dependency/lookupDemo.xml");
    //根据注解查找集合类型
    lookupByAnnotationCollection(beanFactory);
    
   private static void lookupByAnnotationCollection(BeanFactory beanFactory) {
       if(beanFactory instanceof ListableBeanFactory){
           ListableBeanFactory listableBeanFactory = (ListableBeanFactory) beanFactory;
           //map，key, 查找符合自定义注解的Bean
           Map lookupUserMap = listableBeanFactory.getBeansWithAnnotation(Super.class);
           System.out.println(lookupUserMap);
       }
   }