The Spring IoC dependency lookup types are as follows:

  1. Lookup by Bean name (ID). In one Spring context, the name (ID) must be unique

    • Real-time search: Search now, get it now

    • Delay to find

      Note: Spring applications can have multiple contexts

    BeanFactory beanFactory = new ClassPathXmlApplicationContext("classpath:/dependency/lookupDemo.xml"); LookUpRealTime (beanFactory); // Delay lookUpLazyTime(beanFactory); Public static void lookUpRealTime(BeanFactory BeanFactory) {LookupUser LookupUser = (LookupUser) beanFactory.getBean("lookupUser"); System.out.println(lookupUser.toString()); * * *} / org. Springframework. Beans. Factory. The ObjectFactory * ObjectFactory, not generate new bean, ObjectFactoryCreatingFactoryBean FactoryBean will generate a new bean * * * may have a look, Public static void lookUpLazyTime(BeanFactory BeanFactory) {ObjectFactory<LookupUser> ObjectFactory = (ObjectFactory<LookupUser>) beanFactory.getBean("objectFactory"); LookupUser user = objectFactory.getObject(); System.out.println("lazy:"+user); }Copy the code

  2. Lookup by Bean type

    • Single Bean object
    • Collection Bean object
    BeanFactory beanFactory = new ClassPathXmlApplicationContext("classpath:/dependency/lookupDemo.xml"); // Look for a single object lookUpByType(beanFactory); LookupByCollectionType (beanFactory); public static void lookUpByType(BeanFactory beanFactory) { LookupUser user = beanFactory.getBean(LookupUser.class); System.out.println(user.toString()); } private static void lookupByCollectionType(BeanFactory BeanFactory) {if(BeanFactory instanceof) ListableBeanFactory){ ListableBeanFactory listableBeanFactory = (ListableBeanFactory) beanFactory; / / map, ke map < String, LookupUser > lookupUserMap = listableBeanFactory. GetBeansOfType (LookupUser. Class); System.out.println(lookupUserMap); }}Copy the code

  3. Lookup by Bean name + type

  4. Find according to Java annotations

    • Single Bean object
    • Collection Bean object
    @target ({elementtype.type}) @Retention(retentionPolicy.runtime) public @interface Super {} BeanFactory beanFactory = new ClassPathXmlApplicationContext("classpath:/dependency/lookupDemo.xml"); / / consult collection types according to the annotation lookupByAnnotationCollection (the beanFactory); private static void lookupByAnnotationCollection(BeanFactory beanFactory) { if(beanFactory instanceof ListableBeanFactory){ ListableBeanFactory listableBeanFactory = (ListableBeanFactory) beanFactory; / / map, key, discover the custom annotation of Bean map < String, Object > lookupUserMap = listableBeanFactory. GetBeansWithAnnotation (Super) class); System.out.println(lookupUserMap); }}Copy the code