Use @Qualifier annotated with @Primary
Spring ApplicationContext role in
BeanFactory and ApplicationContext difference
AnnotationConfigApplicationContext start Principle Analysis
Suppose two IUser implementation class and UserImpl2 UserImpl1
1. @Autowired + @Qualifier ( "UserImpl1") can specify which implementation class to use. Can also @Resource ( "UserImpl1")
2. @Primary who is designated to load, used in the implementation class. Specified.