I don’t see any difference between two ways, @Qualifier is always used with @Autowired.
@Autowired
@Qualifier("alpha")
VS
@Resource(name="alpha")
Anyone could let me know the difference? Thanks!
See Question&Answers more detail:osI don’t see any difference between two ways, @Qualifier is always used with @Autowired.
@Autowired
@Qualifier("alpha")
VS
@Resource(name="alpha")
Anyone could let me know the difference? Thanks!
See Question&Answers more detail:os@Autowired
can be used alone . If it is used alone , it will be wired by type . So problems arises if more than one bean of the same type are declared in the container as @Autowired
does not know which beans to use to inject. As a result , use @Qualifier
together with @Autowired
to clarify which beans to be actually wired by specifying the bean name (wired by name)
@Resource
is wired by name too . So if @Autowired
is used together with @Qualifier
, it is the same as the @Resource
.
The difference are that @Autowired
and @Qualifier
are the spring annotation while @Resource
is the standard java annotation (from JSR-250) . Besides , @Resource
only supports for fields and setter injection while @Autowired
supports fields , setter ,constructors and multi-argument methods injection.
It is suggested to use @Resource
for fields and setter injection. Stick with @Qualifier
and @Autowired
for constructor or a multi-argument method injection.
See this:
If you intend to express annotation-driven injection by name, do not primarily use @Autowired - even if is technically capable of referring to a bean name through @Qualifier values. Instead, prefer the JSR-250 @Resource annotation which is semantically defined to identify a specific target component by its unique name, with the declared type being irrelevant for the matching process.