2021-6-3 anglehua
I am going through some blogs on SpringSource and in one of the blogs, author is using @Inject and I suppose he can also use @Autowired.
Here is the piece of code:
@Inject private CustomerOrderService customerOrderService;
I am not sure about the difference between @Inject and @Autowired and would appreciate it if someone explained their difference and which one to use under what situation?
Assuming here you're referring to the javax.inject.Inject annotation. @Inject is part of the Java CDI (Contexts and Dependency Injection) standard introduced in Java EE 6 (JSR-299), read more. Spring has chosen to support using the @Inject annotation synonymously with their own @Autowired annotation.
So, to answer your question, @Autowired is Spring's own annotation. @Inject is part of a Java technology called CDI that defines a standard for dependency injection similar to Spring. In a Spring application, the two annotations works the same way as Spring has decided to support some JSR-299 annotations in addition to their own.
Here is a blog post that compares @Resource, @Inject, and @Autowired, and appears to do a pretty comprehensive job.
From the link:
With the exception of test 2 & 7 the configuration and outcomes were identical. When I looked under the hood I determined that the ‘@Autowired’ and ‘@Inject’ annotation behave identically. Both of these annotations use the ‘AutowiredAnnotationBeanPostProcessor’ to inject dependencies. ‘@Autowired’ and ‘@Inject’ can be used interchangeable to inject Spring beans. However the ‘@Resource’ annotation uses the ‘CommonAnnotationBeanPostProcessor’ to inject dependencies. Even though they use different post processor classes they all behave nearly identically. Below is a summary of their execution paths.
Tests 2 and 7 that the author references are 'injection by field name' and 'an attempt at resolving a bean using a bad qualifier', respectively.
The Conclusion should give you all the information you need.