@The difference between resource and @autowired annotation, why recommend @resource?

2 Both can be used to assemble bean, When the interface has only a single implementation class , The two annotations have the same decoration effect , They can replace each other , Not affecting use .
1.
@Autowired Assembly by type by default （ This note is industry spring Of ）, By default, dependency objects must exist , If you want to allow null value , You can set its required The attribute is false, Such as ：@Autowired(required=false) , If we want to use name assembly, we can combine @Qualifier Use annotations

@Resource（ This note belongs to J2EE Of ）, By default, assemble by name , The name can be given by name Property to specify , If not specified name attribute , When comments are written on fields , By default, the field name is used to search the installation name , If the note is written in setter Method, the property name is used for assembly by default . When no match can be found for the name bean Assembly according to type . But here's the thing , If name Property once specified , Just assemble by name .

When an interface has 2 Implementation cases ：
give an example ：

An interface ：

public interface UserDao {
    public void insert();
}

Realization 1：

@Repository("userJdbcDao")
public class UserJdbcDao implements UserDao{
    @Override
    public void insert() {
        System.out.println(" I am a -jdbc-Dao- Implement the insert operation ");
    }
}

Realization 2：

@Repository("userJndiDao")
public class UserJndiDao implements UserDao{
    @Override
    public void insert() {
        System.out.println(" I am a -jndi-Dao- Implement the insert operation ");
    }
}

service class ：

@Service("userService")
public class UserService {

    @Autowired
    @Qualifier("userJdbcDao")
    private UserDao userDao=null;
    
    public void createUser(){
        userDao.insert();
    }
}

1. here ide Will detect what you injected Dao It's not the only one , May adopt @Qualifier Use with annotations , Specify which... You want to inject dao
2. It can also be used on classes that implement interfaces ：
@Primary In case of conflict, which implementation class should be used first

Recommended ：@Resource：

Implementation class ：@Repository(“userJdbcDao”) and service Of @Resource(name=“userJdbcDao”) Be consistent
UserJdbcDao Different implementation class names do not affect

@Repository("userJdbcDao") // life beanId
public class UserJdbcDao implements UserDao{
    @Override
    public void insert() {
        System.out.println(" I am a -jdbc-Dao- Implement the insert operation ");
    }
}

@Service("userService")
public class UserService {
    @Resource(name="userJdbcDao")
    private UserDao userDao=null;

    public void createUser(){
        userDao.insert();
    }
}

@SpringBootTest
class TestApplicationTests {

    @Resource(name="userService")
    private UserService userService;

    @Test
    public void testcreateUser(){
        userService.createUser();
    }
}

Code ：
Test code source address

The article comes from It Lao Qi 001