Spring@Autowired和@Qualifier[closed]

Question

是否使用@autowired自动检测？使用@qualifier时是否按名称进行依赖注入？我们如何使用这些注释进行setter和constructor注入？

Answer 1

您可以将@qualifier与@autowired一起使用。事实上，如果发现不明确的bean类型，spring会要求您显式地选择bean，在这种情况下，您应该提供限定符

例如，在以下情况下，有必要提供一个限定符

@Component
@Qualifier("staff") 
public Staff implements Person {}

@Component
@Qualifier("employee") 
public Manager implements Person {}


@Component
public Payroll {

    private Person person;

    @Autowired
    public Payroll(@Qualifier("employee") Person person){
          this.person = person;
    }

}

编辑：

@Component
@Qualifier("staff") 
public Staff implements Person {}

@Component
@Qualifier("employee") 
public Manager implements Person {}


@Component
@RequiredArgsConstructor
public Payroll {
   @Qualifier("employee") private final Person person;
}

# Copy the Qualifier annotation from the instance variables to the constructor
# see https://github.com/rzwitserloot/lombok/issues/745
lombok.copyableAnnotations += org.springframework.beans.factory.annotation.Qualifier

null

public Payroll {
   @Autowired @Qualifier("employee") private final Person person;
}

public Payroll {
   private final Person person;
   @Autowired
   @Qualifier("employee")
   public void setPerson(Person person) {
     this.person = person;
   } 
}

如果您使用的是构造函数注入，那么注释应该放在构造函数上，否则代码将无法工作。像下面这样使用-

public Payroll {

    private Person person;

    @Autowired
    public Payroll(@Qualifier("employee") Person person){
          this.person = person;
    }

}