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Spring的注解@Qualifier小结

时间:2019-04-25 11:48:00      阅读:169      评论:0      收藏:0      [点我收藏+]

标签:问题   tor   request   nts   bsp   div   expected   https   cep   

近期在捯饬spring的注解,现将遇到的问题记录下来,以供遇到同样问题的童鞋解决~

  先说明下场景,代码如下:

有如下接口:

public interface EmployeeService {
    public EmployeeDto getEmployeeById(Long id);
}

  

同时有下述两个实现类 EmployeeServiceImpl和EmployeeServiceImpl1:

 

@Service("service")
public class EmployeeServiceImpl implements EmployeeService {
    public EmployeeDto getEmployeeById(Long id) {
        return new EmployeeDto();
    }
}

@Service("service1")
public class EmployeeServiceImpl1 implements EmployeeService {
    public EmployeeDto getEmployeeById(Long id) {
        return new EmployeeDto();
    }
}

  调用代码如下:

@Controller
@RequestMapping("/emplayee.do")
public class EmployeeInfoControl {
    
    @Autowired
    EmployeeService employeeService;
     
    @RequestMapping(params = "method=showEmplayeeInfo")
    public void showEmplayeeInfo(HttpServletRequest request, HttpServletResponse response, EmployeeDto dto) {
        #略
    }
}

  在启动tomcat时报如下错误:

org.springframework.beans.factory.BeanCreationException:
Error creating bean with name ‘employeeInfoControl‘:
Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException:
Could not autowire field: com.test.service.EmployeeService com.test.controller.EmployeeInfoControl.employeeService;
nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException:
No unique bean of type [com.test.service.EmployeeService] is defined:
expected single matching bean but found 2: [service1, service2]

  

  其实报错信息已经说得很明确了,在autoware时,由于有两个类实现了EmployeeService接口,所以Spring不知道应该绑定哪个实现类,所以抛出了如上错误。

这个时候就要用到@Qualifier注解了,qualifier的意思是合格者,通过这个标示,表明了哪个实现类才是我们所需要的,我们修改调用代码,添加@Qualifier注解,需要注意的是@Qualifier的参数名称必须为我们之前定义@Service注解的名称之一!

@Controller
@RequestMapping("/emplayee.do")
public class EmployeeInfoControl {
    
    @Autowired
    @Qualifier("service")
    EmployeeService employeeService;
    
    @RequestMapping(params = "method=showEmplayeeInfo")
    public void showEmplayeeInfo(HttpServletRequest request, HttpServletResponse response, EmployeeDto dto) {
        #略
    }
}

  

文章转载至:https://www.cnblogs.com/smileLuckBoy/p/5801678.html

 

Spring的注解@Qualifier小结

标签:问题   tor   request   nts   bsp   div   expected   https   cep   

原文地址:https://www.cnblogs.com/nhdlb/p/10767385.html

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