Spring的注解@Qualifier小结
本文内容纲要:
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:
publicinterfaceEmployeeService{
publicEmployeeDtogetEmployeeById(Longid);
}
同时有下述两个实现类EmployeeServiceImpl和EmployeeServiceImpl1:
@Service("service")
publicclassEmployeeServiceImplimplementsEmployeeService{
publicEmployeeDtogetEmployeeById(Longid){
returnnewEmployeeDto();
}
}
@Service("service1")
publicclassEmployeeServiceImpl1implementsEmployeeService{
publicEmployeeDtogetEmployeeById(Longid){
returnnewEmployeeDto();
}
}
调用代码如下:
@Controller
@RequestMapping("/emplayee.do")
publicclassEmployeeInfoControl{
@Autowired
EmployeeServiceemployeeService;
@RequestMapping(params="method=showEmplayeeInfo")
publicvoidshowEmplayeeInfo(HttpServletRequestrequest,HttpServletResponseresponse,EmployeeDtodto){
#略
}
}
在启动tomcat时报如下错误:
org.springframework.beans.factory.BeanCreationException:Errorcreatingbeanwithname'employeeInfoControl':Injectionofautowireddependenciesfailed;nestedexceptionisorg.springframework.beans.factory.BeanCreationException:Couldnotautowirefield:com.test.service.EmployeeServicecom.test.controller.EmployeeInfoControl.employeeService;nestedexceptionisorg.springframework.beans.factory.NoSuchBeanDefinitionException:Nouniquebeanoftype[com.test.service.EmployeeService]isdefined:expectedsinglematchingbeanbutfound2:[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")
publicclassEmployeeInfoControl{
@Autowired
@Qualifier("service")
EmployeeServiceemployeeService;
@RequestMapping(params="method=showEmplayeeInfo")
publicvoidshowEmplayeeInfo(HttpServletRequestrequest,HttpServletResponseresponse,EmployeeDtodto){
#略
}
}
问题解决!
本文内容总结:
原文链接:https://www.cnblogs.com/smileLuckBoy/p/5801678.html