@Autowired-找不到至少1个依赖项类型的合格Bean [英] @Autowired - No qualifying bean of type found for dependency at least 1 bean

问题描述

目前，我在控制器和服务层之间的Autowire配置中遇到问题.

Currently I'm facing an issue in Autowire configuration between controller and the service layer.

我无法追踪我的错误.

简单日志信息

    SEVERE:   Exception while loading the app
    SEVERE:   Undeployment failed for context /OTT
    SEVERE:   Exception while loading the app : java.lang.IllegalStateException: ContainerBase.addChild: start: org.apache.catalina.LifecycleException: org.apache.catalina.LifecycleException: org.springframework.beans.factory.NoSuchBeanDefinitionException: 
No qualifying bean of type [com.ott.service.EmployeeService] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {}

下面，我还给出了控制器和服务层代码，以及dispatcher-servlet.xml

Below I have also given the Controller and Service Layer code and also the dispatcher-servlet.xml

控制器

package com.ott.controller;

import com.ott.service.EmployeeService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

    /**
     *
     * @author SPAR
     */
    @Controller
    public class AdminController {

        private EmployeeService employeeService;

        @RequestMapping("/employee")
        public String employee(){
            this.employeeService.fetchAll();
            return "employee";
        }

        @Autowired(required = true)
        @Qualifier(value="employeeService")
        public void setEmployeeService(EmployeeService empService) {
            this.employeeService = empService;
        }

    }

服务界面

package com.ott.service;

import com.ott.hibernate.Employee;
import java.util.List;

/**
 *
 * @author SPAR
 */
public interface EmployeeService {

     List<Employee> fetchAll();


}

服务界面编号

package com.ott.service;

import com.ott.dao.EmployeeDAO;
import com.ott.hibernate.Employee;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

/**
 *
 * @author SPAR
 */
@Service
public class EmployeeServiceImpl implements EmployeeService{

    private EmployeeDAO employeeDAO;

    @Override
    @Transactional(readOnly = true)
    public List<Employee> fetchAll() {

        List<Employee> employees = employeeDAO.fetchAll();
        for (Employee employee : employees) {

            System.out.println("Name : "+employee.getFirst_Name() +" "+ employee.getLast_Name());

            System.out.println("Email Id : "+employee.getEmail_Id());
        }

        return employees;
    }

    @Autowired(required = true)
    @Qualifier(value="employeeDAO")
    public void setEmployeeDAO(EmployeeDAO empDAO) {
        this.employeeDAO = empDAO;
    }
}

Dispatcher-servlet.xml

 <?xml version='1.0' encoding='UTF-8' ?>
    <!-- was: <?xml version="1.0" encoding="UTF-8"?> -->
    <beans xmlns="http://www.springframework.org/schema/beans"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xmlns:p="http://www.springframework.org/schema/p"
           xmlns:aop="http://www.springframework.org/schema/aop"
           xmlns:tx="http://www.springframework.org/schema/tx"
           xmlns:context="http://www.springframework.org/schema/context"
           xmlns:mvc="http://www.springframework.org/schema/mvc"       
           xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
           http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
           http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
           http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd
           http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd">

        <context:component-scan base-package="com.ott.controller"/>
        <context:component-scan base-package="com.ott.hibernate"/>
        <context:component-scan base-package="com.ott.service"/>
        <context:component-scan base-package="com.ott.dao"/>

        <bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping"/>
        <bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter"/>

        <mvc:resources mapping="/resources/**" location="/resources/" />

         <bean id="tilesConfigurer" class="org.springframework.web.servlet.view.tiles3.TilesConfigurer">
            <property name="definitions">
                <list>
                    <value>/WEB-INF/tiles-def/general-layout.xml</value>
                </list>
            </property>
        </bean>

        <bean id="viewResolverTiles" class="org.springframework.web.servlet.view.UrlBasedViewResolver">
            <property name="viewClass" value="org.springframework.web.servlet.view.tiles3.TilesView"/>
        </bean> 

        <mvc:annotation-driven />

        <bean
          class="org.springframework.web.servlet.view.InternalResourceViewResolver">
          <property name="prefix">
            <value>/WEB-INF/pages/</value>
          </property>
          <property name="suffix">
            <value>.jsp</value>
          </property>
        </bean>
    </beans>

推荐答案

您不必提供姓名和限定词.如果设置一个名称，那么就是在上下文中注册该bean的名称.如果您没有提供服务的名称，它将基于BeanNameGenerator注册为无大写的不合格类名.因此，在您的情况下，实现将注册为employeeServiceImpl.因此，如果您尝试使用该名称自动接线，则应该直接解析.

You don't have to necessarily provide name and Qualifier. If you set a name, that's the name with which the bean is registered in the context. If you don't provide a name for your service it will be registered as uncapitalized non-qualified class name based on BeanNameGenerator. So in your case the Implementation will be registered as employeeServiceImpl. So if you try to autowire with that name, it should resolve directly.

private EmployeeService employeeServiceImpl;

@RequestMapping("/employee")
public String employee() {
    this.employeeService.fetchAll();
    return "employee";
}

@Autowired(required = true)
public void setEmployeeService(EmployeeService employeeServiceImpl) {
    this.employeeServiceImpl = employeeServiceImpl;
}

@Qualifier用于以下情况:如果存在多个相同类型的bean，并且您希望出于各种目的自动装配不同的实现bean.

@Qualifier is used in case if there are more than one bean exists of same type and you want to autowire different implementation beans for various purposes.

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