在 XML 配置中引用 JavaConfig 时出现 NoSuchBeanDefinitionException

Question

我是 Spring 的初学者，正在尝试学习使用 XML 和 Java Config 类配置 Spring bean 的不同方法。在下面的演示程序中，我在 Java Config 类中配置了 EmployeeService 和 EmployeeDAO bean，在 XML 文件中配置了 Employee bean。然后我试图在 XML 配置中引用 JavaConfig，并在 Main Class 中使用这个 XML 配置文件来获取 Employee Service bean。我在执行以下程序时收到 NoSuchBeanDefinitionException。有人可以帮我理解这里出了什么问题。

DAOConfig.java 包 com.demo.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import com.demo.dao.EmployeeDAO;

@Configuration
public class DAOConfig {

    @Bean
    public EmployeeDAO getEmployeeDAO(){
        return new EmployeeDAO();
    }

}

ServiceConfig.java 包 com.demo.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import com.demo.dao.EmployeeDAO;
import com.demo.service.EmployeeService;

@Configuration
public class ServiceConfig {

    @Bean(name="myEmployeeService")
    public EmployeeService getEmployeeService(EmployeeDAO empDAO){
        EmployeeService empService = new EmployeeService();
        empService.setEmpDAO(empDAO);
        return empService;
    }
}

MainConfig.java

包 com.demo.config;

import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;

@Configuration
@Import({ DAOConfig.class, ServiceConfig.class })
public class MainConfig {

}

EmployeeService.java：

package com.demo.service;

import com.demo.dao.EmployeeDAO;

public class EmployeeService {

    private EmployeeDAO empDAO;

    public void setEmpDAO(EmployeeDAO empDAO) {
        this.empDAO = empDAO;
    }

    public void insertEmployee() {
        System.out.println("insertEmployee called..");
        empDAO.insertEmployeeDetails();
    }

    public void updateEmployee() {
        System.out.println("updateEmployee called..");
        empDAO.updateEmployeeDetails();
    }

    public void deleteEmployee() {
        System.out.println("deleteEmployee called..");
        empDAO.deleteEmployeeDetails();
    }

}

EmployeeDAO.java

    package com.demo.dao;

public class EmployeeDAO {

    public void insertEmployeeDetails(){
        System.out.println("insertEmployeeDetails called..");
    }

    public void updateEmployeeDetails(){
        System.out.println("updateEmployeeDetails called..");
    }

    public void deleteEmployeeDetails(){
        System.out.println("deleteEmployeeDetails called..");
    }

}

Employee.java：

package com.demo.dto;

public class Employee {

    private String name;
    private String id;
    private String salary;

    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    public String getSalary() {
        return salary;
    }
    public void setSalary(String salary) {
        this.salary = salary;
    }

    @Override
    public String toString() {
        return "Employee [name=" + name + ", id=" + id + ", salary=" + salary + "]";
    }
}

mixAppContext.xml：

<?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"
    xsi:schemaLocation="http://www.springframework.org/schema/beans  
               http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">

    <bean class="com.demo.config.MainConfig" />

    <bean id="employeeObj" class="com.demo.dto.Employee">
        <property name="name" value="ABC"></property>
        <property name="id" value="123"></property>
        <property name="salary" value="10000"></property>
    </bean>

</beans>   

JavaConfigInXmlMixDemo.java：

package com.demo.main;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.demo.dto.Employee;
import com.demo.service.EmployeeService;

public class JavaConfigInXmlMixDemo {

    public static void main(String args[]){
        //ApplicationContext context = new AnnotationConfigApplicationContext(MainConfig.class);
        ApplicationContext context = new ClassPathXmlApplicationContext("mixAppContext.xml");

        EmployeeService service =     (EmployeeService) context.getBean("myEmployeeService");
        Employee employee = (Employee) context.getBean("employeeObj");

        service.insertEmployee();
        service.updateEmployee();
        service.deleteEmployee();

        System.out.println(employee);
    }

}

我遇到了以下异常：

例外：

INFO: Loading XML bean definitions from class path resource [mixAppContext.xml]
Exception in thread "main" org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'myEmployeeService' is defined
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanDefinition(DefaultListableBeanFactory.java:701)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getMergedLocalBeanDefinition(AbstractBeanFactory.java:1180)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:284)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1076)
    at com.demo.main.JavaConfigInXmlMixDemo.main(JavaConfigInXmlMixDemo.java:15)

Answer 1

就像描述的here 一样，您需要在您的xml 中包含<context:annotation-config />。如果没有这个标签，spring 将忽略所有注释并创建配置 bean 的实例，因为它是一个简单的 bean。