Question

我在2个不同的项目中有2个班级，我在使用字段进行自动装配时遇到了一些困难。

在项目包中，我有这个Computation类：

package fr.aaa;

@Component
public class Computation {
    @Autowired
    @Qualifier("curveDAO")
    CurveAccess curveDAO;

    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("classpath*:applicationContext.xml");
    }
}

在项目数据库中，我有这个CurveAccess接口：

package com.bbb

public interface CurveAccess {
    // some methods
}

由CurveDAO类实现：

package com.bbb.impl

@Repository("curveDAO")
@Transactional("cvaTxManager")
public class CurveDAO implements CurveAccess {
    // some methods
}

我的pack项目中的applicationContext.xml文件：

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:tx="http://www.springframework.org/schema/tx" xmlns:util="http://www.springframework.org/schema/util"
xmlns:security="http://www.springframework.org/schema/security" xmlns:context="http://www.springframework.org/schema/context"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd
    http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.1.xsd      
    http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.1.xsd
    http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.1.xsd
    http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd
    http://www.springframework.org/schema/security http://www.springframework.org/schema/security/spring-security-3.0.3.xsd">  

<import resource="classpath:spring/persistence.xml"/>

<context:annotation-config />
<context:component-scan base-package="fr.aaa.*, com.bbb.*"/> 

<util:properties id="jdbcProps" location="jdbc.properties" />   

<bean id="propertyConfigurer"
    class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
    <property name="locations">
        <list>
         <value>classpath:configuration.properties</value>
         <value>classpath:jdbc.properties</value>
        </list>
    </property>
</bean>

运行时，我有这个例外：

Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'Computation': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.bbb.CurveAccess fr.aaa.Computation.curveDAO; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [com.bbb.CurveAccess] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true), @org.springframework.beans.factory.annotation.Qualifier(value=curveDAO)}

我该如何解决这个问题？

Answer 1

实际上，您的代码完全正常：

@SpringBootApplication
public class So21481801Application implements CommandLineRunner {

    public interface CurveAccess {
        String hello();
    }

    @Repository("curveDAO")
    public class CurveDAO implements CurveAccess {
        @Override
        public String hello() {
            return "Hello";
        }
    }

    @Repository("curveDAOWorld")
    public class CurveDAOWorld implements CurveAccess {
        @Override
        public String hello() {
            return "World";
        }
    }

    @Autowired
    @Qualifier("curveDAO")
    CurveAccess curveDAO;

    @Autowired
    @Qualifier("curveDAOWorld")
    CurveAccess curveDAOWorld;

    @Override
    public void run(String... args) {
        System.out.println(curveDAO.hello());
        System.out.println(curveDAOWorld.hello());
    }

    public static void main(String[] args) {
        ConfigurableApplicationContext context = SpringApplication.run(So21481801Application.class, args);
        context.close();
    }

}

对于如何在XML和Java注释上使用component-scan配置，可能存在一些问题。混合它们不是一个好主意。

Answer 2

您需要一个实现CurveAccess接口

的类

@Component
public class CurveAccessImpl implements CurveAccess {
    //methods
}

同时从Qualifier bean中的curveDao中删除Computation，因为没有ID为curveDao的bean。

@Autowired
CurveAccess curveDAO;

BeanCreationException：注入自动连接的依赖项失败

2 个答案: