Question

我是春天的新人。但尝试基本的东西。根据理论我应该工作，它不起作用。我有2个不同id的相同bean。我应该能够@Autowired使用唯一身份@Qualifier("PersonBean2")。但它给出了错误。我不知道哪里出了什么问题。请通知我？谢谢！

config springBeans.xml在哪里： -

 <beans xmlns="http://www.springframework.org/schema/beans"
  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-2.5.xsd">

<bean    

 class="org.springframework.beans.factory.annotation.
  AutowiredAnnotationBeanPostProcessor"/>


  <bean id="customer" class="com.mkyong.common.Customer" >
    <property name="action" value="buy" />
    <property name="type" value="1" />
</bean>

<bean id="PersonBean1" class="com.mkyong.common.Person">
    <property name="name" value="mkyong1" />
    <property name="address" value="address 1" />
    <property name="age" value="28" />
</bean>

  <bean id="PersonBean2" class="com.mkyong.common.Person">
    <property name="name" value="mkyong2" />
    <property name="address" value="address 2" />
    <property name="age" value="28" />
    </bean>

   </beans>

Customer.java： -

public class Customer {

@Autowired
@Qualifier("PersonBean2")
private Person person;
private int type;
private String action;
}

Person.java： -

public class Person {
private String name;
private String address;
private int age;
}

删除所有setter和getter。

测试app.java： -

public class App {
  public static void main(String[] args) {
    ApplicationContext context = new ClassPathXmlApplicationContext(
            "SpringBeans.xml");

    Customer cust = (Customer) context.getBean("customer");
    System.out.println(cust);
  }
}

错误： -


Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'customer': Autowiring of fields failed; 
    nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.mkyong.common.Person com.mkyong.common.Customer.person; 
    nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No unique bean of type [com.mkyong.common.Person] is defined: expected single matching bean but found 2: [PersonBean1, PersonBean2]

Answer 1

它应该工作！似乎@Qualifier注释没有按预期工作。

仔细检查是否正在从包org.springframework.beans.factory.annotation中导入@Qualifier注释

Answer 2

<bean class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor" />

您添加了AutowiredAnnotationBeanPostProcessor，顾名思义，它只处理@Autowired注释。而不是直接使用处理器添加<context:annotation-config />，这会添加额外的处理器，同时考虑@Qualifier。

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

    <context:annotation-config />

另一个提示更喜欢无版本架构spring-beans.xsd而不是版本化架构spring-beans-2.5.xsd。

为什么Spring基本的@Autowired不起作用？

2 个答案: