Spring 3 Autowired BeanInitializationException

Question

@Autowired我遇到了一个很大的问题,那就是异常返回

bean的初始化失败; 嵌套异常是org.springframework.beans.factory.BeanInitializationException:bean'A'需要属性'serviceFactory'

以下是所有内容的简要说明(我使用的是Spring 3.2,并且我已将所有jar放在正确的位置WEB-INF/lib).

applicationContext.xml中

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:p="http://www.springframework.org/schema/p" 
        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-3.2.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-3.2.xsd">

<context:annotation-config />
<context:component-scan base-package="com.sc" />

<!-- Comment out - we are going to use @Component @Autowired - 2014-01-07
<bean id="A" class="com.sc.A">
  <property name="serviceFactory" ref="serviceFactoryBean" />
</bean> 
-->

<bean id="serviceFactoryBean" class="com.sc.ServiceFactory" autowire="byName" />

</beans>

com.sc.A类的内容

@Component
public class A
{

private Logger logger = Logger.getLogger(A.class);

// @Autowired -- 2014-01-07 comment out as not need it since annotation in setter below
// @Qualifier("serviceFactoryBean")
private ServiceFactory serviceFactory;

public A()
{ }

@Autowired // add 2014-01-07
@Required
public void setServiceFactory(ServiceFactory serviceFactory)
{
  this.serviceFactory = serviceFactory;
}

public boolean checkSomething() 
{
  if(this.serviceFactory == null)
   logger.error("serviceFactory is null. Autowired failed");

 // do something
}


} // end of class A

类com.sc.ServiceFactory的内容

// @Component -- comment out 2014-01-07
public class ServiceFactory
{
  // do whatever
}

然后我编译了这些类并在jetty中运行它,当jetty上升时,它总是抛出很长的例外

org.springframework.beans.factory.BeanCreationException:创建在URL中定义名称为"A"的bean时出错... bean的初始化失败; 嵌套异常是org.springframework.beans.factory.BeanInitializationException:bean'A'需要属性'serviceFactory'

我尝试了很多有和没有注释的组合无济于事.面对这个错误是非常令人沮丧的.

请帮忙

Answer 1

在你的问题中有一些错误(或者说是误解).

使用当前上下文,您将为每个A和声明两个bean定义ServiceFactory.一个隐含地来自@Component注释,<component-scan>另一个来自显式<bean>声明.选择其中一个或者您可能会发现自己处于Spring不知道使用哪个位置.

有了上述内容,Spring会A因为它的@Component注释而尝试生成一个bean,并@Required在setServiceFactory()方法上查看,但不知道如何处理它.@Required的贾瓦多克说

将方法(通常是JavaBean setter方法)标记为"required":即,必须将setter方法配置为使用值依赖注入.

但在你的情况下,事实并非如此.添加@Autowired到它.

@Required
@Autowired
public void setServiceFactory(ServiceFactory serviceFactory) {
    this.serviceFactory = serviceFactory;
}

现在Spring将知道如何处理该方法,即.注入一个ServiceFactory豆子.